Creative Community Ecology Ch 54 notes. I. Introductory Vocabulary Community group of populations...

Creative Creative Community Community EcologyEcologyCh 54 notesCh 54 notes

I. Introductory I. Introductory VocabularyVocabulary

Community Community group of populations in an area or group of populations in an area or

habitathabitat

II. Interspecific II. Interspecific Interactions Interactions

Relationships between the species Relationships between the species of a community of a community

Types include:Types include:

CompetitionCompetition -/--/-

PredationPredation +/-+/-

MutualismMutualism +/++/+

CommensalismCommensalism +/0+/0

A. Competition A. Competition

Detrimental to both species Detrimental to both species Organisms compete for available Organisms compete for available

resources such as food, water, shelter, resources such as food, water, shelter, sunlightsunlight

1. Competitive exclusion 1. Competitive exclusion principle principle

Two species so similar that they Two species so similar that they compete for the same limiting compete for the same limiting resource cannot coexist in the same resource cannot coexist in the same placeplace

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2. Ecological niche 2. Ecological niche

sum total of a species’ use of biotic and sum total of a species’ use of biotic and abiotic resources – how an organism fits abiotic resources – how an organism fits into it’s ecosystems (it’s role)into it’s ecosystems (it’s role)

two species cannot coexist in a two species cannot coexist in a community if they community if they occupy the same occupy the same nicheniche

3. Resource partitioning 3. Resource partitioning

if two species have the same niche, the if two species have the same niche, the less competitive one will either be driven less competitive one will either be driven from the area, or will evolve through from the area, or will evolve through natural selection to use a different set of natural selection to use a different set of resourcesresources

4. Character 4. Character displacement displacement

The tendency for characteristics The tendency for characteristics to be more divergent in to be more divergent in sympatric (geographically sympatric (geographically overlapping) populations of two overlapping) populations of two species than in allopatric species than in allopatric (geographically separate) (geographically separate) populations of the same two populations of the same two speciesspecies

B. Predation B. Predation

beneficial to one organism but not the beneficial to one organism but not the otherother

one organism eats another one organism eats another includes herbivory (eating part of a plant), includes herbivory (eating part of a plant),

parasitism (parasite living on host) parasitism (parasite living on host)

1. Predator adaptations 1. Predator adaptations

acute senses to locate preyacute senses to locate prey many have claws, teeth, fangs, stingers, many have claws, teeth, fangs, stingers,

poisonpoison generally fast and agile if they have to generally fast and agile if they have to

pursue preypursue prey

2. Animal defenses 2. Animal defenses against predators against predators

Passive defenses: hiding, chemical Passive defenses: hiding, chemical toxinstoxins

Active defenses: escaping, defending Active defenses: escaping, defending themselves, warning callsthemselves, warning calls

Animal defenses against Animal defenses against predatorspredators

Adaptive colorationAdaptive coloration camoflauge – cryptic coloration to blend with camoflauge – cryptic coloration to blend with

environmentenvironment aposematic coloration – bright coloration of aposematic coloration – bright coloration of

animals that have animals that have chemical toxins chemical toxins dangerous to predatorsdangerous to predators

Can you see me?

Animal defenses against Animal defenses against predatorspredators Mimicry – “copycat” adaptationMimicry – “copycat” adaptation

Batesian mimicry – harmless species mimics Batesian mimicry – harmless species mimics a harmful model (ex. larvae puffs up and a harmful model (ex. larvae puffs up and resembles cobra)resembles cobra)

I’m Harmless!!!

Animal defenses against Animal defenses against predatorspredators

Mullerian mimicryMullerian mimicry two unpalatable two unpalatable species resemble species resemble each other each other

predators learn predators learn more quickly more quickly about danger of about danger of the appearancethe appearance

3. Parasites and 3. Parasites and Pathogens as predators Pathogens as predators

host harmed in the processhost harmed in the process endoparasites – live within their endoparasites – live within their

host (tapeworm)host (tapeworm) ectoparasites – feed on external ectoparasites – feed on external

surface of host (mosquito)surface of host (mosquito) parasitoidism – insects lay eggsparasitoidism – insects lay eggs

on living hoston living host

4. Herbivory4. Herbivory

Organism eats part of a plant or algaOrganism eats part of a plant or alga ex. Cattle, many invertebrates, manateeex. Cattle, many invertebrates, manatee Herbivores may have adaptations such Herbivores may have adaptations such

as chemical sensors to detect toxins, as chemical sensors to detect toxins, specialized teethspecialized teeth

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5. Plant defenses 5. Plant defenses against herbivores against herbivores

Chemical toxinsChemical toxins SpinesSpines ThornsThorns Used since plants cannot Used since plants cannot

run from predatorrun from predator

C. Mutualism C. Mutualism

interspecific interaction that is beneficial interspecific interaction that is beneficial to both species to both species

often requires coevolution of adaptations often requires coevolution of adaptations in both species in both species

if one is harmed, the other is usually if one is harmed, the other is usually harmed as well harmed as well

Examples of MutualismExamples of Mutualism

microorganisms in digestive system of microorganisms in digestive system of termites and ruminants (help digest termites and ruminants (help digest cellulose) cellulose)

Photosynthesis by algae in tissue of coralPhotosynthesis by algae in tissue of coral

There’s bacteria in my bellyWho knew!!!

4. Commensalism 4. Commensalism

interaction between species that interaction between species that benefits only one of the species but no benefits only one of the species but no harm to the otherharm to the other

ex. algae growing on shell, birds eating ex. algae growing on shell, birds eating insects flushed up by cowsinsects flushed up by cows

MOOOOYummy Bugs

III. Biodiversity III. Biodiversity

Species diversity in a community Species diversity in a community

Species DiversitySpecies Diversity

The variety of different kinds of The variety of different kinds of organisms that make up the communityorganisms that make up the community

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Species Diversity Species Diversity

Species RichnessSpecies Richness number of species that a community can number of species that a community can

containcontain

Relative AbundanceRelative Abundance The proportion of each species represents of The proportion of each species represents of

all individuals in the communityall individuals in the community

Which community is more Which community is more diverse???diverse???

Community 1

Species A Species B

Species C Species D

Community 2Species A Species B

Species C Species D

Community 1 and 2 are equal in their species Community 1 and 2 are equal in their species richness (both have 4 different species)richness (both have 4 different species)

Community 1 is more diverse because there is Community 1 is more diverse because there is equal representation of all 4 equal representation of all 4

Community 2 has a large amount of Species ACommunity 2 has a large amount of Species A Community 1 has greatest heterogeneity (looks Community 1 has greatest heterogeneity (looks

at species number and relative abundanceat species number and relative abundance

IV. Trophic structures IV. Trophic structures

feeding feeding relationships relationships between between organismsorganisms

Quaternary Consumer(Carnivore)

Tertiary Consumer(Carnivore)

Secondary Consumer(Carnivore)

Primary Consumers(Herbivores/Zooplankton)

Primary Producers(plant/phytoplankton)

A. Food Chain A. Food Chain

Transfer of food energy from it’s source in Transfer of food energy from it’s source in plants through herbivores to carnivores and plants through herbivores to carnivores and eventually to decomposers eventually to decomposers

Each link makes a trophic levelEach link makes a trophic level Each food chain has only four or five links due Each food chain has only four or five links due

to inefficient energy transfer as you move up to inefficient energy transfer as you move up the chain the chain

Longer food chains may not be able to recover Longer food chains may not be able to recover as as quickly from environmental changequickly from environmental change

B. Food Web B. Food Web

more than one more than one food chain food chain hooked togetherhooked together

Dominant species Dominant species

have the highest abundance or the have the highest abundance or the highest biomasshighest biomass

exert control over occurrence and exert control over occurrence and distribution of other speciesdistribution of other species

Keystone species Keystone species

exert control on community structure by their exert control on community structure by their ecological role (niche)ecological role (niche)

may help to maintain diversity and balance in may help to maintain diversity and balance in communitycommunity

ex. sea otter eats sea urchin eats algaeex. sea otter eats sea urchin eats algae remove sea otter (keystone) and algae remove sea otter (keystone) and algae

population goes downpopulation goes down add sea otter – algae population increasesadd sea otter – algae population increases

Example of Keystone Example of Keystone SpeciesSpecies

Removal experimentRemoval experiment Robert Paine and Sea Star – Robert Paine and Sea Star – Pisaster Pisaster is is

a keystone predator of musselsa keystone predator of mussels With With PisasterPisaster – many species able to – many species able to

coexistcoexist Without Without PisasterPisaster – mussels able to – mussels able to

overtake area eliminating many other overtake area eliminating many other speciesspecies

Testing a Keystone Predator Hypothesis

0

10

20

30

1960 1965 1970 1975

Year

Numb

er o

f sp

ecie

s pr

esen

t

With Pisaster

Without Pisaster

Foundation SpeciesFoundation Species

Exert influence on a community by Exert influence on a community by causing physical changes in the causing physical changes in the environmentenvironment

ex. Beaver building a dam can transform ex. Beaver building a dam can transform the landscape on both sidesthe landscape on both sides

Can be positive or negative on other Can be positive or negative on other speciesspecies

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V. Disturbances V. Disturbances

storms, fires, floods, drought, storms, fires, floods, drought, overgrazing, human activities overgrazing, human activities

may upset balance or equilibrium in may upset balance or equilibrium in communitycommunity

Ecological succession Ecological succession

transition in the biological species transition in the biological species composition of a community usually composition of a community usually following a disturbancefollowing a disturbance

Primary succession Primary succession

succession that begins in a virtually succession that begins in a virtually lifeless area where soil lifeless area where soil has not yet has not yet formed (like Hawaii)formed (like Hawaii)

Autotropic bacteria Autotropic bacteria lichens/mosses lichens/mosses soilsoilother plantsother plants animals animals

Secondary succession Secondary succession

existing community has been cleared by existing community has been cleared by a disturbance that leaves soil intacta disturbance that leaves soil intact

Often these areas return to something Often these areas return to something like the original statelike the original state