Lecture 31 + 32: Community Ecology
Lecture 31 + 32: Community Ecology Bio 211
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This 0 page Class Notes was uploaded by Kiara Reyes on Sunday November 22, 2015. The Class Notes belongs to Bio 211 at Northern Illinois University taught by Catherine Ausland in Fall 2015. Since its upload, it has received 31 views. For similar materials see Funds of Organismal Biology Lab in Biology at Northern Illinois University.
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Date Created: 11/22/15
Lecture 31 8 32 Community Ecology 1 Community Coexisting Organisms all the different species in 1 place lots of different types of interaction EX Competition Symbioses Mutualism Predation Parasitism Herbivory Interaction PositiveNegative Outcome Frame Work between Organism 1 and Organism 2 Mutualism Predation Parasitism Herbivory Predation Competition Parasitism Herbivory 2 Competition When greater than or equal to 2 organisms use same resources and the resources is limited in short supply A 2 ways to compete 1 Fights Territoriality or via Chemical 2 Use resource 1 before competitor B Competition with whom 1 Interspecific Different Species 2 Intraspecific Same Species C Population growth models considered just one species but competition is one factor that can lead to logistic growth Niche all the biotic and abiotic resources an organism uses in environment What it eats What it seeks shelter Abiotic factors it can withstand temperature rain Time of day and year it is active or reproduces Niche Overlap determine the strength of competition between species Species that have an overlap have a greater and stronger Niche overlap The range of conditions a species had the potential to live Fundamental Niche where it can live The portion of those conditions that is actually occupied Realized Niche where it really live in Competitive Exclusion Range is limited from mix organisms already living there Barnacles Have jointed legs and are closely related to pillbugs and shrimp Classi cation Phylum Arthropoda Class Crustacea Inhabit Intertidal Zone Competition Yes Interspecific Different realized vs Fundamental Niche At least for upper species Ex Chthamalus top and Balanus bottomgt Balanus removedgt Chthamalus grew Competitive Exclusion is a short term outcome of competitions result from individual responses to competitors Here via Deaths but could also cease to coexist if 1 species emigrates Long Term evolutionary outcomes of interspecific competition 1 2 Selection may favor use of resource for which there is less competition gtNiche shifts resource partitioning Ex 2 different lizardsgt can both live in treesgt 1 in tree and 1 on fence Expect such selection to be stronger in sympatry same places than in allopatry different places If its shift in trait Ex in beak depth called characteristic displacement trait change or displacement 3 Predation Parasitism and Herbivory Predation Prey is killed and consumed Parasitism Obtain resources from host but don t always kill it Herbivory Plant is consumed partly or entirely Effects is short term ecological time Changes in population size for both pray and predators Reduces fitness and thus population of a parasites host Reduce seed production in plants that suffer herbivory Ex Cucumber plants whose leaves get eaten in June produce few fruits later on Effects in Evolutionary time 1 Adaptation Includes coevolution Ex Newt s skin contains an usual Toxin not usually seen in newts For most predators lethal or paralysis because toxin block sodium channels in cell membranes lipid bilayergt Often allow newt to escape But some garter snakes tolerate toxin have few amino acid difference in their sodium channel protein Other Adaptations against predators Aposematic Coloration Bright Color Warning Coloration Increased tness because predators associative learning is quicker is signal is strong brighter color toxic Cryptic Coloration Dark Color to hide works for predators and pray Batesian Mimicry BS something nontoxic looks like something toxic Mullerian Mimicry quotMutualquot 2 species are the same 2 species are toxin 4 Mutualism Both species tness is increased by interaction Ants get shelter in the thorns and food nectar and protecting Acacia tree gets protection against herbivores and plant competitors Other widespread mutualism Mycorrhizal Fungi and Rhizobium Seed Dispersal Animals get food fruit Plants get their seeds moved around when animals poop Pollination Insects get food nectar pollen Plants sendreceive pollen to reproduce Fitness 5 Community Composition The number of species in a community Species richness EX Community 1 A 25 B 25 C 25 D 25 Some species are numerous some are rare different in relative abundance numbers of individuals Ex Community 2 A 80 B 5 C 5 D 10 Together there determine the species diversity in a community Microbial ecologists use molecular tools to describe communities of bacteria and archaea Higher Diversity communities tend to be more stable Less affected by disturbances like drought Less likely to be invaded by nonnative species In streams higher species diversity result better water quality by cleaning up nitrate pollutants Trophic Structure Food Chain about 10 transfer of energy as from 1 trophic level to the one above thus usually less than or equal to 5 trophic levels EX Plant primary producersgt Grasshopper primary consumersgt Mouse secondary consumersgt Rattle Snake tertiany consumersgt Hawk quaternary consumers Food Web diagram of feeding trophic relationship in a community or around the world Control of Community Structure What determines abundances at each trophic level Topdown controls goes from higher to lower trophic levels EX nutrientslt vegetationlt herbivoreslt predators Bottomup controls goes from lower to higher trophic levels EX nutrientsgt vegetationgt herbivoresgt predators Communities are not always at equilibrium stay the same ecological succession sequence of community changes Primary succession taking almost everything from the environment near nothing left behind Secondary succession where soil and some species remain after a disturbance EX BeforeAfter affects of Fire forest Hurricane 6 Community Ecology and Medicine Pathogens can play important role in ecology communities A disease causing microscope including causing disease in human or other species When spread from animals to humans called Zoonotic Pathogens Includes Lyme Disease H5N1 quotbird u West Nile Virus Humans ltgt TicksBugs HumanVector Interaction TicksBugs ltgt MouseDeer HostVector Interaction PlantsTrees ltgt MouseDeer Animal Habitat Interaction