Ch. 53

Communities Assembly of species living close enough together for possible interaction Differ in species richness Coevolution describes interactions involving reciprocal evolutionary adaptations in 2 species

Table 53.1 Interspecific Interactions

Interspecific Interactions Occur between populations of different species living together within a community Predation Parasitism

Interspecific Interactions - Predation Community interactions where one species eats another species Plant defenses whole plant is rarely consumed mechanical (thorns, hooks, spines) chemical (bad taste, produce abnormal development in insects that feed upon them)

Interspecific Interactions - Predation Animal defenses passive –hiding active –escaping, fleeing, self-defense, mobbing, alarm calls chemical –toxins (skunk, poisonous toads)

Figure 53.5 Camouflage: Poor-will (left), lizard (right)

Figure 53.6 Aposematic (warning) coloration in a poisonous blue frog

Interspecific Interactions - Predation Animal defenses Adaptive coloration cryptic (camouflage) aposematic (bright; coloring acts as a warning of another physical or chemical defense)

Figure 53.x1 Deceptive coloration: moth with "eyeballs"

Figure 53.7 Batesian mimicry

Figure 53.8 Müllerian mimicry: Cuckoo bee (left), yellow jacket (right)

Interspecific Interactions - Predation Mimicry bears a superficial resemblance to another species batesian: a palatable species mimics a bad tasting model mullerian: 2 or more unpalatable species, aposematically colored species resemble each other luring prey –tongue of snapping turtle looks like a worm

Interspecific Interactions - Parasitism Host is harmed in some way Endoparasites live within host’s tissues or body cavities tapeworms, Ascaris Ectoparasites attach or briefly feed on the external surface of the host mosquito, aphid

Interspecific Competitions Occurs when 2 or more species in a community rely on similar limiting resources 2 ways competition occurs interference (actual fighting over resources) exploitative (consumption or use of similar resources)

Interspecific Competitions Competitive exclusion principle predicts that 2 species competing for the same limiting resources cannot coexist in the same community one uses resources more efficiently so it reproduces faster

Interspecific Competitions Ecological niches sum of the total of an organism’s use of biotic and abiotic resources in its environment how an organism “fits” into its environment

Interspecific Competitions Fundamental niche resources a population is theoretically capable of using under ideal conditions Realized niche resources a population actually uses biological constraints –competition, predation, resource limitation

Interspecific Competitions If niches are identical for 2 species, cannot coexist Ecologically similar species can coexist

Interspecific Competitions Evidence for competition should be rare if competitive exclusion principle applies weaker competitor becomes extinct one of the species will evolve to use another set of resources huge impact on shaping niches

Interspecific Competitions Speciation Sympatric Allopatric

Interspecific Competitions Character displacement tendency for characteristics to be more divergent in sympatric populations of 2 species than in allopatric populations of the same species

Figure 53.x3 Commensalism between a bird and mammal

Symbiosis Form of interspecific interaction in which a host species and a symbiont maintain a close association Commensalism symbiont benefits/host unaffected cowbirds and cattle egrets This shows the symbiotic relationship commensalism, the bird gets food from the back of the cow but the cow is not affected

Symbiosis Mutualism a change in the symbiont affects the host root nodules of legumes Ants and acacia trees (video clip) When coyotes and badgers team up, the pairs track small, burrowing animals such as prairie dogs and ground squirrels. If the prey is above ground, the coyote usually chases it down, and the badger takes over the hunt if the prey descends underground. And not only do they find food together, but coyotes also have more success in this partnership than if they go it alone.prairie dogssquirrels

Symbiosis Parasitism host is harmed

Disturbance & Nonequilibrium Disturbances events that disrupt communities humans (most widespread agent) Succession process of change that results from disturbances in communities ecological primary secondary

Succession Ecological transition in species composition over time Primary begins in areas eventually barren of life due to lack of formed soil or on rubble Secondary if an existing community has been created by some disturbance that leaves the soil in tact

Disturbance and Nonequilibrium Recruitment colonization by species from distant areas not directly associated with the disturbed patch or its immediate vicinity