Abiotic and Biotic Factors of the Environment

UNIT 2 NOTES

ABIOTIC AND BIOTIC FACTORS OF THE ENVIRONMENT

I. Abiotic and Biotic

 Abiotic factors of the environment are nonliving factors, such as temperature, precipitation, rock bed, salinity, sunlight etc.

 Biotic factors of the environment are living factors, such as predators, food sources, interspecific and intraspecific competition, parasite, disease causing agents

II. Climate

 Climate – the long-term prevailing weather conditions in a particular area, we are talking about long time periods

 Weather – includes temperature, precipitation, cloud conditions, light conditions at a given time

 Climate is determined by a wide range of factors:

i. Sun light and heat that it generates

ii. Atmosphere composition

iii. Surface conditions

iv. Pressure

v. Wind

 Because the Earth is a sphere, regions around the equator receive sunlight at a 90° angle, while the areas on the South and North receive the light at a lower angle. This lower angle reduces the energy that reaches these locations

 Seasons are due to the tilted angle of the Earth’s rotational axis around the sun.

 Ocean currents and wind patterns also influence temperature and precipitation all around the world.

 Climate is also affected by topography. As moisture filled air moves up on high mountains, it cools down and forms droplets of water that fall as rain. However, as the air moves down the mountain, it does not bring any more moisture. So the downwind side of mountains is dry. III. Climate and Human Influence

 Climate change is any change in global temperature and precipitation patterns. Earth naturally has fluctuations in these patterns over very long time periods, hundreds of thousands to millions of years.

 Anthropogenic climate change – alterations in long-term atmospheric conditions cause by human activity. Evidence suggests that today’s climate change is so fast, it cannot be caused by natural conditions alone. It is mostly due to human activities.

 Greenhouse gases play a major role in determining the earth’s climate. These are compounds in the atmosphere that absorb heat that radiates from the earth’s surface and reradiate it back to the surface – greenhouse effect

 Greenhouse gases include water vapor, CO2, CH4, NO, and some other products like chlorofluorocarbons. Human activities, such as burning fossil fuels, industrial activities and agriculture increased the concentration of these gases in the atmosphere. Figure 4 and Figure 5 in Module 178.

 Bioskill – Interpreting Graphical Data of Atmospheric CO2 Concentrations – Figures 6, 7 and 8 in Module 178

 Consequences of the climate change:

i. Glaciers and sea ice shrink

ii. Snow and sea ice melts earlier each year

iii. Decreased reflection of the white snow and ice cover decreases solar radiation which increases temperature even more – positive feedback mechanism – accelerating mechanism in which the consequences push a mechanisms to go even faster

iv. Increased surface temperatures

v. Changes in weather patterns and precipitation

vi. Permafrost melts and releases more greenhouse gases – yet another positive feedback

vii. Increased precipitation may increase erosion in some areas

Figure 9 – Module 178

IV. Terrestrial Biomes  Biome – a large geographical area that contains a unique collection of naturally occurring animals and plants. Biomes are categorized as aquatic and land biomes.

You need to understand how climate and other factors influence biomes and how their biodiversity can be useful for us.

 Main environmental factors that determine the nature of a biome are average yearly temperature (°C) and the annual precipitation (cm). These are the most important abiotic factors of terrestrial biomes.

 Forest biomes usually require substantially more yearly precipitation than grassland biomes.

 Higher annual temperatures with lower precipitation can lead to deserts, while very low temperatures result in tundras.

 Climatographs are used to show the temperature and precipitation in a given are broken down by month.

 Major human activities such as deforestation, overwatering and habitat destruction endangers terrestrial biomes.

V. Aquatic Biomes

 Aquatic biomes are divided into two major types: freshwater and marine biomes.

 They make up about 3/4th of the earth’s surface.

 They are interconnected with the terrestrial biomes because of the water cycle.

 Most important abiotic factors in aquatic biomes:

o Salinity – salt content (fresh water, brackish water, salt water, brine)

o Nutrient content (oligotrophic water, eutrophic water)

o Light intensity (photic and aphotic zones)

o Temperature stratification (thermocline)

o Bottom surface (benthic zone) Figure 4 – Module 179 as an introduction to the case study.

As a conclusion of the case study:

Many abiotic factors can interact to cause various changes in the environment. For example, oxygen concentration can be depleted in aquatic biomes by warming water, increased number of decomposers that use up the oxygen, increased salinity, less turbulence and too high nutrient concentration.

Eutrophication – a dangerous condition in both fresh water and marine biomes. Because of increased nutrient wash off from farms and possibly sewage from cities, aquatic biomes become eutrophic. Algae and bacteria can reproduce at a higher pace by using the nutrients from the wash off. The consequences:

 Higher number of heterotroph bacteria use up the oxygen in the water

 Algae and bacteria cover the surface of the water so photosynthetic organisms in the water don’t get sunlight and die

 Toxins are produced by certain algae and bacteria that can harm other living organisms in the water

 Higher number of dead organisms increase the number of decomposing organisms and they also use up the oxygen in the water

POPULATIONS

I. Human Population Growth

 Populations can increase their numbers by the following:

o Increasing birth rate

o Decreasing death rate o Increasing immigration and/or decreasing emigration

 Due to better healthcare, humans live longer today than ever before in human history. As a consequence, human population exploded since the nineteenth century.

Data analysis – 7 Billion and Counting, Nature

http://www.pbs.org/wgbh/nova/worldbalance/numb-nf.html -- human populations over time

II. Estimating Populations:

 Population ecology studies the number, composition, growth rate, dispersion and environmental factors of populations.

 Populations: all living organisms that belong to the same species and live in the same area.

 The number of organisms in a population can be estimated or calculated by using:

o Density – number of organisms per unit area or per volume. Fairly constant density over time is an indication of a healthy population.

o Dispersion – The changes of density of a population across its range. Can be clumped (herds of grazing animals or schools of fish grouping around a food source), uniform (creosote bushes in the desert because of the limited water supply, artificially planted farm trees in an orchard), random (usually for no particular reason, birds flying in the wind or insects flying, weeds as their seeds were dispersed)

o Demography – calculations to account for the birth, death rate and immigration and emigration data. Life tables or survivorship curves are used to describe the demography of populations. Survivorship curves show how mortality varies with age of the individuals in a population. Type I survivorship – organisms rarely die when young, parents take care of their young and organisms tend to die in large numbers when old. Type II survivorship – organisms have an equal chance of dying when young or old. Type III survivorship – organisms die in an early age but the ones that survive, can live for a long time.

Figure 3 and Table 3 in 182 III. Growth of Populations Over Time

 Death, birth, immigration and emigration changes population numbers.

 The number of organisms in a population will be limited by various environmental factors, such as food, nesting place, water supply etc. The maximum number of individuals an environment can support over time is called its carrying capacity (K).

 Exponential growth is where the growth rate increases exponentially. This is due to having plenty of resources available for all new organisms. How many new organisms are added into the population by each already present organism in a given time period

is called the per capita increase (rmax), this multiplied by the population size (N), gives us

the population growth or decline over time (G). G = r(max) N (G can also be represented by dN/dt)

 Logistic growth is when the resources start to limit the growth of the population because the carrying capacity of the environment is reached by the individuals in the

population. As the population size (N) gets larger, the per capita increase (rmax ) gets

smaller, because fewer offspring are born or can survive. In this case, G=rmax N (K-N/K)

(G can also be represented by dN/dt) In this case, r = rmax (K-N/K)

IV. K and r Selection

 Evolution of populations developed different ways of dealing with the varying carrying capacity of the environment.

 K selection is a process in which organisms produce fewer offspring, later in their lives because the environment cannot support many new offspring. These organisms care for their young.

 r selection is a process in which organisms produce lots of offspring, reproduce fast, from a young age but do not care for their young. These organisms have a different strategy to assure reproductive success.

Think back to evolutionary fitness. The goal is to reproduce

V. Factors that Regulate Population Size

 Once the carrying capacity of the population is reached, various environmental factors will limit the number of organisms in the population – density-dependent factors affect the population only at certain densities. Examples of these are food sources, water sources, nesting place, spread of disease causing agents, etc.  Density-independent factors impact the population regardless of its density. Examples: weather conditions, volcanic eruption etc.

 Because these conditions change over time and the carrying capacity of the environment can change with it, population numbers fluctuate greatly over time.

Figures 8 and 9 Module 181

http://www.pbs.org/wgbh/nova/earth/global-population-growth.html

http://www.youtube.com/watch?v=sc4HxPxNrZ0 – 7 billion

Figures 19 and 21 in Module 181

VI. Evolution of Life History Strategies

 Each species confronts a trade-off between parental investment and the number of offspring it produces. Some species may have only a few offspring and takes good care of them (great investment), while others may have many offspring but invest little energy into taking care of them. Each strategy has its advantages and drawbacks.

 Most species has a life history strategy that is in between the two extremes.

Complete the case study on Population Dynamics and the concept map COMMUNITIES – SPECIES INTERACTIONS

I. Introduction

 Communities – all living organisms in a given area that interact with each other. This interaction can be two basic types:

i. Intraspecific interaction – the interacting organisms belong to the same species

ii. Interspecific interaction – the interacting organisms belong to different species

 Ecological Niche – Every species has a determined set of behaviors, resources and environmental factors that they can tolerate. Fundamental niche describes all limiting factors and resources that a species can possibly utilize. Realized niche describes all factors that it does utilize in the presence of biotic interactions with competitors and predators.

II. Interspecific Interactions

 There is a wide range of interactions between species. The following list shows the most common types (+ means beneficial interaction, - means harmful interaction, 0 means neutral or no interaction):

i. Competition (-,-) because it is harmful for both parties, competition limits the number of individuals in each population and also drives evolutionary fitness because the organisms of the two parties compete with each other for resources. (Ex. Plants competing with other plants for sunlight in a forest, zebras and antelopes compete for grass on the savannah). Figure 2 – Module 185. Competitive exclusion principle states that in a community, where two species compete for the same limiting factors, they cannot coexist and only one species will survive. If two species compete with each other for the same resources, they may be forced to divide up the available resources with each other – resource partitioning. In this case, evolution may benefit organisms that have more different traits from the competition.

ii. Predation, herbivory, parasitism (+,-) – feeding relationships, where one organism benefits by consuming the other organism or its parts. However, these relationships can also be beneficial for the entire ecosystem, when for example herbivores are controlled by predators, so plants can survive. Coevolution of both parties is also very powerful. List some adaptations below of each party:

Adaptations of Adaptations of Adaptations of Adaptations of Adaptations of Adaptations of predators prey plants herbivores parasites hosts Enhancement Forming packs, Toxins, thorns, Behavioral – Immune of senses, playing dead, unpleasant Modified parasitic response agility, sharp warning signals taste, fast digestive wasps, social against the teeth, claws, (behavioral growth, system, strong parasitism – parasite, acids strong adaptations), teeth, tough cuckoos, and digestive muscles, bones cryptic lips, long legs Structural— enzymes coloration and necks to resistance to against (camouflage), reach trees, stomach acid parasites in the warning resistance to and enzymes digestive coloration, toxins by forming system toxins, thick outer unpleasant covering, taste, Fast Mimicry reproduction (Batesian – harmless copies harmful, Mullerian— harmful and harmful look similar)

The following relationships are all considered symbiotic relationships – a relationship between two species that live in intimate contact.

iii. Amensalism (-,0) occurs, when one species inadvertently harms another. Usually occurs when a metabolic waste is secreted by one organism that is harmful for another (break mold secretes penicillin, that harms bacteria but does not directly benefit the bread mold either)

iv. Mutualism (+,+) Sometimes mutualistic relationships are obligate, neither party can survive without the other, but sometimes facultative, they can survive without each other but they are both better off with each other. (Termites and wood digesting protists in their digestive system – obligate, clownfish and sea anemones – facultative).

v. Commensalism (+/0) Includes organisms that use another one for transportation (mites sitting on a beetle)

III. Dominant and Keystone Species

 Dominant species have a disproportionately larger influence on the community because of their large biomass in that particular community. (Ex. Kelp in kelp forests because although there are other algae, kelp is the most common there. Dominant grass species in the savannah.)

 Keystone species – Species that may not have the largest biomass in the community, but they influence the community food chains or webs more than others. (Ex. Starfish in coastal areas are influential because they keep mussel numbers under control. Sea otters in kelp forests are influential because they keep the sea urchin populations under control that otherwise would destroy the kelp.)

Please review food chains and food webs. We don’t spend any time on it in class.

IV. Disturbance and Succession

 Disturbance is a discrete event in time that causes stress and mortality or both to at least some species in the community and results in change in the community. Ex. Fires, hurricanes, human activities such as clearing a land for farming.

 Ecosystems tend to follow predictable and directional change in species composition and environmental factors. Immediately after the disturbance, the community is dominated by species that are rapid colonizers and grow very fast, but are less successful at competitions for nutrients and light. Later on these species are outcompeted by slower growing but more dominant species and finally a climax community is reached – today it is considered the most diverse community that can potentially exist in a given area.

 Primary succession – occurs on habitats that had been unavailable for life previously, so they don’t have soil for plants to grow on. These communities start with bacteria, lichens, mosses.

 Secondary succession – occurs on land that was previously cleared of most species. Because soil exists on these, weeds, flowering plants that are fast growing can take root very quickly.

Do Figures 4 and 5 activites

ECOSYSTEMS – ENERGY

I. Laws of Thermodynamics That Guides Energy Transfer in Ecosystems

 Ecosystem – group of organisms and all of their abiotic surroundings in a given area.

 The first law of thermodynamics – energy can change from one form to another but cannot be created or destroyed.

 The second law of thermodynamics – energy transfers are never 100% efficient, so some of the energy is always lost as heat and not usable for living organisms any more. For example, only 0.1% of energy from the sun that hits the earth is used by autotrophs for photosynthesis.

 Free energy – a term that we use to describe all available energy sources for living organisms. II. Energy Flow in Ecosystems

 Energy always flows through the ecosystem and does not get recycled back into it.

 Energy enters food chains and webs through photosynthesis by producers. They convert the light energy of sunlight into chemical energy. This energy is used by all other organisms in a given area.

 Special graphs called pyramids are used to depict the transfer of energy and matter within a given food chain. Types of pyramids:

i. Energy pyramid – shows the energy content of each trophic level in an ecosystem. The unit can vary but usually includes energy and an area component, sometimes even a time component.

ii. Pyramid of biomass – shows the energy content on each trophic level but in mass unit, as the energy content of organic matter. iii. Pyramid of numbers – shows the number of organisms on each trophic level. Less informative from the energy standpoint, because a large tree can support several different primary consumers.

Figure 3 activity in Module 190

 The first two pyramids clearly show major losses of energy and biomass on each trophic level. The reason for this is the second law of thermodynamics. The energy is lost as heat during the various chemical reactions on each trophic level to build the actual organism and perform its life processes. Very little energy is actually passed from one trophic level to the next. Some of the energy that is lost as waste matter can be used by decomposers but lots of it is lost as heat and cellular respiration.

 The flow of energy can also vary depending on various limiting factors. See later

III. Invasive Species and Their Influence On Energy Flow

 Invasive species – species that are moved into new ecosystems usually by humans, intentionally or unintentionally. Most of these species die out because they are not adapted to live in the new environment. However, some become so successful that they threaten the native species because they don’t have natural predators/herbivores or competition in the new ecosystem. Examples: kudzu, Asian carp, Burmese python etc.

 Invasive species can shift the energy flow in the new ecosystem, because they pass less energy up on the trophic levels. They usually don’t have natural predators or herbivores, so they can spread and only decomposers can get the energy from them. IV. Limits of Primary Production

 Ultimately the base of an energy pyramid determines the available energy source for all organisms in a given ecosystem. Photosynthesis is the main process that takes in the energy.

 Primary production – the mass or energy of biomass that is produced by the producers in a given area at a given time period.

o Gross primary production (GPP) – refers to the total mass or energy of biomass that plants produce by photosynthesis

o Net primary production (NPP) – refers to the mass or energy of biomass that is available for the next trophic level after cellular respiration.

NPP = GPP – CR

Measuring Biomass Using Satellite Imagery Figure 6, Module 190

 Some nutrients such as nitrogen and phosphorous limits primary production because they tend to run out of the soil the fastest. Farmers use fertilizers to replace these nutrients if they are depleted in the soil.

 However, fertilizers can wash into lakes and rivers and make them eutrophic – eutrophication.

Review notes on Gulf of Mexico Case Study

 Primary production in terrestrial ecosystems is also increased with increasing temperature and precipitation. – Explain why.

V. Energy Transfer Among Trophic Levels

 Consumers already take in substantially less energy than plants produce by gross primary production. Than on each consumer level, substantial energy is lost for cellular respiration and as waste.

Figures 11 and 12 – Module 190

 Production efficiency – the efficiency with which a consumer creates biomass using the energy from its food

 Trophic efficiency – a measure of the percentage of production at any trophic level compared to the production at lower trophic levels. Basically this is the mass or energy of biomass that is passed on from one trophic level to the next. ECOSYSTEMS – MATTER

 Cycling of Materials:

 While energy flows through the ecosystem, matter always gets recycled back into it. When complex organic molecules are broken down by decomposers, the atoms of those molecules are released back into the environment than can be used again by producers.

 The Law of Conservation of Mass – states that matter cannot be created or destroyed only changed into new forms.

 The earth is basically considered a closed system when it comes to matter recycling. Some matter escapes the atmosphere and some matter comes to the earth by meteors, but for the most part the matter is the same as it has been for millions of years.

 Biogeochemical cycles are changes in the form of elements. Bio refers to the appearance in living organisms or organic matter, geo refers to the appearance of matter in rocks and minerals, chemical refers to the appearance of matter in other chemical forms.

 The Water Cycle

 All chemical reactions in living organisms take place in aqueous solutions so all living organisms need water.

 Most of the water on the planet is salt water and only usable for marine organisms. The fresh water can also be unavailable, because it is in frozen forms in arctic ice or glaciers.

 Main storage areas that are available for living organisms are: water vapor in the atmosphere, lakes, rivers and ground water trapped underground.

 All living organisms are able to take in water once it falls as precipitation from the atmosphere.

 The excess water can run off of surfaces, evaporate back into the atmosphere or is stores in aquifers.  The Carbon Cycle

 Every organic compound contains carbon, so the carbon cycle is required to build all of our molecules.

2-  Main reservoirs of carbon are CO2 in the atmosphere, in rocks as CO3 ions, in the oceans as

dissolved CO2, in fossil fuel reserves as unavailable sources until we burn those and turn them

into CO2 again.

 Producers such as algae, plants and some bacteria are able to trap CO2 from the atmosphere or from the ocean by photosynthesis and convert it to organic matter during assimilation. Once the organic matter is formed, carbon can move up in the trophic levels to the consumers and

decomposers. Producers, consumers and decomposers all return carbon to CO2 during cellular respiration. The rest of the organic matter is broken down by decomposers and also returned to

 Carbon reserves in rocks are only available after weathering of rocks so they can be trapped for a long period of time.

 Organic matter that did not decompose can turn into fossils by fossilization or to fossil fuels over a long period of time. However, once fossil fuels are burned, they are released again into the

atmosphere as CO2.

VI. The Nitrogen Cycle

 Nitrogen is required for all living organisms to build their proteins and nucleic acids.

 Major reservoir of nitrogen is in the atmosphere where it is found as N2 78% of the atmosphere.

However, N2 is very hard to break down because of its triple bond.

+  Nitrogen fixation – N2 is converted into NH4 by nitrogen fixing bacteria. Some of these bacteria live in the soil, others live in the root nodules of legume plants (such as beans, peas and lentils). Once it is in ammonium form, nitrogen is available for other bacteria to use it.

+ - -  Nitrification – is a process that converts NH4 to NO2 or NO3 (nitrite and nitrate) done by nitrifying bacteria that mostly live in the soil.

 Assimilation – Once the nitrogen is in a water soluble nitrite and nitrate form, plants and other autotrophs are able to take it in and convert it to organic matter such as proteins and nucleic acids. Some plants are also able to take in ammonia and assimilate that into their organic matter. This conversion process is called assimilation.

 Animals take in organic matter from plants and build their proteins and nucleic acids.

 Decomposition(ammonification) – breaks down proteins, nucleic acids and their monomers into + ammonium (NH4 ) and returns it into the soil. Decomposers also include many bacteria, fungi and some other organisms.

-  Denitrification – converts nitrates (NO3 ) to nitrogen gas (N2). This process is done by denitrifying bacteria. These bacteria generally live under anaerobic conditions in water, like swamps. VII. The Phosphorous Cycle

 Main reservoir of phosphorous is in the lithosphere, in the form of phosphate in rocks.

 Weathering of rocks and erosion release these phosphates into water soluble forms. Mining and fertilizers containing phosphorous are also used.

 The water soluble form of phosphorous can be taken in by plants and used to synthesize organic matter such as nucleic acids, nucleotides (like ATP, NAD, NADP, FAD etc.) and phospholipids.

 Dead organisms and waste than decomposed by decomposers and the phosphorous is released back into the soil. However, water soluble phosphate usually washes out of the soil into lakes, rivers etc. and is used in aquatic ecosystems. Dead organisms can also settle on the bottom of rivers, lakes and can became compacted to form new rocks.

 The release of phosphorous again can take for a long time, so this cycle is a lot slower than the others.

Both nitrogen and phosphorous runoff into waterways contribute to eutrophication – here we go again.

Role of decomposition in the biogeochemical cycles – figures 15 and 16.

THE BIODIVERSITY ISSUES

I. How Did Humans Alter the Biogeochemical Cycles?

 Alteration of the carbon cycle by humans o consumption or deforestation of plants decreased NPP on terrestrial biomes by about 40%

o burning fossil fuels increased CO2 concentrations in the atmosphere – global climate change

o increased CO2 concentration in the oceans decreases the pH of ocean water

 Alteration of the nitrogen cycle by humans

o Increased available nitrogen changed soil chemistry that reduced biodiversity

o Cultural eutrophication

 Alteration of the atmospheric oxygen-ozone cycle

o The protective ozone layer is depleted by human made chemicals like CFC’s, which decreases the UV protection of the planet Figure 8 – 192

 Toxin release by humans

o Results in biomagnification (bioaccumulation) – the buildup of toxins in the tissues of organisms, mostly on the higher trophic levels

 Habitat degradation

o Habitat destruction is the complete removal of a habitat by human activities

o Habitat degradation is the decrease of the quality of a habitat due to human activities, such as pollution, overfishing, selective deforestation, fragmenting the habitat etc.

II. BIODIVERSITY ISSUES

In groups of 3-4 you will use various sources to discuss and answer the following questions:

1. What is biodiversity? Besides the definition, find out how many different species of organisms we estimate lives on the planet today.

2. Explain why biodiversity is important for (use specific examples)

a. Ecosystem stability

b. For humans

c. For planetary concerns 3. What is extinction? Name some major reasons for extinctions of specific species. Describe the consequences of one specific extinction event.

4. Describe three government actions, organizations or laws that helped to slow the extinction rate on the planet.

ANIMAL BEHAVIOR

I. Behavior As An Adaptation For Survival

 Behavior – actions to address particular stimuli for their survival and reproduction

 Behaviors can influence a species’ response to external environmental stimuli to obtain food, avoid predators, find mates, raise the young etc. These behaviors influence the evolutionary fitness of organisms.

 Fixed action patterns – an innate response that directly results from the detection of a sign stimulus. This type of response does not require any previous experience to learn and once the specific action is triggered, it will be completed even if the sign stimulus disappears. (Ex. Gulls roll their eggs back to the nest, gulls also regurgitate food when a red dot on their beaks is pecked by chicks, sticklebacks attack any red-colored object or organism that enters their territory etc.)

 Learned behaviors -- Many types of behaviors are very complex and are triggered by a combination of environmental factors and ingrained signals not just one single sign stimulus. (Ex. Migration of birds, butterflies, salmon etc.)

II. Forms of Communication of Animals

 Communication, the transmission of information between animals of the same species is essential to their survival and reproductive success. Effective communication relies on being correctly understood so the messages are often highly ritualized so they are not easily misinterpreted.

 Types of communication among animals: o Tactile messages – touching one animal by the other, like grooming behaviors of primates, vibrations of the female spider web by male spiders o Olfactory messages – Special scents are produced by some animals called pheromones to warn competitors, advertise potential mates, mark territories (ex. Dogs mark their territories, ants use pheromones to guide colony members etc.) o Auditory messages – using sound signals to communicate danger, potential mates, territories etc. (common among birds, chickadees, roosters, crows etc.) o Visual communication – Brightly colored animals are usually avoided by others – warning signals; animals also use visual clues to deceive others – eye spots on moths; some animals have visual cues that are used to attract the other gender – peacocks, lions etc. o