Community Community InteractionsInteractions

AP Biology - 2005AP Biology - 2005

CommunityCommunity

A division of an ecosystem that A division of an ecosystem that describes all of the organisms that describes all of the organisms that live in an arealive in an area

Focuses on interactions within the Focuses on interactions within the communitycommunity

Establishes a niche – a set of Establishes a niche – a set of conditions under which an organism conditions under which an organism existsexists

InteractionsInteractions

Focus on resources available in the communityFocus on resources available in the communityFoodFoodWaterWaterSpaceSpaceMatesMatesNesting sitesNesting sitesHiding placesHiding placesLightLightMacro and micronutrientsMacro and micronutrients

Limiting ResourcesLimiting Resources

There are only so many resources in a There are only so many resources in a community for all of the organismscommunity for all of the organisms

This limits the growth of populations of This limits the growth of populations of organisms within this communityorganisms within this community

It leads to specialized interactions It leads to specialized interactions within the members of this communitywithin the members of this community

( population dynamics)( population dynamics)

InteractionsInteractions

Interspecific – Between different Interspecific – Between different speciesspecies

Intraspecific – Within the same Intraspecific – Within the same speciesspecies

Interaction links and Interaction links and ExamplesExamples

http://eebweb.arizona.edu/Animal_Bhttp://eebweb.arizona.edu/Animal_Behavior/lycaenids/lycaen2.htmehavior/lycaenids/lycaen2.htm

Ecological relations( 1)Ecological relations( 1)

One organism benefits in a One organism benefits in a relationship the other is harmed or is relationship the other is harmed or is eateneaten

Example – predator – prey and parasite Example – predator – prey and parasite = host= host

Rating +/-Rating +/-Lynx and hare – predator and preyLynx and hare – predator and preyMalaria, red blood cell, and human – Malaria, red blood cell, and human –

parasite and hostsparasite and hosts

Cyclic predator-prey relationshipsCyclic predator-prey relationships

ExperimentExperiment

Experiment( con)Experiment( con)

Ecological relations( 2)Ecological relations( 2)

Two organisms compete for the same Two organisms compete for the same resources. This is known as competition.resources. This is known as competition.

Rating -/- or +/-Rating -/- or +/-

ExamplesExamples

Competition for mates – intraspecificCompetition for mates – intraspecific

Competition for space – plants – allelopathyCompetition for space – plants – allelopathy

Competition for nutrients and space – fungi Competition for nutrients and space – fungi and bacteria - antibioticsand bacteria - antibiotics

MutualismMutualism

Both organisms benefitBoth organisms benefit Rating +/+Rating +/+ Zooxanthellae and coral polypZooxanthellae and coral polyp Legumes and RhizobiumLegumes and Rhizobium Leaf cutter ant and fungal gardenLeaf cutter ant and fungal garden Ant and acaciaAnt and acacia

Leaf cutter ants and fungal gardensLeaf cutter ants and fungal gardenshttp://www.blueboard.com/leafcutters/what.hthttp://www.blueboard.com/leafcutters/what.ht

mm

http://cas.bellarmine.edu/tietjen/Ecology/fungus.htm

Ant and the AcaciaAnt and the Acacia

CommensalismCommensalism

One organism benefits – the other is One organism benefits – the other is neither harmed or benefitsneither harmed or benefits

+/0+/0 Examples – Pinnepidia crab and Examples – Pinnepidia crab and

tube wormtube worm

AmensalismAmensalism

Animals can have a negative effect Animals can have a negative effect on the environmenton the environment

0/-0/- Animals trampling the grass on the Animals trampling the grass on the

way to the water holeway to the water hole

ContradictionsContradictions

Not all organisms fit the description Not all organisms fit the description exactlyexactly

The definition for symbiosis is The definition for symbiosis is changing to include only those changing to include only those interactions between organisms of interactions between organisms of two different species whose two different species whose metabolism is altered by the metabolism is altered by the interactioninteraction

Competition- InterspecificCompetition- Interspecific

Allelopathy – How plants guard their Allelopathy – How plants guard their space by releasing molecules into space by releasing molecules into the environment that deters other the environment that deters other plants from occupying their spaceplants from occupying their space

http://www.units.muohio.edu/dragohttp://www.units.muohio.edu/dragonfly/itc/index.htmlxnfly/itc/index.htmlx

Intraspecific CompetitionIntraspecific Competition

Interspecific CompetitionInterspecific Competition

Barnacle species Barnacle species on a rocky shoreon a rocky shore

Establishes Establishes zonation of zonation of organismsorganisms

Niche determined Niche determined by ability to by ability to barnacles to barnacles to tolerate tolerate dehydrationdehydration

Competition may restrict species’ ranges.Competition may restrict species’ ranges. Two species of barnacles live on North Atlantic Two species of barnacles live on North Atlantic

seashores, but as adults, one species lives seashores, but as adults, one species lives higher in the intertidal zone than the other, with higher in the intertidal zone than the other, with little overlap between the two (a phenomenon little overlap between the two (a phenomenon called intertidal zonation).called intertidal zonation).

If one of the species is removed experimentally, If one of the species is removed experimentally, the vertical range of the other species becomes the vertical range of the other species becomes greater.greater.

The higher-zone barnacle outcompetes the The higher-zone barnacle outcompetes the other because it is more hardy when exposed to other because it is more hardy when exposed to air; in the lower zone, the other barnacle is able air; in the lower zone, the other barnacle is able to smother or crush higher-zone intruders.to smother or crush higher-zone intruders.

Barnacle CompetitionBarnacle Competition

Batesian MimicryBatesian Mimicry

Two different species Two different species resemble each other. resemble each other. One is unpalatable. One is unpalatable. The palatable The palatable receives the benefit receives the benefit of birds not wishing to of birds not wishing to eat it because they eat it because they have eaten the have eaten the unpalatable one with unpalatable one with bad results.bad results.

It pays to advertiseIt pays to advertise

Keystone SpeciesKeystone Species

http://www.prairiedogs.orhttp://www.prairiedogs.org/keystone.htmlg/keystone.html

A keystone species is a A keystone species is a species whose very species whose very presence contributes to a presence contributes to a diversity of life and whose diversity of life and whose extinction would extinction would consequently lead to the consequently lead to the extinction of other forms extinction of other forms of life. Keystone species of life. Keystone species help to support the help to support the ecosystem (entire ecosystem (entire community of life) of community of life) of which they are a part. which they are a part.

SuccessionSuccession

Succession begin when an area is Succession begin when an area is made partially or completely devoid made partially or completely devoid of vegetation because of a of vegetation because of a disturbancedisturbance. Some common . Some common mechanisms of disturbance are fires, mechanisms of disturbance are fires, wind storms, volcanic eruptions, wind storms, volcanic eruptions, logging, climate change, severe logging, climate change, severe flooding, disease, and pest flooding, disease, and pest infestation. infestation.

Plant SuccessionPlant Succession

Succession in a Glacial Succession in a Glacial MoraineMoraine

Degradative successionDegradative succession

The dead body of an organism is The dead body of an organism is reduced to basic molecules by reduced to basic molecules by decomposersdecomposers

Plants may produce litterPlants may produce litter Deciduous trees may produce layer Deciduous trees may produce layer

of litter - compostof litter - compost

CoevolutionCoevolution

The changes in one species may The changes in one species may affect the changes in another affect the changes in another species over timespecies over time

Adaptations may occurAdaptations may occur The organisms can develop a close The organisms can develop a close

associationassociation Pollinators and flowers a key Pollinators and flowers a key

example of coevolutionexample of coevolution

Yucca MothYucca Moth

http://waynesword.palomar.edu/ww0902a.htm

Yucca and mothYucca and moth

Female yucca moths only lay their Female yucca moths only lay their eggs in the ovules of yucca flowers. A eggs in the ovules of yucca flowers. A female Tegeticula( Yucca moth) lays female Tegeticula( Yucca moth) lays no more than 5 eggs in the ovules.no more than 5 eggs in the ovules.

After she has laid the eggs she After she has laid the eggs she scrapes the pollen from the flower’s scrapes the pollen from the flower’s anthers and flies to another Yucca anthers and flies to another Yucca where she transfers the pollen and where she transfers the pollen and lays 5 more eggslays 5 more eggs

Island BiogeographyIsland Biogeography

Immigration of mainland species to island – Immigration of mainland species to island – birds flying – other animals and plants and birds flying – other animals and plants and animals drifting on trees or floating on rafts animals drifting on trees or floating on rafts of vegetation in the currents in the oceanof vegetation in the currents in the ocean

( new plants and animals) Seeds also carried ( new plants and animals) Seeds also carried by birdsby birds

Isolation of species after immigrationIsolation of species after immigration Novel adaptationsNovel adaptations New species develop – allopatric speciationNew species develop – allopatric speciation New genetic speciesNew genetic species

GalapagosGalapagos

Darwin’s finches and the Darwin’s finches and the Galapagos IslandsGalapagos Islands

http://www.rit.edu/~rhrsbi/Galapagohttp://www.rit.edu/~rhrsbi/GalapagosPages/DarwinFinch.htmlsPages/DarwinFinch.html