Community Ecology - Lecture notes 21 PDF

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Dr. Daniel Stern Cardinale...

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Community Ecology Friday, December 2, 2016

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Community Interactions ○ Cc types of interactions Species Diversity ○ CC abundance, richness Trophic structure ○ IOV, EVAL trophic structures Community Development ○ CC, primary, secondary succession Intro ○ Community-association of populations of different species that live and interac same place at the same time ○ Community ecology- study if interactions that determine distribution and abun individuals and populations ○ Resource-anything form environment that meets needs of a species ○ Ecological niche-role of a species within structure and function of community Community Interactions ○ 3 main types of interactions between species a. Competition-two or ore individuals attempt to use the same resource i. Use by one decreases availability for others ii. -/- interaction; both participants adversely affected iii. 2 types 1) Intraspecific Competition a) Competition between members of the same species/populati 2) Interspecific Competition a) Competition between members of different species iv. Importance of competition 1) Considered most important determinant of: a) # of species in community b) Size of each population 2) Requires overlapping niches to operate v. Competitive exclusion

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1) 2 species with absolutely identical ecological niches cannot coexist 2) Competing for same limiting resources 3) One wins, one loses 4) Demonstrated with paramecium vi. Species with similar niches 1) Can coexist if there are non-overlapping parts of niches 2) Selection can result in one using a different set of resources vii. Competitive exclusion partially results 1) One species excludes other from part of fundamental niche 2) Realized niche 3) Can happen within species a) Sympatric speciation viii. Resource partitioning 1) Differentiation of niches that allows similar species to coexist ix. Character displacement 1) Happens when different species overlap some of the time 2) Tend to differ in structural, ecological, or behavioral traits in overla 3) Can have similar trains in non-overlapping area b. Predation i. Consumption of one species by another, predator eats prey ii. +/- interaction; predator benefits, pre adversely affected iii. Often leads to coevolution 1) 2 or more species that are evolving in response to one another 2) Each exerts a strong selective force on the other-->evolution due to a) Species A evolves an adaption in response to species B b) Species B evolves in response to the adaption of Species A i) cycle 3) Predator gets better at catching prey 4) Pre gets better at avoiding predator iv. Adaption in predators 1) Acute senses 2) Claws, fangs, poison 3) Fast, agile 4) Camouflage if ambushes prey v. Adaptions in prey 1) In animals a) Mechanical defense, ie. Porcupine b) Chemical defense ie. Skunk

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Coloration i) Aposematic coloration, poison dart frog } Warning colration--conspicuous colors or pattern advertise bad taste or toxicity to potential predat } Ex. Milkweeds produce alkaloids and cardiac glyc } Toxic to all but a very few insects--little competiti } Will become toxic to predators } Advertises it's identity very clearly ii) Cryptic coloration, canyon tree fro } Camouflage, blend into environment d) Mimicry-visual similarity of one species to another which pro both i) 2 types } Batesian-defenseless species that looks like a dan species – Ex. King Snake looks like Coral Snake – Model density must be higher than mimic } Mullerian – Different species resemble each other, all w defenses – Advantageous to all, because predatory on learn 1 coloration and avoids all e) Other defense mechanisms i) Fleeing-run and hide, sometimes distract One. Ink, autonomy ii) Living in groups One. More likely to notice predator, less likely to be ea f) Often used in combination In plants a) Herbivory-organisms eats part of plant or alga; +/- interaction b) Cant escape, but often have defenses i) Physical/mechanical-spines, thorns, thick waxy leaves ii) Chemical-bad taste or toxicity

Symbiosis i. Intimate, long term relationship between 2 or more species ii. Usually involves 1 species living on or in the other iii. Parasitism 1) +/-, parasite benefits, host is harmed, rarely killed 2) Ex Heartworms tapeworms ectoparasites

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2) Ex. Heartworms, tapeworms, ectoparasites iv. Mutualism 1) +/+ interaction=both benefit, often depend one each other v. Commensalism 1) +/0 integration, one benefits, neutral of the other 2) Ex. Tree and epiphyte, egrets and African buffalo Species diversity ○ The variety of different kinds of organisms that make up a community ○ 2 components a. Species Richness i. Number of different species within a community ii. Rainforest-high species richness iii. Mountain top-low species richness b. Relative Abundance i. Also called species evenness ii. Proportion of all individuals n community that each species represents iii. Ex. Of difference fig 54.11 Trophic structure ○ Feeding relationships between organisms in a community ○ Who eats whom ○ E from food transferred up trophic levels a. Food Web i. Food chains that are linked ii. 1 species can exist at 1> tropic level b. Limits i. Food chains/webs can only have so many layers ii. Energetic hypothesis-length limited by inefficiency of E transfer iii. Only about 10% of E stored at each level transferred to next iv. Prediction: higher photosynthetic production--> longer food chains c. Species with large impact i. Dominant species-highest abundance or biomass, but not critical to com structure ii. Keystone species-often not abundant, but strong influence on communit 1) Critical ecological role Community development ○ Ecological succession § Process of species turnover in an area ○ Continuous process of community development over time ○ 10s, 100s, 1000s or years, not millions

unity structure

10s, 100s, 1000s or years, not millions Usually described in terms of plant species, but animals also change Primary succession i. Change in species composition over time in habitat not preciously inhabit ii. Ex. New volcanic island iii. Bare rock--> first organisms-->create soil--> larger plants b. Secondary succession i. Change in species composition over time in preciously inhabited habitat ii. Soil already present ○ ○ a.

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