I. I.Community Ecology A. A.Competition 3. 3.Resource partitioning Competitive exclusion can be minimized if competing species modify niches to reduce overlap Usually involves dividing resource

Fig Anolis Dominican Republic

I. I.Community Ecology A. A.Competition 4. 4.Character displacement Resource partitioning may lead to directional selection on one or both species Directional selection may lead to divergence in traits

Fig. 54.4

I. I.Community Ecology B. B.Predation Involves consumption of prey by predator Predator usually has adaptations to facilitate capture of prey Natural selection acts on both predator and prey Coevolution 1. 1.Strategies a. a.Pursuit predation Predators chase prey to capture them Predator usually faster, stronger, &/or more agile than prey Some species hunt in groups b. b.Ambush predation Predators lie in wait for prey Predators usually camouflaged or concealed May involve lures c. c.Aggressive mimicry Ex: Bolas spider mimics odor of female moths to attract male moths

I. I.Community Ecology B. B.Predation 2. 2.Predator avoidance a. a.Escape Running/Swimming/Flying away b. b.Mechanical defenses Ex: Porcupine quills, armadillo armor c. c.Social behavior Ex: Schooling, standing watch d. d.Chemical defenses Ex: Poison dart frog, skunk e. e.Defensive coloration

Cryptic coloration - Canyon tree frog Aposematic coloration - Poison dart frog Batesian mimicry Fig Müllerian mimicry

Batesian Mimicry Sam Crothers

I. I.Community Ecology C. C.Herbivory Consumption of plants by animals Most herbivores are small Ex: Insects, snails/slugs Herbivores adapted to consume plants Some plants have anti-herbivore defenses Physical – Ex: Thorns, spines Chemical – Ex: Nicotine in tobacco, pyrethrins in chrysanthemums Coevolution has affected herbivore evolution Ex: Monarch butterfly caterpillars can eat milkweed Toxic to most herbivores Nearly exclusive access to food source Can sequester noxious compounds for defense

I. I.Community Ecology D. D.Parasitism Parasite benefits at expense of host Host harmed in process Ex: Tapeworm absorbs nutrients from host digestive system Endoparasites – Live within body of host Ectoparasites – Live outside body of host Parasitoids – Lay eggs on/in host; larvae feed on host, eventually killing host Many parasites have complex life cycles Fig

Fig Schistosoma mansoni

I. I.Community Ecology E. E.Disease Widespread disease outbreaks may alter community composition and dynamics Ex: Dutch elm disease Ex: Sudden oak death Ex: Avian flu Ex: West Nile virus

I. I.Community Ecology F. F.Mutualism Symbiotic relationship in which both partners benefit Ex: Ants & acacia trees Ex: Nitrogen fixing bacteria (Rhizobium) & legumes Ex: Zooxanthellae & reef-building corals Ex: Mycorrhizae & plants Ex: Anemones & clownfish

I. I.Community Ecology G. G.Commensalism One organism benefits, other isn’t harmed or helped Ex: Cattle egrets and cowbirds & ungulates (expose insects while grazing) Hard to document (both species usually affected to some degree) Ex: Some commensal birds may remove ticks & other ectoparasites from herbivores