The Distribution of Life on Earth 2Nd Pages © Jones & Bartlett Learning, LLC

Life has co-evolved with the Earth’s atmosphere, © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC hydrosphere, and lithosphere to create an NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION integrated “living” planet. Living things help cycle the elements and sustain an oxygen atmosphere while the Earth provides a © Jones & Bartlett Learning, LLC © Jones &habitable Bartlett envir Learning,onment LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALEfor life. OR DISTRIBUTION

The© Jones Distribution & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC ofNOT Life FOR SALE ORon DISTRIBUTION Earth NOT FOR SALE OR DISTRIBUTION4

© Jones & Bartletthis is Learning,a special time LLC in Earth’s long history. The© Jones continents & Bartlett are widely Learning, separated. LLC Chapter Objectives NOT FOR SALEThe OR global DISTRIBUTION climate is relatively cool comparedNOT with FOR what SALE it has OR been DISTRIBUTION for most After reading this chapter, T of Earth’s history, and life has had time to adapt to its physical environment you should be able to without interruption from a cataclysmic event. The Earth holds an unusually high explain or describe the number of species. following: In this chapter, we examine how species originated and discuss estimates of the • How life may have originated number of species on© Earth Jones today. & Bartlett We see thatLearning, life arose LLC rather early in Earth’s history© Jones & Bartlett Learning, LLC and has diversifiedNOT into FORmany SALEspecies OR through DISTRIBUTION the process of evolution via naturalNOT FOR • SALE How life OR evolved DISTRIBUTION and diversified by natural selection. Indeed, there are now so many species that biologists have scarcely begun selection the task of classifying and describing them all. Sadly, as species continue to disappear • How to measure as a result of direct and indirect human activities, some species clearly will be gone biodiversity before© Jonesthey are & found Bartlett and Learning,described. NoLLC one really knows how© fast Jones species & areBartlett dis- Learning,• The seven LLC major land appearing,NOT FOR but scientists SALE OR put DISTRIBUTION the numbers between 1,000 and 10,000NOT timesFOR whatSALE the OR DISTRIBUTIONbiomes of the world normal or “natural” rate would be if people were not affecting the planet. A lack of • The two major aquatic professional biologists who are trained to study insects and other groups that are so biomes of the world abundant hinders the efforts to find and describe them. The information biologists can provide is very important in debates over how fast species are going extinct and what © Jones &percentage Bartlett ofLearning, Earth’s species LLC are disappearing. © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 105 2nd pAGES © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION.

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTIONWe also see how species are distributedNOT on FOR OtherSALE regions, OR DISTRIBUTION such as grasslands, with rich Earth. Species are neither randomly nor evenly soils for crops, are affected because they are distributed because their distribution is closely resource rich and we can rapidly exploit them. related to the physical conditions to which they are adapted. Rainfall and temperature are especially crucial© Jones in determining & Bartlett whichLearning, suites ofLLC 4.1 Evolution ©of Jones the Biosphere & Bartlett Learning, LLC species canNOT survive FOR in SALE any given OR region.DISTRIBUTION Some Primitive fossilized bacteriaNOT FOR are atSALE least 3.5OR bil DISTRIBUTION- species are narrowly adapted to very limited lion years old. This indicates that life arose not conditions in one area, whereas other species, long after the molten Earth first became cool such as the wolf, were once found across many enough to support life. This very early appear- © Jonescontinents. & Bartlett Human Learning, impacts, LLC such as on spe- ance© of Jones life implies & Bartlett that natural Learning, processes LLC read- NOT FORcies distributions, SALE OR DISTRIBUTIONare not randomly or evenly ily produceNOT FOR life underSALE appropriate OR DISTRIBUTION conditions. distributed. Some regions, such as deserts, are Beginning in the early 1950s with the work of more sensitive than others to our disturbance. Stanley Miller and Harold Urey, scientists have shown that the complex molecules possessed by all living things are readily produced under © Jones & Bartlett Learning, LLC © Jones &laboratory Bartlett conditionsLearning, that LLC duplicate early en- NOT FOR SALE OR DISTRIBUTIONWater NOT FOR SALE OR DISTRIBUTIONFigure 4-1 vapor vironments on Earth. As shows, the early atmosphere is thought to have been com- Sparks posed of ammonia (NH ), methane (CH ), CH4 3 4 NH Gases 3 water vapor (H2O), and other gases. When © Jones & Bartlett Learning,H 2LLCO these are subjected ©to Joneselectricity, & Bartlettwhich simu Learning,- LLC H2 NOT FOR SALE OR DISTRIBUTIONlates lightning and sunlight,NOT FOR chemical SALE reactions OR DISTRIBUTION occur that produce amino acids. Amino acids Vacuum Electrodes are complex molecules that are the building blocks of proteins. Proteins make up enzymes Electrical discharge and many other components of life, such as © Jones & Bartlett Learning, LLC muscles,© Jones hair, and& Bartlett skin. Learning, LLC NOT FOR SALE OR DISTRIBUTION NOTOf course, FOR SALEprotein ORmolecules DISTRIBUTION alone are not living things. Organisms are composed of

Cooling molecules that are organized in very complex jacket ways. The basic organizational unit of life is the cell. Remarkably, in the late 1950s, Sidney © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Fox found that heated amino acids can form NOT FOR SALE OR DISTRIBUTION NOT FOR cell-likeSALE ORstructures DISTRIBUTION sometimes called proto- cells. These structures are not true cells but have many cell-like properties, such as being semipermeable to certain materials. Boiling water © Jones & Bartlett Learning, LLC Producing amino© Jonesacids and & Bartlettprotocells Learning, in LLC NOT FOR SALE OR DISTRIBUTIONthe laboratory is farNOT from FOR creating SALE life ORin the DISTRIBUTION laboratory. Even the simplest bacteria are con- Trap for siderably more complex than these protein withdrawing and protocellular building blocks. Neverthe- sample less, the readiness with which these first steps © Jones & Bartlett Learning, LLC toward© Jones life occur, & Bartlett combined Learning, with the LLC fossil NOT FOR SALE OR DISTRIBUTION record,NOT support FOR SALEthe idea OR that DISTRIBUTION life readily arose through natural processes.

Evolution Through Natural Selection FIGURE 4-1 This is a simplified schematic of the experimental apparatus that Miller and Urey © Jones &used Bartlett to show that or Learning,ganic molecules can LLCbe produced from the chemical components ©of th Jonese &After Bartlett life originated, Learning, it beganLLC to diversify into NOT FOREarth’s SALE early atm ORosphere. DISTRIBUTION NOT FOR differentSALE OR kinds DISTRIBUTION of organisms through biologi- 106 Chapter 4 The Distribution of Life on Earth 2nd pAGES © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION.

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FORcal SALE evolution. OR DISTRIBUTIONAs Charles Darwin documented NOTClass FOR Mammalia SALE OR DISTRIBUTION in 1859, biological evolution occurs because Order Primates of natural selection of individual variation: Family Hominidae Genus Homo 1. Nearly all populations exhibit variation Species H. sapiens* among individuals.© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC 2. Individuals with advantageous traits will NOT FOR SALE OR DISTRIBUTIONDiversification of the Biosphere NOT FOR SALE OR DISTRIBUTION tend to have more fertile offspring. 3. Advantageous traits will therefore be- Where does individual variation come from? come widespread in populations. This question is crucial because without the initial variation in the population, natural Variation© Jones in neck & Bartlettlength in Learning,giraffes is an LLC ex- selection would© have Jones nothing & Bartlett to act on. Learning, This LLC ample.NOT We FOR know SALE from ORfossils DISTRIBUTION that early gi- question troubledNOT Darwin FOR SALE because OR he DISTRIBUTION was raffes had relatively short necks. However, not aware of the work of Gregor Mendel, a few individuals had genes that produced who is credited with discovering the laws of slightly longer necks. In some localities, these inherited variation in 1865. Indeed, initially giraffes had a feeding advantage because they © Jones & Bartlett Learning, LLC ©Mendel’s Jones work & Bartlett was overlooked, Learning, and LLC scientists could browse on leaves in taller trees. Conse- rediscovered it only in the early 1900s. Men- NOT FORquently, SALE inOR populations DISTRIBUTION living where tall trees NOTdel discovered FOR SALE that genesOR DISTRIBUTION, which are the basic were common, longer-necked giraffes tended units of heredity, pass on traits. According to to have more offspring and passed on genes the Human Genome Project, humans have an for longer neck growth so that longer necks estimated 30,000 to 40,000 genes that deter- became more common.© Jones & Bartlett Learning,mine LLC our traits. Variation in a ©population, Jones & orBartlett Learning, LLC If this process NOToccurs FOR with SALE many ORtraits DISTRIBUTION gene pool, occurs because individualsNOT FOR possess SALE OR DISTRIBUTION over a long period of time, the population will different sets of genes that produce different eventually become very different from other traits. How do different sets of genes arise? populations and will create a new species. Fig- Reproduction is one way. Genes are shuffled ure 4-2 illustrates how isolation of populations when sperm and egg cells are fused, causing © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC promotes speciation. The different populations offspring from the same parents to have differ- are exposedNOT FOR to different SALE ORenvironments, DISTRIBUTION which ent genes. A secondNOT cause FOR of geneticSALE variationOR DISTRIBUTION is favor different traits, causing the populations mutation, which is a spontaneous change in a to diverge through time. When do two differ- gene. Genes are composed of DNA molecules, ent populations become two different species? and mutations occur when DNA molecules © Jones &Biologists Bartlett generally Learning, define LLC a species as a group ©are Jones altered, & such Bartlett as during Learning, DNA replication. LLC of individuals that can interbreed to produce NOT FOR SALE OR DISTRIBUTION NOTMutation FOR is SALEthe ultimate OR DISTRIBUTION source of all genetic fertile offspring (this definition applies only to variation. sexual organisms; the issue of defining non- sexual species is a matter of debate in biologi- Patterns of Diversification cal circles). Therefore, a new species is formed Evolution through natural selection has when members of a ©diverging Jones population& Bartlett can Learning, produced LLC an increasingly diverse© Jones biosphere, & Bartlett Learning, LLC no longer successfullyNOT mate FOR with SALE populations OR DISTRIBUTION with the total number of speciesNOT becoming FOR SALE OR DISTRIBUTION of the ancestral species. Closely related species, greater through time. Initially, evolution was which have often diverged relatively recently, relatively slow. The right side of Figure 4-3 are grouped together within the same genus. summarizes the evolution of life on Earth. For about 2 billion years after the first ap- Similar© Jones genera & are Bartlett then Learning,grouped together LLC © Jones & Bartlett Learning, LLC within the same family. This method of classi- pearance of fossils, relatively few species of NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION fying species according to hierarchically nested simple single-celled organisms, such as vari- categories is a form of taxonomy. Applying ous bacteria and Cyanobacteria (formerly this system to humans, we have the following: *A species name must always be associated with a generic © Jones & BartlettKingdom Learning, Animalia LLC ©name Jones or abbreviation & Bartlett (in this case Learning, H. for Homo LLC). Humans are the species Homo sapiens; it is incorrect to call humans NOT FOR SALEPhylum OR ChordataDISTRIBUTION NOTsimply sapiens. FOR SALE OR DISTRIBUTION 4.1 Evolution of the Biosphere 107 2nd pAGES © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION.

Central population© Jones &Reduction Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FORof habitat SALE area OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Peripheral isolates (a)

(d) Barrier Barrier © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION (b)

Peripheral population not isolated© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Out-migration Peripheral isolates

© Jones(c) & Bartlett Learning, LLC (e) © Jones & Bartlett Learning, LLC FIGURE 4-2 (a) Reduction of habitat may leave small isolated populations, called peripheral isolates. (b) Barriers may form to isolate small populations. NOT(c) FOR Out-migration SALE to an isolatedOR DISTRIBUTIONarea may form small separated populations. In all cases (a–c),NOT the small FOR populati onsSALE can evolve OR into nDISTRIBUTIONew species. Isolated by thousands of miles of ocean, the Hawaiian honeycreeper has evolved into many forms, including species with short (d) and long (e) beaks. © Jack Jeffrey Photography.

known as blue-green algae), appear in the Figure 4-3, this explosion (which occurred © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC fossil record. A major change occurred about during the Cambrian Period of Earth history) NOT FOR SALE OR1.5 DISTRIBUTION billion years ago when more complexNOT FOR correspondsSALE OR DISTRIBUTIONto the time when modern oxy- cells, called eukaryotes, evolved. These cells gen levels were attained in the atmosphere. had a true nucleus, chromosomes, and spe- This permitted the evolution of more com- cialized cellular organelles such as mitochon- plex animals, which have a greater metabolic dria. Apparently,© Jones such & Bartlett complex Learning, cells were LLCa need for oxygen. © Jones & Bartlett Learning, LLC primary NOTimpetus FOR of SALEincreasing OR ratesDISTRIBUTION of evo- After the explosionNOT ofFOR life, SALE living ORthings DISTRIBUTION lution. Multicellular organisms, including diversified into new environments. As shown sponge-like and jellyfish-like creatures, ap- in Figure 4-3, life colonized the land (litho- peared in the oceans by at least 1 billion years sphere) and the air (atmosphere) during the ago. These probably evolved from colonies Paleozoic Era, which began with the explo- © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC of single-celled eukaryotes, such as protozoa, sion of life and ended with a global mass ex- NOT FORthat SALEbecame OR progressively DISTRIBUTION more specialized tinction.NOT TheFOR Mesozoic SALE OREra, DISTRIBUTION sometimes called and integrated. About 570 million years ago, the age of dinosaurs, was the second major the fossil record shows a rapid diversification, era, and it also ended with a mass extinc- sometimes called the explosion of life or the tion. The third and last era is the Cenozoic © Jones & Bartlett CambrianLearning, explosion LLC , when most of the ©major Jones &Era, Bartlett sometimes Learning, called theLLC age of mammals. NOT FOR SALE ORgroups DISTRIBUTION of animals first appear. As shownNOT in FOR AlthoughSALE OR catastrophes, DISTRIBUTION especially from aster- 108 Chapter 4 The Distribution of Life on Earth 2nd pAGES © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION.

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTIONEARTH’S EVOLUTION NOT FORLIFE’S SALE EVOLUTION OR DISTRIBUTION Era Age Lithosphere Hydrosphere Atmosphere Hydrosphere Lithosphere Atmosphere 0 Sea level “Ice ages” Low Global Cool temperature Flying CENOZOIC mammals Swimming Humans Flowering © Jones & Bartlett Learning, LLC mammals © Jones & Bartlett Learning, LLC Continents seed plants Advanced Mass NOT FOR SALE ORHigh DISTRIBUTION NOT FORinsects SALE ORBirds DISTRIBUTION separating Mammals extinction 65 mya Warm Swimming reptiles Reptiles Continents MESOZOIC Primitive separating Flying birds Mass © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning,reptiles LLC Low Cool Seed plants extinctionNOT FOR245 SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION mya Pangaea Primitive insects Warm Continents PALEOZOIC assembling Amphibians High Fishes © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning,Seedless LLC Invertebrates Algae plants NOT FORAbundant SALE OR570 DISTRIBUTION NOT FOR SALE OR DISTRIBUTION fossils mya Larger, slower Modern plates Multicellular life oxygen Sexual reproduction 1500 levels mya Complex cells Small, rapid PRECAMBRIAN plates© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC 3500 Plate tectonics Modern volume Origin of life mya NOT FORand SALE composition OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Crust forms Ocean origin 4600 Earth origin mya FIGURE 4-3 The left side of this diagram summarizes the changes in the Earth’s continents, oceans, and atmosphere, whereas the right side summarizes the evolution of life on Earth. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

oid and comet impacts and global climate is hierarchical. For example, genes occur in change, have temporarily caused species num- cells. Cells occur in organisms, and organ- bers to decrease through mass extinctions at isms occur in ecosystems (a review of the bio- © Jones &very Bartlett rare intervals, Learning, the overall LLC trend through- ©sphere Jones provides & Bartlett more information).Learning, LLC At what NOT FORout SALE these OR eras DISTRIBUTION is toward increasing numbers NOTlevel doFOR we SALEmeasure OR the DISTRIBUTION diversity of life in of species. Life has adapted to new environ- an area? The number of genes? Organisms? ments and found new ways of doing things Ecosystems? All can be used. through mutation and natural selection. We now live in a biosphere© Jones that is one& Bartlett of the most Learning, Measuring LLC Biodiversity © Jones & Bartlett Learning, LLC diverse in life’s long NOThistory. FOR SALE OR DISTRIBUTIONAlthough one can measure biodiversityNOT FOR bySALE OR DISTRIBUTION counting the variety of genes or ecosystems in an area, the most common method is to 4.2 What Is Biodiversity? count species. Species diversity is usually Biological diversity, or biodiversity, has many measured as species richness, which is the © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC definitions, but they all involve the variety of number of species that occur in an area. livingNOT things FOR in a SALE given area. OR DISTRIBUTIONFor instance, the Using species richnessNOT FOR is largely SALE a OR matter DISTRIBUTION of U.S. Office of Technology Assessment defines convenience: it is easier to tabulate the num- biodiversity as “the variety and variability ber of species in an area than to count genes among living organisms and the ecological (the genetic diversity) or ecosystems. Fortu- © Jones &complexes Bartlett in Learning, which they LLC occur.” One reason ©nately, Jones species & Bartlett diversity Learning, is generally LLC a good NOT FORfor SALE the lack OR of DISTRIBUTION a precise definition is that life NOTindicator FOR of SALEgenetic OR diversity DISTRIBUTION and ecosystem 4.2 What Is Biodiversity? 109 2nd pAGES © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION.

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE ORdiversity DISTRIBUTION as well. Nevertheless, even speciesNOT FOR found.SALE AOR recent DISTRIBUTION study reported more than richness omits important information about 4,000 bacteria species in a single gram of biodiversity, such as the abundance of each Norwegian soil. Most of these species were species. Species evenness is the distribution of previously unknown. individuals among species in a community. Another problem is that most biologists Biodiversity© Jones can & beBartlett measured Learning, at all geo LLC- have been concentrated© Jones in North & BartlettAmerica andLearning, LLC graphic NOTscales, FOR from SALE local OR to DISTRIBUTIONregional to Europe, but the tropicsNOT have FOR the SALE most species. OR DISTRIBUTION global. Figure 4-4a illustrates low diversity at Similarly, most biologists study life on land, both the local and regional scales. Regions but the oceans cover 70–75% of the Earth with low diversity often have fewer species and contain unknown numbers of species. © Jonesat the & Bartlettlocal level Learning, as well. As LLC Figure 4-4b illus- For ©instance, Jones after & Bartlett a December Learning, 2004 tsunami LLC NOT FORtrates, SALE regions OR with DISTRIBUTION high diversity tend to be thatNOT hit Southeast FOR SALE Asia, ORmany DISTRIBUTION rarely seen spe- composed of local biological communities cies were found washed up on the shores. It with high diversity. For instance, tropical is likely that taxonomists have considerably rain forests and tropical coral reefs tend to underestimated the number of species existing have very high species richness at both the in the tropics and the oceans. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC local and regional level compared with areas How Estimates Are Made NOT FOR SALE ORof DISTRIBUTION similar size in temperate zones. NOT FOR SALE OR DISTRIBUTION Describing all species on Earth could take cen- Global Biodiversity: How Many Species? turies, so biologists have devised a number of ways to develop immediate biodiversity esti- No one knows how many species live on mates of species numbers from limited infor- Earth. Taxonomists© Jones &, theBartlett biologists Learning, who clas LLC- mation. The following© Jones are just & three Bartlett examples Learning, LLC sify and NOTdescribe FOR organisms, SALE OR have DISTRIBUTION described of the many methodsNOT of estimatingFOR SALE global OR diDISTRIBUTION- approximately 1.8 to 2.0 million species. Of versity from small samples: these, 56% are insects, and 14% are plants; vertebrates such as birds, mammals, and fishes 1. Rain forest insect samples. Terry Erwin are just 3%. Only about 15% of described of the Smithsonian Institution has be- © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC species occur in the oceans. come well known for his studies of the NOT FORHowever, SALE OR these DISTRIBUTION 2 million species are a NOTvery FORdiverse SALE tropical OR insect DISTRIBUTION communities. highly biased sample and may not reflect Because most species are insects and most the true species richness of the biosphere. insects are tropical, these studies are im- For one thing, vertebrates are much more portant for global estimates (Figure 4-5). © Jones & Bartlett widelyLearning, studied LLC and, therefore much ©better Jones & BartlettErwin Learning,used insecticides LLC to kill and collect all of the insects in the canopy (upper NOT FOR SALE ORknown DISTRIBUTION than nonvertebrates: only one orNOT two FOR SALE OR DISTRIBUTION new species of birds are described each year, branches) of a tropical tree. In Panama, whereas hundreds of new invertebrates are for example, 1,200 beetle species were found in the canopy of a single tree. Be- Regional Regional cause about 40% of all insects are beetles, © Jones & Bartlett Learning, LLC we can estimate© Jonesthat perhaps & Bartlett 3,000 Learning,in- LLC NOT FORC SALE OR DISTRIBUTIONF sect species occurNOT there; FOR however,SALE OR only DISTRIBUTION A A G about two-thirds of the species occur in B C the canopy (the rest occur on roots, bark, A E and other places). The total number of B insects on this one tree is thus estimated © Jones & BartlettLocal Learning, LLC Local © Jones & Bartlett Learning, LLC at 4,500 species! Because many of these NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION A A A B insects occur only on one tree species and AB CD because there are about 50,000 species of tropical trees, it seems that many tropical (a) Low diversity (b) High diversity insect species must exist. Erwin estimates FIGURE 4-4 Letters (A, B, C, and so forth) represent species living in © Jones & Bartlett anLearning, area: (a) low diversity LLC at both the local and regional scales; (b)© hiJonesgh & Bartlettthe insect Learning, species on LLC Earth at more than NOT FOR SALE ORdiversity DISTRIBUTION at both scales. NOT FOR SALE30 ORmillion. DISTRIBUTION 110 Chapter 4 The Distribution of Life on Earth 2nd pAGES © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION.

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FORHow SALE ORDoes DISTRIBUTION Biodiversity AffectNOT FOR the SALE OR DISTRIBUTION Case Provisioning of Ecosystem Services? Study © Jones & Bartlett Learning, LLC © Jones & Bartlett4- Learning,1 LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION ver the past 50 years, humans have changed “By affecting the magnitude, pace, and ecosystems more rapidly and extensively than temporal continuity by which energy and Oin any comparable period of time in human materials are circulated through ecosys- Visit history, largely to meet rapidly growing demands tems, biodiversity influences the provision for food,© Jones fresh water, & Bartlett timber, fiber,Learning, and fuel. LLC This of regulating© ecosystem Jones &services, Bartlett such Learning, as www.environment.jbpub.com LLC has resultedNOT FORin a substantial SALE OR and DISTRIBUTIONlargely irreversible pollination andNOT seed FOR dispersal SALE of ORuseful DISTRIBUTION for more information loss in the diversity of life on earth. The first major plants, regulation of climatic conditions finding of the Millennium Ecosystem Assessment suitable to humans and the animals and (MA, 2005a) clearly links the rapid and wide- plants they consider important, the con- spread loss of biodiversity on Earth to the growing trol of agricultural pests and diseases, and © Jones &intensity Bartlett of many Learning, human pressures LLC on biodiversity. © Jonesthe regulation & Bartlett of human Learning, health. Also, LLC by NOT FORAccording SALE OR to the DISTRIBUTION MA’s Biodiversity Synthesis (MA, NOTaffecting FOR SALEnutrient ORand DISTRIBUTIONwater cycling, and 2005b), the most important direct drivers of bio- soil formation and fertility, biodiversity diversity loss and ecosystem service changes are indirectly supports the production of habitat change (such as land use changes or physi- food, fiber, potable water, shelter, and cal modification of rivers), climate change, inva- medicines.” (Diaz, 2010). sive alien species, over©exploitation, Jones & andBartlett pollution. Learning, LLC © Jones & Bartlett Learning, LLC Thus, biodiversity lossNOT is linked FOR to SALE“the degrada OR DISTRIBUTION- Based on available evidence, it is difficult,NOT FOR if almost SALE OR DISTRIBUTION tion of many ecosystem services [and] could grow impossible, to conclude how many species are significantly worse during the first half of this cen- needed to preserve different ecosystem services. tury [ . . . ]” (MA, 2005b). However, moral reasons and the precautionary The Millennium Ecosystem Assessment indi- principle suggest that in all ecosystems as many cates© that Jones human & activities Bartlett over Learning, the last 50 LLC years existing species as© Jonespossible &should Bartlett be preserved. Learning, LLC have NOTaffected FOR ecosystems SALE ORacross DISTRIBUTION the globe more In general, becauseNOT most FOR ecosystem SALE servicesOR DISTRIBUTION are quickly and profoundly than any other time. In provided at the local scale, if we are to preserve fact, we are now in the midst of one of the major the regulating and supporting services that eco- extinction events on Earth. The report states: systems provide to humans, conservation efforts “Appropriating major parts of the energy flow need to focus on preserving or restoring their bi- © Jones &through Bartlett the foodLearning, web and LLC altering the fabric of ©otic Jones integrity & (whetherBartlett inherently Learning, species-poor LLC or NOT FORthe SALE land coverOR DISTRIBUTION to favor the species of greatest NOTspecies-rich), FOR ratherSALE than OR on DISTRIBUTION simply maximizing the value have increased the rate of species extinction number of species present (Diaz, 2010). 100 to 1,000 times the rate before human domi- Regarding the decrease of ecosystem services nance on Earth.” Current trends, such as popula- as a result of rapid biodiversity loss, not all com- tion growth and climate change, affect ecosystems munities will be similarly affected. In fact, it is and the biodiversity ©that Jones underpins & Bartlett these eco Learning, more LLC likely that people who rely most© Jones directly & on Bartlett Learning, LLC systems negatively; yet,NOT without FOR major SALE interven OR DISTRIBUTION- ecosystem services, such as subsistenceNOT FOR farmers SALE OR DISTRIBUTION tion, the threat to global biodiversity will worsen. and fishers, the rural poor, and traditional societ- In addition to the moral reasons to preserve ies, face the most serious and immediate risks. In biodiversity for its own sake, biodiversity provides large part this results from these individuals and a plethora of ecosystem services that are critical to communities relying most directly on the benefits not only© Jones overall human& Bartlett well-being Learning, but also our LLC very provided by the biodiversity© Jones &of Bartlettnatural ecosystems Learning, LLC survivalNOT on FORearth. BiodiversitySALE OR can DISTRIBUTION affect ecosystem in terms of foodNOT security, FOR sustained SALE access OR DISTRIBUTIONto me- services both directly and indirectly. Directly, hu- dicinal goods, construction materials, and fuel. mans derive most of their essential food and fibers Furthermore, these communities and individu- from animals and plants. More indirectly, biodiver- als are the most likely to suffer from storms and sity can affect the provision of ecosystem services floods that may increase as a result of ecosystem © Jones &through Bartlett its influence Learning, on ecosystemLLC processes that ©degradation. Jones & Finally, Bartlett less privilegedLearning, socioeconomic LLC NOT FORare SALE essential OR to DISTRIBUTIONEarth’s life support systems. NOTsectors FOR are also SALE less ableOR toDISTRIBUTION substitute purchased 111 2nd pAGES © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION.

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FORCas SALEe ORHow DISTRIBUTION Does BiodiversityNOT FOR Affect SALE OR the DISTRIBUTION Study Provisioning of Ecosystem Services? 4-1 © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION goods and services and have less purchasing power came into force on December 29, 1993, during the and often less political power. Thus, the loss of 1992 earth summit in Rio de Janeiro. The United biodiversity-dependent ecosystem services is likely Nations declared 2010 as the International Year of to accentuate inequality and marginalization of Biodiversity to help draw attention to the impor- © Jonesthe most& Bartlett vulnerable Learning, sectors of society.LLC tance© of Jones global biodiversity& Bartlett conservation Learning, efforts. LLC NOT FORHowever, SALE ORduring DISTRIBUTION the past few decades, more NOT FOR SALE OR DISTRIBUTION people have become aware of the impact on bio References diversity and the threats of those impacts on Millennium Ecosystem Assessment (MA). 2005a. Ecosystems critical ecosystem services. Many countries have and human well-being: Synthesis. Island Press, Washing- biodiversity protection programs of varying de- ton, DC. © Jones & Bartlett Learning, LLC © Jones &Millennium Bartlett Ecosystem Learning, Assessment LLC (MA). 2005b. Ecosystems grees of effectiveness, and several international and human well-being: Biodiversity synthesis. World Re- NOT FOR SALE ORtreaties DISTRIBUTION and agreements coordinate measuresNOT to FOR SALEsources OR Institute, DISTRIBUTION Washington, DC. slow or halt the loss of biodiversity. For example, Diaz S. 2010. Biodiversity and ecosystem services. Online at: http://www.eoearth.org/article/Bio-diversity_and_eco the United Nations Environment Programme has system_services?topic=49575 played a major role in the establishment of major multilateral environmental agreements, including For more information on international efforts: the Convention© Jones on Biodiversity.& Bartlett This Learning, convention LLC http://www.unep.org/iyb/unepwork.asp© Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

2. Ecological ratios. Another method is to cies exist worldwide. Thus, there may be © Jones &use Bartlett well-studied Learning, groups LLC to predict the ©as Jones many &as Bartlett1.6 million Learning, fungus species LLC if NOT FOR SALEdiversity OR of DISTRIBUTIONless studied groups that are NOTthe 6:1 FOR ratio SALE is applicable OR DISTRIBUTION throughout the associated with them. For example, in world. Only 69,000 fungus species have Europe, there are about six fungus spe- been described. cies for each plant species. Plant species 3. Species area curves. The species area have been relatively well described, and curve has been very influential since © Jones & Bartlett Learning,it is estimated LLC that 270,000 plant© speJones- & Bartlettthe 1960s. Learning, Whenever LLC the number of NOT FOR SALE OR DISTRIBUTION NOT FOR SALEspecies OR DISTRIBUTIONis counted in a gradually en- larged area of sampling, the result is a curve as in Figure 4-6. The number of species rises rapidly at first, but it slows © Jones & Bartlett Learning, LLC as the area of© samplingJones & increasesBartlett Learning,be- LLC NOT FOR SALE OR DISTRIBUTION cause the sameNOT species FOR are SALE encountered OR DISTRIBUTION again and again. Repeated surveys in the tropics and temperate areas have shown that small areas of rain forest contain many more species, often © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC more than 100 times more species, NOT FOR SALE OR DISTRIBUTION NOTthan FOR comparable SALE ORareas DISTRIBUTION of temperature forest. By using the known shape of the species area curve, one can predict how many more species will be found © Jones & Bartlett Learning, LLC © Jones & Bartlettin larger Learning, unsampled LLC areas of tropical FIGURE 4-5 Each of the tropical trees in this expanse can be home to hundreds of insect NOT FORspecies SALE. © Photodisc. OR DISTRIBUTION NOT FOR SALEand OR temperate DISTRIBUTION regions. 112 Chapter 4 The Distribution of Life on Earth 2nd pAGES © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION.

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FORCas SALEe ORHellbenders DISTRIBUTION and Alligators:NOT FOR SALE OR DISTRIBUTION Study The Asia-U.S. Connection 4-2 © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION he geographic distribution of species is partly still alive. These include members of the magno- dependent on their biological adaptations, such lia family, which has many species in both eastern Visit Tas how well a species can tolerate cold winters. Asia and eastern North America. In some cases, However, in many cases, the history of a group also the species themselves are very similar, such as www.environment.jbpub.com© Jonesplays & an Bartlett important Learning, role in its current LLC distribution. A the tulip© Jones poplar &that Bartlett occurs in Learning, both regions. LLC Even for more information NOT FORgood exampleSALE ORof this DISTRIBUTION is the presence of some plants someNOT herbs FOR have strikingSALE similarities.OR DISTRIBUTION The medici- and animals in eastern North America. nal herb ginseng has but two closely related spe- As early as 1750, the famous biologist Linnaeus cies, with one occurring in eastern North America noticed a curious similarity between many species and the other in eastern Asia. in eastern North America and species in Eastern What is the cause of this biological connection © Jones & Bartlett Asia.Learning, A century LLC later, Charles Darwin discussed© Jones &between Bartlett Asia Learning, and eastern LLCNorth America? Many NOT FOR SALE ORthis DISTRIBUTION relationship as well. For example, a giantNOT sal -FOR peopleSALE have OR suggested DISTRIBUTION the North American plants amander called the hellbender, found only in the and animals may have colonized North America southern Appalachian region, belongs to a sala- in the same way as the American Indians. These mander family with all of its other species in Asia early arrivals migrated across the Bering Sea land (Figure CS 4-1). Similarly, there are only two species bridge from Asia through Alaska several thousand of alligators© Jonesin the world: & Bartlett the American Learning, alligator, LLC years ago; however, the© veryJones ancient & Bartlettgeological Learning,age LLC which is foundNOT throughout FOR SALE the southeasternOR DISTRIBUTION United of nearly all of these NOTgroups FOR suggest SALE that they OR be DISTRIBUTION- States, and the Chinese alligator. Primitive fishes came separated much longer than a few thousand also show this pattern. The paddlefish is an archaic years ago. Paleobiologists have found that about fish with a long snout able to detect magnetic fields 40 million years ago there was a land-bridge of its prey in murky waters. The only species of this connection across the North Atlantic. It ranged © Jonesfamily & Bartlettoutside of Learning,the United States LLC occurs in the across© Jonesnorthern & Asia Bartlett through Learning, northern EuropeLLC NOT FORYangtze SALE River ORsystem DISTRIBUTION of China. intoNOT Greenland FOR andSALE northern OR DISTRIBUTION Canada. The cli- An even more striking relationship is seen mate of the Earth was much warmer at this time, among plants: the broadleaf deciduous forests of so it permitted the migration of species adapted to eastern Asia and eastern North America have a warm climates. By 30 million years ago, the Earth great resemblance to one another. Most notable had cooled to the point where such migration was © Jones & Bartlett areLearning, similarities LLC among primitive flowering© plants, Jones &no Bartlett longer possible. Learning, These LLC groups have been iso- NOT FOR SALE ORdescended DISTRIBUTION from plant families that appearedNOT more FOR latedSALE from OR Asia DISTRIBUTION ever since. than 70 million years ago when dinosaurs were This example illustrates how understanding the history of life helps us value its preservation. We see that many of the species that constitute the eastern North American forests are part of a very © Jones & Bartlett Learning, LLC ancient ecosystem. These© Jones species &belong Bartlett to groups Learning, LLC NOT FOR SALE OR DISTRIBUTIONwith a very long evolutionaryNOT FOR heritage, SALE and OR they DISTRIBUTION contain very ancient genetic diversity.

Questions © Jones & Bartlett Learning, LLC 1.© Name Jones three & speciesBartlett that Learning, might be called LLC “living fossils” because they have a very long NOT FOR SALE OR DISTRIBUTION NOTevolutionary FOR SALE heritage. OR DISTRIBUTION 2. Botanists have long noted that ornamental plants from eastern Asia are among the easiest plants for landscapers to cultivate in eastern © Jones & Bartlett CLearning,S 4-1 FIGURE 1 Hellben LLCder salamander. © Brad Moon. © Jones & BartlettNorth America.Learning, Why LLC is this? NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 113 2nd pAGES © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION.

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR sitySALE are ORorganized DISTRIBUTION into populations, and all Area sampled, tropical forest of the populations of a certain geographic Estimated curve, tropical forest area form a community. In the remainder Well studied, temperate forest of this chapter, we briefly describe some of the broad types of natural communities that © Jones & Bartlett Learning, LLC occur on Earth today.© Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

4.3 Biomes and Communities A biome is a large-scale category that includes

© JonesNumber of species & Bartlett Learning, LLC many© communitiesJones & Bartlett of a similar Learning, nature. LLCMany NOT FOR SALE OR DISTRIBUTION thousandsNOT FOR of communities SALE OR exist DISTRIBUTION on the Earth, but rather than describe each in detail, we examine the basic categories into which communities can be grouped. © Jones & Bartlett Learning, LLCArea occupied © Jones & BartlettThe most Learning, basic distinction LLC is between ter- NOT FOR SALE ORFIGUR DISTRIBUTIONE 4-6 A species area curve plots the number of species foundNOT in FOR restrialSALE (land)-OR DISTRIBUTION and aquatic (water)-dwelling increasingly larger areas. The temperate forests are well studied compared communities. There are seven major types to tropical forests. Only small areas have been examined in most tropical forests so data are derived from extrapolated projections as indicated by of terrestrial biomes and two major types of the dashed line. aquatic biomes: © Jones & Bartlett Learning, LLC 1. Terrestrial. Tundra,© Jones grassland, & Bartlett savanna, Learning, LLC BiodiversityNOT Today: FOR A SALERare Wealth OR inDISTRIBUTION Time desert, taiga, NOTtemperate FOR forest, SALE tropical OR DISTRIBUTION All methods of estimating global biodiversity forest (including tropical rain forests) involve a certain amount of extrapolation; so 2. Aquatic. Marine, freshwater understandably, there is still wide disagree- Both terrestrial and aquatic biomes (and thus ment over how many species exist. Estimates the communities within them) are largely de- © Jonesrange & fromBartlett as low Learning, as 3 million LLC species to as high © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION terminedNOT FORby climate, SALE especially OR DISTRIBUTION temperature. as 100 million or more. However, biologists Climate is so important because it affects many generally agree that fewer species live in the aspects of the physical environment: rainfall, ocean than on land. Estimates for the ocean air and water temperature, soil conditions, and range from 1 million to 10 million species. De- so forth. However, secondary factors such as spite having fewer species, however, the oceans © Jones & Bartlett Learning, LLC © Jones &local Bartlett nutrient Learning, availability LLC are also important. have more fundamental biodiversity: 32 phyla NOT FOR SALE OR DISTRIBUTION NOT FOR InSALE all cases, OR biomes DISTRIBUTION illustrate the key point that are found in the oceans compared with just species often will adapt to physical conditions 12 phyla on land. A phylum, such as echino- in similar ways, no matter what their evolu- derms or mollusks, is a much more distinct tionary heritage. A desert biome in the western taxonomic unit of biodiversity than a species. United States looks superficially similar to a Whatever© Jones the &exact Bartlett number Learning, of species LLC © Jones & Bartlett Learning, LLC desert biome in North Africa even though the today, theNOT fossil FOR record SALE indicates OR DISTRIBUTIONthat we live NOT FOR SALE OR DISTRIBUTION plants have different ancestries. during a special time of Earth’s history. De- tailed compilations of fossil data show that the number of families in the oceans has gen- Terrestrial Biomes © Joneserally & Bartlettincreased Learning, through timeLLC (Figure 4-7). Of the© Jones seven basic & Bartlett land biome Learning, types commonly LLC Evolution has produced new families that NOT FOR SALE OR DISTRIBUTION distinguishedNOT FOR (tropical SALE forests,OR DISTRIBUTION savanna, grass- have added to overall biodiversity. Estimates lands, deserts, temperate forests, taiga, and based on species produce similar results. We tundra—each of these is described and illus- apparently live at a time when global bio trated), the tundra and desert biomes repre- diversity is near or at its all-time peak. As we sent adaptations to the extreme conditions of © Jones & Bartlett discussedLearning, in ourLLC review of the biosphere,© Jonesthe &very Bartlett low temperature Learning, and LLC low water, respec- NOT FOR SALE ORindividual DISTRIBUTION organisms composing this NOTdiver -FOR tively.SALE Not OR surprisingly, DISTRIBUTION communities in these 114 Chapter 4 The Distribution of Life on Earth 2nd pAGES © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION.

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC GEOLOGICAL CarboniferousNOT FOR SALEQuaternary OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTIONPERIODS Devonian Cretaceous Silurian Jurassic Ordovician Triassic Cambrian Permian Tertiary

800 © Jones &Mass Bartlett extinctions Learning, LLC © Jones & Bartlett Learning, LLC NOT600 FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION ? 400

of marine animals 200 © Jones & BartlettNumber of families Learning, LLC © Jones & Bartlett Learning, LLC 0 NOT FOR SALE OR570 DISTRIBUTION 505 438 286360 208 NOT65144 FOR 0 SALE OR DISTRIBUTION 408 245 2 Millions of years ago FIGURE 4-7 The number of families in the ocean has generally increased until the present. Five mass extinctions have temporarily lowered biodiversity. Will a sixth mass extinction occur in the © Jones & Bartlett Learning,near future? LLC Source: Modified from D. Raup, J. Sepkoski.© M assJones extinctions & in thBartlette marine fossil Learning, record. LLC NOT FOR SALE OR DISTRIBUTIONScience 1982;215:1501–1503. NOT FOR SALE OR DISTRIBUTION

biomes tend to have the least number of spe- and increasing latitude; similar changes result cies because organisms have difficulty adapt- in both cases. In addition, note the importance ing to the extreme© physical Jones &conditions. Bartlett Learning,In of precipitation, LLC ranging from ©the Jones very moist & Bartlett Learning, LLC contrast, the tropicalNOT rain FOR forests SALE tend ORto be DISTRIBUTION equatorial regions to the desert NOTbiome. FOR A more SALE OR DISTRIBUTION richest in species, in part because the tropics detailed global view in Figure 4-9 shows some have the most moderate overall conditions. of the true complexities of the latitudinal pat- Figure 4-8 illustrates the approximate dis- tern. For example, tropical forests are not al- tribution of some of the major land biomes by ways neatly confined to equatorial areas. precipitation,© Jones altitude, & Bartlett and latitude. Learning, This LLCfigure We now describe© Jones seven & Bartlettmajor terrestrial Learning, LLC demonstratesNOT FOR the SALE importance OR DISTRIBUTION of temperature, biomes (listed NOTin approximate FOR SALE order OR DISTRIBUTIONgoing which decreases with both increasing altitude, from the equator to the poles).

Feet Meters © Jones & Bartlett20,000 6,000 Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

5,000 Polar 15,000 Humid subtropical 4,000 Humid © JonesTundra & Bartlett Learning,continental LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTIONSubarctic NOT FOR SALE OR DISTRIBUTION 10,000 3,000 Elevation

2,000 Coniferous and deciduous forest 5,000© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR1,000 SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Dry

00 0 30 60 90 Tropical Tropical Latitude in degrees © Jones & Bartlett Learning,wet LLCwet & dry © Jones & Bartlett Learning, LLC NOT FORFIGUR SALEE 4-8 Veg ORetation DISTRIBUTION changes with altitude in the same way as with latitude becauseNOT both FORchanges arSALEe associated OR with dDISTRIBUTIONecreasing temperatures. 4.3 Biomes and Communities 115 2nd pAGES © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION.

Ice

Equator © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Tropic of Capricorn

Tundra Temperate grassland Tropical scrub forest

Mountains Semidesert, Tropical rain forest, © Jones(complex & zonation) Bartlett Learning, LLC arid grassland © Jones & Bartletttropical Learning, evergreen forestLLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Boreal forest (taiga), Desert Tropical deciduous forest montane coniferous forest

Temperate forest Chaparral/Mediterranean Tropical savanna, thorn forest © Jones &FIGUR BartlettE 4-9 The m Learning,ajor terrestrial biomes LLC of the world. © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Tropical Forests rare throughout the year, such as areas of Cen- Although rain forests are the best known kind tral America and central Africa. Because of the of tropical forest, there are actually several moisture limitations, photosynthesis and plant types. Tropical© Jones seasonal & Bartlett forests Learning, occur in dry LLC productivity are only© Jonesabout one-third & Bartlett that Learning, of LLC areas of theNOT tropics, FOR where SALE pronounced OR DISTRIBUTION dry pe- the tropical rain forest.NOT FOR SALE OR DISTRIBUTION riods cause the trees to be deciduous (drop their Tropical forests are found on most major leaves). Tropical seasonal forests are common continents, mainly in equatorial regions (Fig- in parts of Southeast Asia, especially India, ure 4-9). These represent the most complex © Joneswhere & Bartlettthey are often Learning, called “monsoon LLC forests” and© diverse Jones biome, & Bartlett containing Learning, perhaps LLC more because the rain-bearing monsoon winds carry than 50% of the world’s species while occupy- NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION the moisture that restarts forest growth after ing only 7% of the land area. Unfortunately, the dry season. In contrast, tropical rain for- people have deforested approximately half of ests are evergreen forests where plants show no this area; and consequently, many rain forest major seasonal changes. Another type of tropi- species are on the brink of extinction. The high © Jones & Bartlett calLearning, forest is the LLC tropical woodland. This ©occurs Jones &biodiversity Bartlett Learning, of tropical LLCrain forests is partly NOT FOR SALE ORin DISTRIBUTIONparts of the tropics where rainfall is relativelyNOT FOR dueSALE to theOR relatively DISTRIBUTION constant temperatures 116 Chapter 4 The Distribution of Life on Earth 2nd pAGES © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION.

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FORand SALE high waterOR DISTRIBUTION availability: daily and seasonal NOTlevel must FOR have SALE special OR adaptations DISTRIBUTION for coping changes (fluctuations) are usually less than with the lack of sunlight. For example, many a total of 5°C (9°F). Rainfall is very heavy, plants have very broad leaves (such as the ranging from 200 to 450 centimeters per year common “elephant ear” plant) to maximize (80 to 175 inches). In comparison, Seattle, surface area and very dark green pigmentation Washington, receives© anJones average & Bartlettof 100 cen Learning,- (chlorophyll) LLC to maximize light© Jonesabsorption. & Bartlett Learning, LLC timeters (37 inches) NOTof precipitation FOR SALE annually. OR DISTRIBUTION Another common adaptation isNOT found FOR among SALE OR DISTRIBUTION The average temperature of the tropical rain epiphytes (plants that grow on the branches of forest biome is about 25°C (77°F to 80°F). In trees) and vines, which grow up tree trunks to comparison, New Orleans, Louisiana, has an capture light in gaps high in the canopy. average© Jones temperature & Bartlett of just Learning,20°C (68°F). LLC The high species© Jones diversity & Bartlett of tropical Learning, rain LLC ThisNOT lack FOR of pronounced SALE OR seasonal DISTRIBUTION tempera forests has also NOTled to FOR the misconception SALE OR DISTRIBUTION that tures, including longer days and more direct they must have very fertile soils. In fact, the sunlight, provides more opportunity for plant soils here are quite poor (low in phosphorus, growth and productivity in this biome. The nitrogen, and other nutrients) because they are result is an ecosystem of very high species di- depleted by the intense competition among the © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC versity and structural complexity (Figure 4-10). abundant fast-growing plants for nutrients. The NOT FORThis SALE structural OR DISTRIBUTION complexity is seen in the many NOThot, humid FOR climateSALE makesOR DISTRIBUTION tropical rain forests layers of trees forming a multistoried canopy. an ideal environment for bacteria, fungi, ter- The canopy blocks out most of the sunlight mites, and other soil organisms, which quickly so that, in contrast to popular conception, the decompose matter on the forest floor. Most forest floor is relatively© Jones dark and & Bartlettdoes not sup Learning,- of the LLC free nutrients remaining ©in Jones the soil & are Bartlett Learning, LLC port dense vegetation.NOT Plants FOR living SALE at ground OR DISTRIBUTION leached away by the high rainfall.NOT The FOR result SALE is OR DISTRIBUTION that nearly all nutrients are tied up in the bio- mass of the plants and animals living in the rain forest. The only way to release these nutrients for farming is to cut and burn the vegetation by © Jones & Bartlett Learning, LLC “slash-and-burn”© Jonesagriculture. & Bartlett Unlike the Learning, tem- LLC NOT FOR SALE OR DISTRIBUTION perate forest biomeNOT (discussed FOR SALE later), OR tropical DISTRIBUTION forests on different continents vary widely in the genera and families of plants that compose them. This is probably a result of the relative © Jones & Bartlett Learning, LLC ©isolation Jones and & rapidBartlett evolution Learning, of species LLC in trop- NOT FOR SALE OR DISTRIBUTION NOTical ecosystems. FOR SALE In addition, OR DISTRIBUTION most tropical forest plants (especially trees) belong to botanical families that are rarely, if ever, found in temperate latitudes. This gives the rain forest its exotic appearance to visitors from North America © Jones & Bartlett Learning,and otherLLC temperate latitudes. © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTIONIn most ecosystems, there isNOT a strong FOR cor SALE- OR DISTRIBUTION relation between the diversity of plant species and the diversity of animal species; so it is not surprising that the diverse tropical plant © Jones & Bartlett Learning, LLC life supports a ©proportionately Jones & Bartlett rich diversity Learning, LLC NOT FOR SALE OR DISTRIBUTION of animal life. NOTIt has FORbeen SALEestimated, OR for DISTRIBUTION example, that more than 90% of earth’s insect species are found in the rain forests. This high diversity is true for many other animal groups, such as mammals and especially birds, which © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC FIGURE 4-10 The complex (multilayered) structure of a tropical rain are much more diverse in the tropics than NOT FORfor SALEest. © Photodisc. OR DISTRIBUTION NOTother biomesFOR SALE (Figur eOR 4-11 DISTRIBUTION). 4.3 Biomes and Communities 117 2nd pAGES © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION.

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR liaSALE and AsiaOR DISTRIBUTION(Figure 4-9). These regions are warm and have prolonged dry seasons with annual rainfall averaging 90 to 150 cm (35 to 60 inches). Such climatic conditions support vegetation of open grasslands with scattered © Jones & Bartlett Learning, LLC shrubs and trees (see© FigurJonese 4-12 & ).Bartlett The grasses Learning, LLC NOT FOR SALE OR DISTRIBUTIONgrow rapidly duringNOT the FOR rainy SALE season OR and DISTRIBUTION dry up during the dry season while the few trees survive by growing deep root systems to access groundwater supplies. In areas of © Jones & Bartlett Learning, LLC increasing© Jones rainfall, & Bartlett woodland Learning, begins to replaceLLC NOT FOR SALE OR DISTRIBUTION the NOTsavanna FOR as SALEtree density OR DISTRIBUTION increases. Some savanna-like environments with dense scrubby evergreen vegetation are called chaparral. Examples occur in California and the Mediter- ranean region (Figure 4-9). © Jones & Bartlett Learning, LLC © Jones & BartlettMany people Learning, are familiar LLC with the big-game NOT FOR SALE OR DISTRIBUTION NOT FOR animalsSALE ORof theDISTRIBUTION African savanna, including such large herbivores as wildebeests, zebra, rhinoceroses, and buffalo. The most notori- ous predators of these creatures are the prides of lions that roam the savanna. Savannas also © Jones & Bartlett Learning, LLC support many species© Jones of insects, & Bartlett including Learning, LLC NOT FOR SALE OR DISTRIBUTIONants, beetles, grasshoppers,NOT FOR and SALE termites. OR The DISTRIBUTION termites may be familiar because of the huge mounds they build. These mounds are impor- FIGURE 4-11 Macaws range from southern Mexico down into central South America. This is a blue and gold macaw. © Photodisc. tant to the savanna ecosystem because they © Jones & Bartlett Learning, LLC are ©made Jones of digested& Bartlett plant Learning, material. LLC Their NOT FORSavannas SALE OR DISTRIBUTION constructionNOT FOR accelerates SALE OR the DISTRIBUTION breakdown of these nutrients, thereby enhancing soil qual- Savannas occur in tropical and subtropical ity. The deep and complex passageways in areas that are not wet enough to support rain these mounds help carry badly needed rain- forests. Probably the best known of these are water into the soil, instead of the water being the savannas of Africa and South America, but © Jones & Bartlett Learning, LLC © Jones &carried Bartlett away Learning, or evaporating. LLC they also occur in tropical regions of Austra- NOT FOR SALE OR DISTRIBUTION NOT FOR SALEDuring OR the DISTRIBUTION dry season, savannas periodi- cally experience large grass fires. The vegetation has evolved ways to be fire resistant, such as rapid regeneration from unburned roots. People have often taken advantage of this pro- © Jones & Bartlett Learning, LLC cess by purposely setting© Jones fires &to Bartlettpromote Learning,new LLC NOT FOR SALE OR DISTRIBUTIONgrowth that is favorableNOT for FOR grazing SALE animals. OR DISTRIBUTION

Deserts Deserts occur where rainfall is very scarce, © Jones & Bartlett Learning, LLC less ©than Jones 25 centimeters & Bartlett (10 Learning, inches) per LLC year. NOT FOR SALE OR DISTRIBUTION In warmNOT regions,FOR SALE the problem OR DISTRIBUTION of scarce water is aggravated by high evaporation and water loss. As a result, deserts have among the low- est rates of plant growth and productivity of any area on earth (see our review of the bio- © Jones & Bartlett Learning, LLC © Jones &sphere). Bartlett An Learning, important LLC consequence is that NOT FORFIGUR SALEE 4-12 Savanna OR in DISTRIBUTIONKenya. © Photodisc. NOT FOR desertSALE ecosystems OR DISTRIBUTION will take a longer time to 118 Chapter 4 The Distribution of Life on Earth 2nd pAGES © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION.

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FORrecover SALE from OR DISTRIBUTIONhuman disturbances, often cen- NOT FOR SALE OR DISTRIBUTION turies, than nearly all other ecosystems. The most extreme deserts, including the Sahara of Africa and Gobi of Mongolia, average less than 10 cm (4 inches) of rain per year, sometimes going for years© withJones no &rain Bartlett at all ( FigLearning,- LLC © Jones & Bartlett Learning, LLC ure 4-13). Some areasNOT of theFOR Atacama SALE DesertOR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION in Chile reportedly have never seen recorded rainfall and only occasional cloud cover. As a result, extreme deserts support very little life of any kind.© Jones Most &extreme Bartlett deserts Learning, occur in LLCa belt © Jones & Bartlett Learning, LLC that NOTis about FOR 20 SALEto 30 degrees OR DISTRIBUTION latitude north NOT FOR SALE OR DISTRIBUTION and south of the equator (see Figure 4-9). This is because rising hot equatorial air produces heavy tropical rains so that when the cooler air sinks to the Earth at about 20 to 30 degrees FIGURE 4-13 The lack of rain means almost nothing can grow in this part of the Sahara desert in Morocco. © CJ Photography/ShutterStock, Inc. © Jones &north Bartlett and south Learning, latitude, LLC it is quite arid. © Jones & Bartlett Learning, LLC NOT FOR SALESemideserts, OR DISTRIBUTION such as those of the south- NOT FOR SALE OR DISTRIBUTION western United States, are less extreme and re- Annual plants are common in deserts. In these ceive between 10 and 25 cm (4 to 10 inches) of plants, the adult dies and the species survives rainfall per year. These extra few inches of rain as seeds that germinate when enough rainfall can support a fairly© diverse Jones array & Bartlett of species, Learning, occurs. LLC Small trees, such as the© JonesJoshua &tree Bartlett Learning, LLC usually typified by widely spaced, thorny NOT FOR SALE OR DISTRIBUTIONand mesquite, can occur where NOTwater FOR supplies SALE OR DISTRIBUTION “desert scrub” vegetation. Desert plants, often are adequate, but large trees such as the des- called xerophytes, have many interesting ad- ert cottonwood occur only at oases (springs) aptations that allow them to survive the scarce or dry riverbeds where deep groundwater and unpredictable water supply (Figure 4-14). supplies are present. Cacti© are Jones the most & Bartlett familiar Learning,example to LLCmany Animal adaptations© Jones are & Bartlettoften similar Learning, to LLC people;NOT water-storing FOR SALE plants OR suchDISTRIBUTION as these are those of plants. NOTNearly FOR all animals SALE have OR mechDISTRIBUTION- called succulents. Other adaptations can in- anisms that increase the efficiency by which clude the following: water is retained. The ability of the camel to • Wide spacing of plants allows maxi- go for weeks without drinking is legendary. Desert animals tend to be small, with some © Jones & Bartlettmum Learning, moisture per LLC plant. © Jones & Bartlett Learning, LLC exceptions, such as the camel, mule deer, and NOT FOR SALE• Hard OR DISTRIBUTIONexteriors maximize water NOT FOR SALE OR DISTRIBUTION retention. • Thorns reduce the consumption of the plants by animals seeking to ex- tract the stored water. • Deciduous plants© Jones shed & leaves Bartlett during Learning, LLC © Jones & Bartlett Learning, LLC dry periods toNOT conserve FOR water.SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION • Nighttime gas exchange (transpira- tion) is favored. • Rapid growth occurs during brief pe- © Jonesriods of & rainfall. Bartlett Learning, LLC © Jones & Bartlett Learning, LLC • NOTVery FOR long SALE tap roots, OR especially DISTRIBUTION in trees, NOT FOR SALE OR DISTRIBUTION can reach into deep underground water supplies. • Nearly all perennial plant species can go dormant (a time of reduced photo- © Jones & Bartlettsynthesis) Learning, during LLC periods of very high © Jones & Bartlett Learning, LLC NOT FOR SALEtemperature. OR DISTRIBUTION FNOTIGURE 4-14 FOR A vari etySALE of cacti anORd oth erDISTRIBUTION semidesert plants. © J. Norman Reid/ShutterStock, Inc. 4.3 Biomes and Communities 119 2nd pAGES © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION.

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE ORkangaroo. DISTRIBUTION Reptiles are generally more NOTabun -FOR duringSALE theOR dry DISTRIBUTION season. Trees, although not dant than warm-blooded animals. Reptiles common, occur locally along stream banks are ectothermic; their behavior regulates their and steep slopes where shade from the sun pro- body temperatures. By cooling their body tem- vides more moisture and protection from fires. peratures, they can reduce their energy needs to People have drastically altered much of wait out© the Jones dry seasons & Bartlett or low Learning, food sources. LLC this biome because© economically Jones & Bartlett this is ourLearning, LLC Also veryNOT common FOR isSALE the habit OR ofDISTRIBUTION restricting most important biome.NOT Temperate FOR SALE grasslands OR DISTRIBUTION activity to nighttime, with daytime spent in provide the richest land in the world for grain deep burrows as a means of escaping the heat. crops such as wheat and grazing for sheep, Desert rattlesnakes and small rodents illustrate cattle, and other food animals. For exam- © Jonesthis. & Many Bartlett animals, Learning, such as LLC the desert toad, ple, ©it Jonesis estimated & Bartlett that farming Learning, and grazing LLC NOT FORtake thisSALE one ORstep DISTRIBUTIONfarther and enter a dormant haveNOT drastically FOR SALEmodified OR DISTRIBUTIONmore than 95% of stage for long periods, becoming revived dur- the original Great Plains biome in the last ing the brief periods of rain. It is during this 200 years. Although many species of grass period that reproduction usually occurs. and the insects supported in the great prairie were lost before they could be counted accu- Temperate Grasslands © Jones & Bartlett Learning, LLC © Jones &rately Bartlett or their Learning, complex LLC relationships under- NOT FOR SALE ORTemperate DISTRIBUTION regions with scarce rainfall, NOTabout FOR stood,SALE modern OR DISTRIBUTION prairie grass species diversity 25 to 75 cm (10 to 30 inches) per year, tend to have been reduced from approximately more have grasses and other herbaceous forms as the than 200 distinct species to about 20 species. most prominent plants (Figure 4-15). Examples In recent years, individual landowners have include the© JonesGreat Plains & Bartlett of North Learning, America, the LLC taken an interest in© reintroducing Jones & Bartlett a wider Learning,di- LLC pampas of South America, and the steppes of NOT FOR SALE OR DISTRIBUTIONversity of prairie grasses,NOT FORbut overgrazing SALE OR still DISTRIBUTION Russia (see Figure 4-9). Tall-grass prairies are threatens the once highly impressive biodiver- grasslands, with plants often standing more sity of the Great Plains. than 1 meter tall, of the moister areas. Short- Burrowing animals such as prairie dogs grass prairies consist of clumps of short grasses, populate grasslands in their natural state, and © Jonessuch & as Bartlett bunchgrass, Learning, that grow LLC in drier regions. native© Jonesherbivorous & Bartlett mammals, Learning, for example LLC NOT FORThe organicSALE ORmatter DISTRIBUTION added annually when the bisonNOT in North FOR America,SALE OR extensively DISTRIBUTION graze the grasses die forms the rich soils of grasslands. area. Although grasses have evolved to tolerate The grass roots and the relative lack of rain significant amounts of grazing, the introduc- hold the soils in place. Because of the aridity, tion of nonnative grazers such as cattle has led grasslands regularly experience fires, especially © Jones & Bartlett Learning, LLC © Jones &to Bartlett overgrazing Learning, because, LLCunlike native grazers, NOT FOR SALE OR DISTRIBUTION NOT FOR theySALE tend OR to eatDISTRIBUTION the plant faster than it grows. It may not always be obvious that nonnative grazers are more destructive than native species. For instance, why did not the millions of bison that once roamed the American Plains © Jones & Bartlett Learning, LLC cause just as much impact© Jones as some & Bartlett herded catLearning,- LLC NOT FOR SALE OR DISTRIBUTIONtle do now? In fact, bisonNOT could FOR cause SALE localized, OR DISTRIBUTION temporary damage in the sense of short-term overgrazing, but the bison were migratory and moved on to other areas, allowing the plants © Jones & Bartlett Learning, LLC to grow© Jones back. In& Bartlettaddition, bisonLearning, under naturalLLC NOT FOR SALE OR DISTRIBUTION conditionsNOT FOR could SALE be more OR selectiveDISTRIBUTION than do- mesticated cattle in what they ate, focusing, for instance, on just certain tender or tasty parts of a plant. Some bison would also selectively feed on a variety of leaves, twigs, and bark. The © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC FIGURE 4-15 A rancher and his son look out over their herd of cattle on temperate grasslands. overall effect was that bison could live sustain- NOT FORCourtesy SALE of Tim M cCabe/USDAOR DISTRIBUTION Natural Resources Conservation Service. NOT FOR ablySALE in their OR naturalDISTRIBUTION environment. 120 Chapter 4 The Distribution of Life on Earth 2nd pAGES © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION.

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALEAnother OR problem DISTRIBUTION is the invasion of nonna- NOTregions FOR share SALE many OR closely DISTRIBUTION related tree spe- tive grasses, including cheatgrass in the United cies, including the oaks, chestnuts, beeches, States, which replace the native grasses after and birches, indicating a shared common such disturbances as fire and overgrazing. Be- evolutionary heritage dating geologic periods cause of this extensive loss of native grassland when the continents were interconnected (see plants, substantial efforts© Jones have &been Bartlett made toLearning,- our reviewLLC of the dynamic Earth© Jonesand natural & Bartlett Learning, LLC ward the ecological NOTrestoration FOR ofSALE the prairies OR DISTRIBUTION hazards). Within the United States,NOT FORoak and SALE OR DISTRIBUTION in North America. hickory dominate in the Southeast, and beech and maple dominate in the Northeast; how- Temperate Forests ever, substantial numbers of conifers (ever- Temperate© Jones regions & Bartlett with adequate Learning, rainfall, LLC 75 green cone-bearing© Jones trees such & Bartlett as pines) Learning, occur LLC to 150NOT cm FOR(30 to SALE 60 inches) OR perDISTRIBUTION year, support in many of theseNOT forests, FOR mainly SALE as earlyOR DISTRIBUTION colo- forests of broad-leaved deciduous trees that nizers of disturbed areas or on poorer soils to show colorful seasonal changes before drop- which deciduous trees are not well adapted. ping their leaves (Figure 4-16a). The seasonal These forests lack the spectacular diver leaf dropping is an adaptation to the very sity of tropical forests but are still more © Jones &cold Bartlett winters Learning, when water LLC becomes frozen and ©diverse Jones than & Bartlettconiferous Learning, forests. ComparedLLC NOT FORphoto SALEsynthesis OR DISTRIBUTION is difficult or impossible. Ex- NOTwith the FOR tropical SALE rain OR forests DISTRIBUTION to the south, tem- amples are found in Europe, parts of Asia, and perate forests have a well-developed under- the eastern United States (Figure 4-9). These story vegetation of many shrubs, herbs, ferns,

© Jones &(a) Bartlett Learning, LLC © Jones(b) & Bartlett Learning, LLC NOT FORFIGUR SALEE 4-16 (a)OR Colorful DISTRIBUTION fall foliage in an eastern U.S. deciduous forest. © Photos.com.NOT (b) FORCougar. © SALE AbleStock. OR DISTRIBUTION 4.3 Biomes and Communities 121 2nd pAGES © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION.

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE ORmosses, DISTRIBUTION and small trees because so muchNOT light FOR DuringSALE theOR longDISTRIBUTION summer days, plants grow reaches the ground when the tall trees season- rapidly. Marshes, ponds, and lakes are com- ally lose their leaves. In addition, unlike the mon, often forming in depressions carved out rain forest, where much animal life is found by the glaciers present in the area just a few in the trees, a diverse array of species dwells thousand years ago. on the ground.© Jones Large & Bartlett herbivores Learning, include elk LLC Common animals© Jones of the & taigaBartlett include Learning, LLC and deer,NOT and carnivoresFOR SALE include OR DISTRIBUTIONwolves, cou- herbivores, such asNOT moose, FOR elk, SALE deer, and OR the DISTRIBUTION gars, and foxes (Figure 4-16b). snowshoe hare; and carnivores, such as tim- In the eastern United States, this biome ber wolves, brown bears, lynx, and wolver- has been drastically modified throughout ines. The animals have adapted to the cold in © Jonesnearly & Bartlettall of its range. Learning, Europeans LLC cleared these various© Jones ways, &including Bartlett exceptionally Learning, LLC thick NOT FORforests SALE for farming OR DISTRIBUTION during the early years of fur andNOT fat FOR storage SALE abilities OR DISTRIBUTIONthat help sustain colonization. In some areas, especially the them through the long winters. northeastern United States, where the land is Compared with other biomes, the taiga no longer farmed, ecological succession is be- has been less modified by agriculture. One ginning to return the land to its former state. reason is that cleared taiga makes poor crop- © Jones & Bartlett YoungLearning, temperate LLC forests are now common.© Jones &land. Bartlett In addition Learning, to the coldLLC climate and short NOT FOR SALE OR DISTRIBUTION NOT FOR growingSALE ORseason, DISTRIBUTION the thin soils are very acidic Taiga (pH of 4.5 to 5.0) compared with the soils of Taiga, also called coniferous or boreal for- grasslands or temperate forests (pH of 6 to 7). ests, occur in a broad belt in northern North The microbial decay of pine needles and other America ©and Jones Asia (Figure& Bartlett 4-9). Learning, Very few tai LLC- coniferous ground ©litter Jones produce & Bartlett the acidic Learning, LLC gas occur in the Southern Hemisphere because NOT FOR SALE OR DISTRIBUTIONsoil; however, clear-cuttingNOT FOR for SALEtimber ORdrasti DISTRIBUTION- ocean waters mainly occupy these latitudes. cally modifies extensive tracts of the lower- Diversity and plant productivity are relatively latitude taiga. low because of the stress imposed by long, cold winters with little precipitation. Trees are Tundra © Jonesdominated & Bartlett by conifers Learning, (evergreens), LLC which are Arctic© Jonestundra occurs& Bartlett in Canada Learning, and Eurasia’s LLC NOT FORtolerant SALE of dry, OR cold DISTRIBUTION conditions (Figure 4-17). highNOT northern FOR SALElatitudes, OR between DISTRIBUTION the taiga Prominent types of evergreens include spruce, and shores of the polar seas (Figure 4-9). As firs, and pines whose needles conserve water with taiga, little tundra occurs in the South- and withstand freezing better than do leaves. ern Hemisphere because ocean waters occupy © Jones & Bartlett Learning, LLC © Jones &these Bartlett latitudes. Learning, Tundra LLCis the low-lying vege- NOT FOR SALE OR DISTRIBUTION NOT FOR tationSALE that OR occupies DISTRIBUTION an extensive treeless plain whose topsoil is frozen all year except for about 2 months during summer. Below this is permafrost soil, which is frozen all year long. This inhospitable region is not only very cold © Jones & Bartlett Learning, LLC but also very dry. It© receives Jones less& Bartlett than 25 Learning,cm LLC NOT FOR SALE OR DISTRIBUTION(10 inches) per yearNOT, or FORabout SALE the same OR asDISTRIBUTION the desert biome. During the winter, the sun barely rises above the horizon and only for a few hours a day. Few species are able to adapt © Jones & Bartlett Learning, LLC to such© Jones harsh &conditions, Bartlett Learning,and so the LLCtundra NOT FOR SALE OR DISTRIBUTION has NOTrelatively FOR low SALE plant OR species DISTRIBUTION diversity. Not surprisingly, this region also has relatively low plant productivity because of the limited opportunity for photosynthesis. During the brief summer thaw, the tundra © Jones & Bartlett Learning, LLC © Jones &becomes Bartlett an Learning, almost impassable LLC bog, pocketed NOT FORFIGUR SALEE 4-17 Tai ga.OR © Zastavkin/Sh DISTRIBUTIONutterStock, Inc. NOT FOR withSALE countless OR DISTRIBUTION lakes and streams (Figure 4-18). 122 Chapter 4 The Distribution of Life on Earth 2nd pAGES © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION.

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FORLichens SALE (algae OR DISTRIBUTION and fungi symbionts), grasses, NOT FOR SALE OR DISTRIBUTION mosses, and small shrubs are dominant plants. With a growing season of less than 8 weeks, these species must grow and reproduce rapidly. During this period, the tundra teems with life as animals seek© Jones to capitalize & Bartlett on these Learning, LLC © Jones & Bartlett Learning, LLC rich but short-lived NOTplant FORresources. SALE Birds OR ar DISTRIBUTION- NOT FOR SALE OR DISTRIBUTION rive from the south, and animals, including caribou (reindeer), migrate into the area for feeding (Figure 4-18b). The air is filled with billions© Jones of insects. & Bartlett More permanent Learning, residents LLC © Jones & Bartlett Learning, LLC includeNOT the FOR arctic SALE hare, arctic OR DISTRIBUTION fox, and snowy NOT FOR SALE OR DISTRIBUTION owl. Some small rodents such as lemmings survive the winters underground, although they often show drastic population fluctuations. Like the taiga, the harsh nature of this © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC biome has kept it from being modified or oc- (a) NOT FORcupied SALE by OR people DISTRIBUTION to any degree. NOT FOR SALE OR DISTRIBUTION Alpine tundra occurs in lower latitudes where the altitude is sufficiently high (Fig- ure 4-18). Above the tree line on the slopes of mountains, plant© and Jones animal & Bartlett diversity Learning,is LLC © Jones & Bartlett Learning, LLC low. The soil can onlyNOT support FOR plantsSALE similar OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION to those found in the arctic tundra: lichens, grasses, mosses, and shrubs that hug the ground to retain heat and withstand the high winds. The dominant animals are rodents. Mountain goats,© elk,Jones sheep, & Bartlettand bears Learning, are seasonal LLC resi- © Jones & Bartlett Learning, LLC dents.NOT Compared FOR SALEwith the OR boggy DISTRIBUTION soil of the arc- NOT FOR SALE OR DISTRIBUTION tic tundra, alpine tundra soil is well drained.

Aquatic Biomes © Jones &Living Bartlett conditions Learning, in water LLC tend to be much © Jones & Bartlett Learning, LLC NOT FORless SALE harsh OR than DISTRIBUTION on land. The limiting factors in NOT FOR SALE OR DISTRIBUTION aquatic biomes are different in several important ways. Recall that temperature is a limiting factor on land, but water has many fewer temperature fluctuations. In aquatic environments, the water provides© Jones the &added Bartlett benefit Learning, LLC © Jones & Bartlett Learning, LLC of more buoyancy forNOT organisms FOR SALE as support OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION against gravity. The amount of light available in aquatic biomes is a limiting factor in ways that are not experienced on land. Water is a powerful© Jones solvent & andBartlett also readily Learning, carries LLCmany © Jones & Bartlett Learning, LLC substancesNOT FOR in suspension; SALE OR theseDISTRIBUTION substances, NOT FOR SALE OR DISTRIBUTION which range from toxins to nutrients, influence life locally. All of these differences occur (b) because water, as a liquid medium, is much FIGURE 4-18 (a) The Arctic tundra. Courtesy of U.S. Fish & Wildlife Service. denser than the gaseous air. Most importantly, (b) Caribou. © Photodisc. © Jones &perhaps, Bartlett getting Learning, enough LLCwater is not a prob- © Jones & Bartlett Learning, LLC NOT FORlem. SALE Living OR in DISTRIBUTION water eliminates the danger of NOT FOR SALE OR DISTRIBUTION 4.3 Biomes and Communities 123 2nd pAGES © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION.

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE ORdrying DISTRIBUTION out that most land organisms mustNOT face FOR well.SALE The OR marine DISTRIBUTION biome is the largest biome every day. The fact that water in the frozen by far (more than 70% of the Earth’s surface) state floats and expands also is a noteworthy but can be divided relatively easily into the point since this property allows organisms to benthic zone (on the bottom) and the pelagic live in water under the ice even when tempera- zone (in the water column). Because water tures are© below Jones freezing, & Bartlett and also Learning, makes pos LLC- depth and the amount© Jones of light & affect Bartlett the disLearning,- LLC sible life NOTin mud FOR at the SALE bottom OR of DISTRIBUTION a lake, since tribution of organisms,NOT biologists FOR SALE use them OR toDISTRIBUTION most large bodies of water never freeze all the subdivide these zones into smaller zones. way to the bottom. Not surprisingly, life origi- The pelagic zone includes the relatively nated in the shallow oceans and took many shallow water zone over the continental © Jonesmillions & Bartlett of years Learning, to adapt to LLCland. shelves© Jones and the & deep Bartlett ocean Learning,zone. Pelagic LLC crea- NOT FORAquatic SALE communitiesOR DISTRIBUTION do not divide into turesNOT include FOR planktonic SALE OR organisms DISTRIBUTION (floaters), distinctive latitudinal biomes like those found such as diatoms, and nektonic organisms on land. Water readily transports heat, and (swimmers), such as fish, turtles, whales, and this property enables warm currents, such as squids (Figure 4-20). Bottom-dwelling organ- the Gulf Stream, to warm large areas even isms can be considered benthic regardless of © Jones & Bartlett nearLearning, the poles. LLC This prevents a simple ©latitu Jones- &whether Bartlett they Learning, are attached LLC or not. Benthic NOT FOR SALE ORdinal DISTRIBUTION gradient from forming. It is the water’sNOT FOR creaturesSALE OR include DISTRIBUTION burrowers such as worms, salinity that is particularly important in deter- crawlers such as snails, and stationary filter mining what can live in a particular environ- feeders such as barnacles (Figure 4-21). Ben- ment. Therefore, ecologists often designate thic communities (Figure 4-19) are further only two© aquatic Jones biomes:& Bartlett the marineLearning, biome LLC subdivided by depth:© Jones littoral &(shore), Bartlett conti Learning,- LLC and the freshwaterNOT FOR biome SALE (Figur ORe DISTRIBUTION 4-19). nental shelf, and abyssalNOT FOR(deep SALE sea). Littoral OR DISTRIBUTION species have adaptations to avoid drying out. Marine Biome For example, barnacles can tightly seal their Marine water differs from freshwater in con- hard exterior to retain water when the tide taining more dissolved minerals (salts) of goes out. Many other crustaceans dig deeply © Jonesvarious & Bartlett kinds. On Learning, average, marineLLC water has into© the Jones wet sand.& Bartlett The type Learning, of shoreline— LLC NOT FORabout SALE 3.5% salt,OR DISTRIBUTIONmainly sodium chloride, but sandy,NOT muddy, FOR or SALE rocky—subdivides OR DISTRIBUTION the litto- with many hundreds of other materials as ral communities. Deep-water benthic species

NOT FOR SALE OR DISTRIBUTIONFreshwater biome NOT FOR SALEMarine OR biome DISTRIBUTION

Lakes Rivers © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTIONLittoral NOT FORPhotic SALE OR DISTRIBUTION (shore) zone

Continental shelf Pelagic (water column) © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Benthic NOT FOR SALE OR DISTRIBUTION NOT(sea bottom)FOR SALE OR DISTRIBUTION

Abyssal (deep sea) © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC FIGURE 4-19 The two aquatic biomes are freshwater and marine. The marine biome can be divided into benthic NOT FOR SALE OR DISTRIBUTIONand pelagic zones. NOT FOR SALE OR DISTRIBUTION 124 Chapter 4 The Distribution of Life on Earth 2nd pAGES © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION.

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION(b) NOT FOR SALE OR DISTRIBUTION FIGURE 4-21 (a) This bloodworm lives in salt marsh sediments. Some of (b) these worms are free living, whereas others are tube builders. Courtesy of FIGURE 4-20 (a) Diatoms are microscopic phytoplankton responsible for NOAA, National Estuarine Research Reserve. (b) Spider crabs around a deep much of the ocean’s primary production. Courtesy of Dr. Neil Sullivan/ sea vent. Courtesy of NOAA, National Undersea Research Program (NURP). NOAA Corps Collection. (b) French angelfish. Courtesy of Reese/OAR/ National© Undersea Jones Resear &ch PrBartlettogram (NURP). Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION are adapted for withstanding the crushing ductive areas of the ocean are near the shore, water pressures found in the deep sea. where upwelling brings the nutrients from the The photic zone is the upper part of the sea bottom into the photic zone and where nu- © Jones &biome Bartlett where Learning, light penetrates. LLC The depth of ©trients Jones in the & oceanBartlett flow Learning, in from land. LLC this zone depends on the clarity of the water— Estuaries are transitional ecosystems be- NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION as shallow as 5 m or as deep as 100 m in tropi- tween the ocean and freshwater biome. Estu- cal waters. The photic zone is the main zone of aries, such as the Chesapeake Bay of Maryland photosynthesis and therefore is crucial to life and Virginia, occur where rivers and streams in the biome. The photosynthesizing plants, flow into the ocean Figur( e 4-22). Five major which form the base© of Jones the marine & Bartlett food pyra Learning,- rivers LLC and over 100 smaller tributaries© Jones from & Bartlett Learning, LLC mid, are mainly tinyNOT planktonic FOR organismsSALE OR in DISTRIBUTION- six states flow into the ChesapeakeNOT FORBay. ThisSALE OR DISTRIBUTION cluding diatoms. produces wide fluctuations in the salinity of Although the marine biome covers nearly these waters to which organisms must adapt. three-fourths of the Earth’s surface, most of the On the other hand, the flowing rivers provide open© ocean Jones supports & Bartlett relatively Learning, little life. LLCMuch a rich supply of© nutrientsJones & that Bartlett are rarely Learning, ri- LLC of the ocean is too deep for light to penetrate valed anywhere else on Earth. An estuary’s NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION and drive the photosynthetic food base. The shallow water means tides and waves keep deep ocean is poorly oxygenated, which also large amounts of nutrients suspended in the restricts the ability of species to live there. The water along with oxygen, and light is avail- creatures in the deep ocean are largely depen- able for increased photosynthetic activity. As © Jones &dent Bartlett on the Learning,dead organic LLC material that drifts ©a result,Jones estuaries & Bartlett can Learning, support large LLC popu- NOT FORdown SALE from OR above DISTRIBUTION for food. The most pro- NOTlations FOR of organisms.SALE OR TypicalDISTRIBUTION animals that 4.3 Biomes and Communities 125 2nd pAGES © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION.

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR reduceSALE flooding OR DISTRIBUTION impacts and water pollution by absorbing water. They are also critical habitat for many animal species including numerous highly endangered wetland species. Riparian plants are also important for © Jones & Bartlett Learning, LLC aquatic life: they help© Jones protect &the Bartlett water from Learning, LLC NOT FOR SALE OR DISTRIBUTIONdirect sunlight andNOT reduce FOR heat SALE stress OR and DISTRIBUTION provide many nutrients for aquatic life in the form of leaves and other detritus. The slower motion of water in lakes and © Jones & Bartlett Learning, LLC ponds© Jonesleads to & stratification Bartlett Learning, of the water: LLC the NOT FOR SALE OR DISTRIBUTION uppermostNOT FOR layer SALE of water OR has DISTRIBUTION plenty of oxygen while the oxygen decreases with depth. The uppermost layer is also much warmer during the summer and cooler during the winter than the lower layers. There is a sharp © Jones & Bartlett Learning, LLC © Jones &boundary, Bartlett the Learning, thermocline LLC, between the warm NOT FOR SALE OR DISTRIBUTION NOT FOR surfaceSALE waterOR DISTRIBUTION and the colder deeper waters. Summertime swimmers often notice this abrupt transition to cold water when diving. Most of the mixing between the uppermost FIGURE 4-22 A satellite image of Chesapeake Bay. Courtesy of Jacques and deeper layers occurs during seasonal Descloitres, MODIS© Jones Land Science & Team/NASA. Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTIONchanges known as NOTspring FOR and SALEfall overturn. OR DISTRIBUTION As with rivers and streams, lakes also have a live in estuaries include oysters, which form transitional zone with land, sometimes called reefs that support many other species, such the shore zone. It functions in the same way as the riparian zone, reducing flooding and © Jonesas sponges& Bartlett and Learning,barnacles that LLC attach to the © Jones & Bartlett Learning, LLC reef. The reef traps nutrients, and this attracts heat stress and providing nutrients and critical NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION many fish and other species. A single oyster habitat for many wetland and aquatic species. reef has been found to support more than As in the ocean, freshwater has two basic 300 species of organisms. life zones: the bottom-dwelling benthic organisms and the swimming pelagic creatures (Fig- Freshwater Biome © Jones & Bartlett Learning, LLC © Jones &ur Bartlette 4-23). Familiar Learning, benthic LLC organisms include Liquid freshwater covers only 2% of the NOT FOR SALE OR DISTRIBUTION NOT FOR freshwaterSALE OR mussels DISTRIBUTION that filter nutrients from Earth. The freshwater biome includes both the water and a variety of insects and other running waters, such as rivers and streams, crawling or burrowing invertebrates such as and standing waters, such as lakes and ponds. In general, rivers and lakes are larger and more© Jonespermanent & Bartlett than Learning,streams and LLC © Jones & Bartlett Learning, LLC ponds. TheNOT faster FOR motion SALE of OR running DISTRIBUTION waters NOT FOR SALE OR DISTRIBUTION tends to keep them more highly oxygenated and easier to clean up after being polluted. A river or stream is an open ecosystem in that it © Jonesderives & Bartlett most of Learning,its organic materialLLC from up- © Jones & Bartlett Learning, LLC stream or runoff from the land. Many species NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION feed on this detritus. Of special ecological importance is the riparian zone. This is the area along the river or stream bank, consist- ing of cattails, reeds, willows, river birches, © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC and other plants that tolerate high moisture. FIGURE 4-23 Beavers are highly dependent on water and can be NOT FOR SALE ORThese DISTRIBUTION plants are very important buffersNOT that FOR consiSALEdered pelagi ORc m ammals.DISTRIBUTION © Photodisc. 126 Chapter 4 The Distribution of Life on Earth 2nd pAGES © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION.

FIGURE 4-24 Red-eared sliders prefer freshwater habitat with slow-moving water, mud bottoms, and a nice log or other handy place for basking in the sun. © Elena Kouptsova-Vasic/ShutterStock, Inc.

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC crayfish. Fish, of course,NOT FORare the SALE most ORfamil DISTRIBUTION- waterlogged or submerged. BecauseNOT the FOR anaer SALE- OR DISTRIBUTION iar swimming organisms, ranging from catfish obic conditions slow organic decomposition, that prefer bottom waters to perch and trout wetlands accumulate rich layers of organic that prefer shallower depths. Amphibians are material. Reeds and grasses dominate marshes, abundant in many freshwaters because they whereas trees dominate swamps. Wetlands © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC require water to reproduce. Other vertebrates support a high diversity of organisms and carry includeNOT turtles FOR and SALE a few OR water-adapted DISTRIBUTION mam- out important functionsNOT FOR for SALE the biosphere OR DISTRIBUTION de- mals, such as otters, beavers, and muskrats. spite the small land area they occupy on Earth. Algae are usually an especially important type For example, wetlands help filter out pollut- of plant in freshwater ecosystems, although ants, replenish groundwater supplies, and pro- © Jones &water Bartlett lilies, variousLearning, “grasses,” LLC and other plants ©vide Jones natural & floodBartlett control. Learning, (Saltwater LLC marshes NOT FORoccur SALE as well.OR DISTRIBUTION NOThelp protect FOR SALEagainst OR storm DISTRIBUTION surges.) Wetlands Marshes and swamps are classified as are home to a staggering number of bird, am- wetlands. The ground in these ecosystems are phibian, insect, and reptile species (Figure 4-24).

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 4.3 Biomes and Communities 127 2nd pAGES © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION.

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FORCas SALEe ORConservation DISTRIBUTION and theNOT FOR SALE OR DISTRIBUTION Study Geography of People 4-3 © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION e see in this chapter how species are not are set aside to protect species. Are these nature randomly distributed on Earth. As you preserves geographically selected so that they pro- Visit Wmight suspect, people are not randomly tect areas of high species diversity? An article by distributed either. Far more people live in some J. Michael Scott and colleagues (2001) published in www.environment.jbpub.com© Jonesareas, & suchBartlett as near Learning, coastlines, thanLLC in other areas, the journal© Jones Ecological & Bartlett Applications Learning, examined LLC the for more information NOT FORsuch asSALE deserts. OR Do DISTRIBUTION you suppose that large con- distributionNOT FOR of more SALE than 2,500OR DISTRIBUTION protected areas in centrations of people tend to occupy the same the lower 48 states of the United States. They found areas that are favorable for high species diversity that less than 6% of the total area is protected and density? If true, this has enormous implica- and that the reserves were disproportionately lo- tions for conservation. cated in areas of higher elevations and poor soils. © Jones & Bartlett Learning,This hypothesis LLC seems likely at first© glance. Jones &This Bartlett pattern Learning,occurs because LLC land that is set aside NOT FOR SALE ORWe DISTRIBUTION have seen, for example, that biomes suchNOT as FOR forSALE preserves OR DISTRIBUTIONhistorically has been mountainous the desert and tundra have a low productivity. land that was not productive for agriculture and This not only lowers the species diversity and was of little economic value. As you might sus- density of these areas, but it also makes them pect, this is bad for the preservation of biodiver- less favorable places for agriculture. In addition, sity because many areas of high species diversity, many people© Jones prefer to& Bartlettavoid the Learning,cold climate ofLLC such as wetland and ©riparian Jones habitats, & Bartlett occur onlyLearning, LLC the tundraNOT or the FOR heat SALEof the desert; OR DISTRIBUTION however, this at low elevations. A moreNOT effective FOR SALE reserve ORsystem DISTRIBUTION is only a hypothesis based on the initial evidence must add land that is more representative of all presented in this chapter. What does more de- habitats, even if it requires setting aside land that tailed evidence indicate? is desirable for agriculture and other human uses. An article that Andrew Balmford and col- © Jonesleagues & Bartlett (2001) published Learning, in the journalLLC Science ana- References© Jones & Bartlett Learning, LLC lyzed a map of sub-Saharan Africa at a very high NOT FOR SALE OR DISTRIBUTION 1.NOT Balmford FOR A, MooreSALE J, BrooksOR DISTRIBUTION T, Burgess N, Hansen degree of resolution. They compared the number L, Williams P, Rahbek C. Conservation conflicts across of bird, mammal, snake, and amphibian species Africa. Science 2001;291:2616–2619. in each square on a grid with the human popu- 2. Scott JM, Davis FW, McGhie G, Wright R, Groves C, lation density of that square. They found that, Estes J. Nature reserves: Do they capture the full range © Jones & Bartlett atLearning, least for most LLC of Africa, the scenario ©seems, Jones & Bartlettof America’s Learning, biological diversity?LLC Ecological Applica- tions 2001;11:999–1007. NOT FOR SALE ORunfortunately DISTRIBUTION for most nonhuman species,NOT to be FOR SALE OR DISTRIBUTION true. People do tend to occupy the same areas that Questions are richest in species diversity. This is not entirely because of plant productivity. Other reasons are 1. Name two state parks in your state. Do you that people prefer to live in areas of fertile soils, at know anything about their history or why low elevations,© Jones and near & Bartlett water bodies. Learning, All of these LLC they were located© whereJones they & are?Bartlett Learning, LLC geographicNOT factors FOR also SALE tend to OR support DISTRIBUTION relatively 2. California has theNOT highest FOR population SALE OR of any DISTRIBUTION high numbers of species. state and also the most native plant species. Another important aspect of species geogra- What reasons can you give for its high rank phy is how it relates to the nature reserves that for both population and biodiversity? © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

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© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FORn SALE study OR DISTRIBUTION guide NOT FOR SALE OR DISTRIBUTION Summary • Primitive bacteria arose at least 3.5 billion • Climate, especially temperature and rainfall, years ago. largely determine biomes. • New species originate© Jones through & naturalBartlett selec Learning,- • The LLC seven terrestrial biomes are© Jonestropical &for Bartlett- Learning, LLC tion, which passes NOTon beneficial FOR SALE genes. OR DISTRIBUTIONests, savanna, grasslands, deserts,NOT temperateFOR SALE OR DISTRIBUTION • Biodiversity is often measured as number of forests, taiga, and tundra. species. • The two aquatic biomes are marine and fresh- • Rain forest sampling, ecological ratios, and water. species area curves estimate biodiversity. • Biomes© Jones are suites & Bartlett of communities Learning, that LLCshare © Jones & Bartlett Learning, LLC manyNOT basic FOR adaptations. SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Key Terms © Jones &amino Bartlett acids Learning, LLC eukaryotes © Jones & Bartlettshore zone Learning, LLC NOT FORbenthic SALE OR DISTRIBUTION explosion of life NOT FOR SALEspecies OR DISTRIBUTION biodiversity genes species area curve biome mutation species richness Cambrian explosion natural selection taxonomists chaparral pelagic taxonomy DNA © Jones & Bartlettphotic zone Learning, LLC thermocline © Jones & Bartlett Learning, LLC economic value NOT FOR SALEprotocells OR DISTRIBUTION wetlands NOT FOR SALE OR DISTRIBUTION estuaries riparian zone xerophytes

St©ud Jonesy Que & Bartlettstion Learning,s LLC © Jones & Bartlett Learning, LLC 1. NOTWhat FORare amino SALE acids OR and DISTRIBUTION what is the sig- 9. Explain whyNOT tropical FOR rain SALE forests OR have DISTRIBUTION such nificance of the amino acid experiments of high biodiversity. Miller and Urey and later Fox? 10. Do tropical rain forests have fertile soils? 2. Describe the process of evolution by natu- Why or why not? ral selection. How has the physical environ- 11. Describe four adaptations that plants can © Jones & Bartlettment affected Learning, the history LLC of life? © Joneshave for& Bartlettsurvival in Learning,the desert. LLC NOT FOR SALE3. If a populationOR DISTRIBUTION consisted of a small number NOT 12. How FOR are SALE the ORtwo DISTRIBUTIONfundamental aquatic of individuals, what effect might natural se- biomes recognized? lection have on its survival? 13. Describe why riparian zones are so important. 4. Describe how Mendel’s discovery helped in 14. What is the sharp boundary between warm the understanding of variation. and cold lake waters? © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC 5. Explain two basic causes of variation. 15. Explain why much of the ocean can be con- 6. Approximately howNOT many FOR genes SALE do humans OR DISTRIBUTION sidered a “biological desert.”NOT FOR SALE OR DISTRIBUTION have? Why is this number significant? 16. Name the major biomes of Earth. Which 7. What factors may have caused the “explo- biome or biomes do you live in? Would you sion of life”? consider it one of the more favorable biomes 8. Define biodiversity. Is there only one way to for human habitation? Why or why not? ©define Jones this & concept? Bartlett HowLearning, can biodiversity LLC © Jones & Bartlett Learning, LLC NOTbe measured FOR SALE or estimated? OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

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© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE ORWha DISTRIBUTIONt’s the Evidence?NOT FOR SALE OR DISTRIBUTION 1. The authors state that new species may arise 2. The authors state that the number of species as a result of natural selection of individual on Earth could be anywhere from 5 to 100 variation and the isolation of populations. million species. What is the evidence given What evidence is given to support this? Can to support this estimate? you© think Jones of evidence& Bartlett for otherLearning, causes LLCof © Jones & Bartlett Learning, LLC evolution?NOT FOR If so, listSALE them. OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Calculations © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC 1. If taxonomists have described approximately 2. If taxonomists have described approxi- NOT FOR 1.8SALE million OR different DISTRIBUTION species and 56% of these NOTmately FOR 1.8 millionSALE speciesOR DISTRIBUTION but there are ac- are insects, how many of the described species tually 30 million different species on Earth, are insects? what percentage of the species have taxonomists described? © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE ORIllu DISTRIBUTIONstration ReviewNOT FOR SALE OR DISTRIBUTION 1. Using Figure 4-8, explain how there can be 2. In which biomes would you expect to find a polar climate at the equator. the type of diversity shown in Figure 4-4a?

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