organism population community Community Ecology ecosystem biosphere AP Biology Community Ecology . Community all the organisms that live together in a place . interactions To answer: In what way do the . Community Ecology populations interact? study of interactions among all populations in a common environment
AP Biology Niche . An organism’s niche is its ecological role habitat = address vs. niche = job
High tide
Competitive Exclusion If Species 2 is removed, then Species 1 will occupy Species 1 whole tidal zone.Low tide But at lower depths Species 2 out-competes Species 1, Chthamalus sp. excluding it from its potential (fundamental) niche. Species 2
Fundamental Realized AP Biology niches niches Semibalanus sp. Ecological niche: the sum total of an organism’s use of abiotic/biotic resources in the environment . Fundamental niche = niche potentially occupied by the species . Realized niche = portion of fundamental niche the species actually occupies
High tide High tide Chthamalus Chthamalus Balanus realized niche Chthamalus Balanus fundamental niche realized niche Ocean Low tide Ocean Low tide
AP Biology Realized - max. range that a species has occupied in Interspecificreality due Interactions to competition/other factors Potential/Fundamental Niche - max. range that a I) Competitionspecies (can-/- occupy)
Realized and Potential Niche
AP Biology Niche & competition . Competitive Exclusion
No two similar species can occupy the same niche at the same time
AP Biology No two organisms can have the same ecological niche
Principle of Competitive Exclusion
AP Biology And Resource Partitioning No two organisms can have the same ecological niche - Competitive Exclusion
https://www.youtube.com/watch?v=rZ_up40FZVw Competitive exclusion https://www.youtube.com/watch?v=0w5-UfEi470 Resource partitioning
QuickTime™ and a QuickTime™ and a TIFF (Uncompressed) decompressor TIFF (Uncompressed) decompressor are needed to see this picture. are needed to see this picture.
Character Displacement - species living close together differ more in traits than AP Biology those living far away Resource partitioning Reduce competition through microhabitats
“the ghost of competition past”
AP Biology • Interspecific competition: resources are in short supply
▫ Species interaction is -/- • Competitive exclusion principle: Two species cannot coexist in a community if their niches are identical.
▫ The one with the slight reproductive advantage will eliminate the other • Resource partitioning: differences in niches that enable similar species to
AP Biologycoexist Interspecific interactions . Symbiotic interactions
competition (-/-) . compete for limited resource . competitive exclusion!
predation / parasitism (-/+)
mutualism (+/+) . lichens (algae & fungus)
commensalism (+/0) . barnacles attached to whale
AP Biology Symbiosis mutualism +/+
…not very funny for a clown fish commensalism +/0
APpredation Biology +/- competition -/- What relationship is this?
AP Biology Predation drives evolution . Predators adaptations locate & subdue prey . Prey adaptations elude & defend Predation provides a strong selection horns, speed, coloration pressure on both prey & predator spines, thorns, toxins
AP Biology Anti-predator adaptations . Hide from predators
avoid detection
camouflage . Warn predators
advertise how undesirable you are as prey
aposematic coloration . apo = away & sematic = sign/meaning . Batesian mimicry . Mullerian mimicry
AP Biology Interspecific Interactions 1)Cryptic . Predation -ways to avoid it Coloration = camouflage
AP Biology Defense mechanisms . Camouflage
cryptic coloration whipporwill
AP Biologylizard toad Interspecific Interactions . Avoiding Predation 2)Aposematic Coloration= warning coloration
AP Biology Common warning coloration . Aposematic species come to resemble each other
black, red, orange & yellow means: DON’T EAT ME!
AP Biology Interspecific Interactions . Avoiding Predation 3)Batesian Mimicry – harmless species mimics harmful
AP Biology Convergent evolution Mimicry palatable or harmless species Batesian mimicry mimics a harmful model
green parrot snake Hawkmoth larva puffs up to hawkmoth larvae look like poisonous snake AP Biology Convergent evolution Batesian mimicry
Monarch male Viceroy male poisonous edible Which is the mothfly vs. vs. the the bee? bee?
AP Biology fly bee moth bee Interspecific Interactions . Avoiding Predation 4)Mullerian Mimicry – 2 unpalatable species resemble each other. Why?
AP Biology Mullerian mimicry two or more protected species look like each other
cuckoo bee
yellow jacket - group defense? Mullerian mimicry AP Biology - predators may evolve innate avoidance What kind of mimicry?
Coral snake King snake is not is poisonous
Red on yellow, poison fellow; red on black, safe from attack
AP Biology Interspecific Interactions . Predation (+/-) Parasitism is a type of predation “Scientists have discovered a way to kill the malaria parasite - by targeting its sweet tooth.” –BBC News
AP Biology Interspecific Interactions
. Predation (+/-) Parasitism
AP Biology Interspecific Interactions
. Predation (+/-) Parasitism - types: a) Ectoparasite b) Endoparasite
c) Parasitoidism- Nasonia AP Biology AP Biology Interspecific Interactions III) Mutualism (+/+) Coevolution- change in one species affects evolution of another species
Ex. Nitrogen fixing bacteria in the root of legumes, bees and flowers, cellulose digesting bacteria in gut of cows
AP Biology Coevolution in Community . Predator-prey relationships . Parasite-host relationships . Flowers & pollinators
APLong Biology term evolutionary adjustments between species Interspecific Interactions . Commensalism (+/0)
One benefits, one neithergains/loses: dung beetle, birds on cattle, Nemo AP Biology and anemone! Symbiosis - term describes ‘living together’
Predation (+/-)
CommensalismAP Biology (+/0) Mutualism (+/+) Trophic Structures
. The trophic structure of a community is determined by the feeding relationships between organisms. . Trophic levels = links in the trophic structure
. The transfer of food energy from plants herbivores carnivores decomposers is called the food chain.
AP Biology What limits the length of a food chain? . Inefficiency of energy transfer along chain . Long food chains less stable than short chains
Fig. 53.10 AP Biology . Dominant species: has the highest biomass or is the most abundant in the community . Keystone species: exert control on community structure by their important ecological niches
Loss of sea otter increase sea urchins, destruction of kelp forests
Grizzly bear (transfer nutrients from sea land by salmon diet) AP Biology Prairie dogs (burrows, soil aeration, trim vegetation) Dominant species - highest biomass (sum of weight of all individuals in a population)
Sugar maple - shade out other plants and take in most water
What happens if dominant species is removed? AP BiologySomething else takes over usually Can a species be non-dominant and still control the community?
. Sea star preys on mussels . Mussels eat algae/small invertebrates . Sea star’s absence results in decrease of algae/invertebrates in the community AP Biology Keystone species Pisaster ochraceous . Influential ecological role
exert important regulating effect on other species in community Sea star keystone species increases diversity increases diversity diversity decreases in habitat mussels out-compete other species
AP Biology Washington coast Keystone species
Sea otter is a keystone predator in North Pacific
What is the impact of the Orca whale?
AP Biology Keystone species Beaver is a keystone species in Northeast & West
damsAP Biology transform flowing streams into ponds creating new habitat Disturbances influences species diversity and composition . A disturbance changes a community by removing organisms or changing resource availability (fire, drought, flood, storm, human activity)
. Ecological succession: transitions in species composition in a certain area over ecological time
AP Biology Disturbances – environmental changes (volcanoes, fires…..!) Density Independent Factor - keeps population size in check; dominant species growth is curbed
AP Biology Non-equilibriumFig. 53.16 Succession – Transition in Species Composition Over Ecological Time; Predictable order of species (first - easily dispersed species; later - superior competitors) 1980 1981After Before
AP Biology Ecological succession . Sequence of community changes
transition in species composition over time . years or decades
usually after a disturbance
Mt.AP St.Biology Helens Succession of species pioneer species compete well in high sunlight
lichens & mosses grasses more shade tolerant species climax forest shade tolerant species stable community
AP Biology bushes & small trees trees What causes succession? . Tolerance early species are weedy r-selected tolerant of harsh conditions . Facilitation & Inhibition early species facilitate habitat changes . change soil pH . change soil fertility . change light levels allows other species to out-compete
AP Biology Primary succession . Begins with virtually lifeless area without soil, then…
make bacteria soil lichens & { mosses grasses shrubs trees
AP Biology Primary Succession
. Plants & animals invade where soil has not yet formed
Ex. colonization of volcanic island or glacier
AP Biology Primary Succession Soil has been A) Glaciation removed B) Volcanic Lava Flows C) Volcanic Explosions D) Faulting raising sea floor
AP Biology Primary Succession -soil ‘gonner’
Soil has been removed . by volcano
1) Short lived weed growing through the ash
Early successional Community
AP Biology Primary Succession
. 2) Herbaceous plants and grasses
AP Biology Primary Succession
. 3) Shrubs (willow) and short lived trees (alder)
Mid successional Community
AP Biology Primary Succession
Climax Community
?????? 4) Long-lived trees (fir, hemlock, pine)
AP Biology Climax forest . Plant community dominated by trees . Representing final stage of natural succession for specific location
stable plant community
remains essentially unchanged in species composition as long as site remains undisturbed . birch, beech, maple, hemlock . oak, hickory, pine
AP Biology Climax forest taiga The species mix of climax forest is dependent on the abiotic factors of the region
. solar energy levels . temperature . rainfall . fertility & depth of soil
temperate deciduous forest AP Biology birch, beech, maple, hemlock Secondary succession . Existing community cleared, but base soil is still intact burning releases nutrients formerly locked up in the tissues of tree
the disturbance starts the process of succession over again AP Biology Secondary Succession
. Occurs when existing community is cleared by a disturbance that leaves soil intact
Ex. abandoned farm, forest fire
Soon after fire. As this photo taken soon after the fire One year after fire. This photo of the same general area shows, the burn left a patchy landscape. Note the taken the following year indicates how rapidly the com- unburned trees in the distance. munity began to recover. A variety of herbaceous plants, AP Biology different from those in the former forest, cover the ground. Secondary Succession- soil ‘Okey dokey’
Soil is intact A) Forest Fires B) Disease C) Climatic Conditions - Hurricane, tornado, drought, windstorms, etc...... D) Human Disturbance – urban development, clearing woods, grazing etc......
AP Biology Disturbances as natural cycle . Disturbances are often necessary for community development & survival - release nutrients - increases biodiversity
fire climax forests
- increases habitats - rejuvenates community AP Biology Jack Pine Fire climax species adaptations to survive and reproduce in areas than experience frequent fires
AP Biology When people don’t learn ecology! Building homes in fire climax zones
preventing fires makes next year’s fire much worse!
AP Biology Soil concentrations of nutrients show changes over time.
AP Fig.Biology 53.20 Compare the Kentucky old growth forest and Crater lake National park.
What happened in Crater lake national forest?
AP Biology Characterizing a community . Community structure
species diversity . how many different species
composition . dominant species . most abundant species or highest biomass (total weight) . keystone species . changes over time succession
AP Biology Species diversity greater diversity = greater stability . Greater biodiversity offers: more food resources more habitats more resilience in face of environmental change
AP Biology The impact of reduced biodiversity compare these communities
suburbanagricultural lawn “old field” “monoculture” . Irish potato famine AP Biology . 1970 US corn crop failure