Ch 54-Community Ecology organism population community ecosystem biosphere

Community Ecology Community Community Ecology all the organisms that live together in a given place Community Ecology study of interactions among all populations in a common environment To answer: In what way do the populations interact?

Why is the beetle rolling the fecal ball? Niche An organism’s niche is its ecological role habitat = address vs. niche = job Ex: what it eats, what it lives in, time of day when active, behavior, etc… “How it fits into that ecosystem.” Why is the beetle rolling the fecal ball? Is that frog noctural?

Competition Interspecific competition- interaction between different species competing for the same resources, which limits their growth and survival (-/-) Ex- weeds and garden plants; grasshoppers and bison

Competitive Exclusion Principle No two similar species can occupy the exact same niche at the same time. Know: Fundamental niche vs Realized niche High tide Competitive Exclusion If Species 2 is removed, then Species 1 will occupy whole tidal zone. But at lower depths Species 2 out-competes Species 1, excluding it from its potential (fundamental) niche, so occupies it’s realized niche. Species 1 Low tide Chthamalus sp. Species 2 Fundamental niches Realized niches Semibalanus sp.

Reduce competition through microhabitats Resource partitioning-coexistence between species because one’s niche becomes ‘modified’ Reduce competition through microhabitats Resource partitioning among Dominican Republic lizards. Seven species of Anolis lizards live in close proximity, and all feed on insects and other small arthropods. However, competition for food is reduced because each lizard species has a different perch, thus occupying a distinct niche. Sympatric species often partition available resources, reducing competition between them.

Symbiotic Relationships competition (-/-) predation / parasitism (-/+) herbivory (-/+) commensalism (+/0) mutualism (+/+) lichens (algae & fungus) “Freddy fungus and Annie algae took a Lichen to each other!”

Symbiosis mutualism +/+ commensalism +/0 predation +/- competition -/-

Predation drives evolution Predators adaptations locate & subdue prey Prey adaptations elude & defend Predation provides a strong selection pressure on both prey & predator horns, speed, coloration spines, thorns, toxins Predation provides a strong selective pressure on prey populations. Any feature that would decrease the probability of capture should be strongly favored.

Defensive Adapations Mechanical Defense Chemical Defense Aposematic coloration Cryptic coloration Batesian Mimicry Mullerian Mimicry **All heavily rely on operant conditioning, trial and error learning, in order to be successful. They rely on predators learning what not to eat, and the predator remembering what not to eat.

black, red, orange & yellow means: DON’T EAT ME! Coloration Aposematic species resemble each other, whereas cryptic coloration means ‘camouflage’. Which pic is cryptic? black, red, orange & yellow means: DON’T EAT ME!

Batesian Mimicry Convergent evolution green parrot snake palatable or harmless species mimics a harmful model green parrot snake Hawkmoth larva puffs up to look like poisonous snake hawkmoth larvae

Which is the moth vs. the bee? Which is the fly vs. the bee? Nonpoisonous Mimic! Batesian mimicry Viceroy male edible Monarch male poisonous Which is the moth vs. the bee? Which is the fly vs. the bee? fly bee moth bee

Mullerian mimicry cuckoo bee yellow jacket two or more harmful species look like each other cuckoo bee yellow jacket - group defense advantage - predators may evolve innate avoidance

Coral snake is poisonous Red on yellow, poison fellow; red on black, safe from attack What kind of mimicry? Coral snake is poisonous King snake is not

Coevolution in Community Predator-prey relationships Parasite-host relationships Flowers & pollinators Long term evolutionary adjustments between species

Predator/Prey Coevolution… *TTX- toxin produced by newt Biowarfare arms race with garter snakes and newts.