Interspecific interactions Competition (-/-) Predation (+/-) Herbivory (+/-) Symbiosis Mutualism (+/+) Commensalism (+/0) Parasitism (+/-) Niche An area (environment) where an organism utilizes the biotic and abiotic resources; ecological role Resource Partitioning Character displacement Diff in body structures and the resources they use Darwins Galapagos finches adaptations for eating diff sized seeds Competitive exclusion principle No two species can occupy the same niche at the same time, competing for the same limiting resources Predator kills another, its prey Adaptations Predator Claws, teeth, fangs, stingers, venom (poison) Prey Cryptic coloration = camouflage Aposematic coloration = chemical defenses w/ bright color patterns Batesian mimicry = harmless sp resembles harmful one Mullerian mimicry = 2+ harmful sp resemble one another Organisms eat parts of a plant or algae Smell and chemical sensors allow for distinction btwn harmful (toxins) and harmless Specialized Teeth Mutulism (+/+) Both members benefit Commensalism (+/0) One member benefits, other neither helped nor harmed Parasitism (+/-) One member benefits, other is harmed Species diversity = species richness --. Biodiversity Invasive Species threaten biodiversity Biomass = total mass of individ in a population Trophic structure = feeding relationships w/in a community where only 10% of available energy is passed to next trophic level, as seen in food chains and then food webs Dominant species = most biomass in a population Keystone species = not nec abundant, but have significant control over their ecological role Sea otter Bottom up Model Nutrients control vegetation herbivores predator # Top down Model Predator # herbivores vegetation nutrients Disturbance Moderate levels of disturbance can foster higher species diversity than can low or high levels of disturbance Ecological succession Facilitation & Inhibition (early arrivals facilitate appearance of later arrivals / early arrivals may inhibit later colonization of later arrivals) Primary No soil exists (after fire) Secondary Soil remains after a disturbance (melting glaciers) Humans Species richness declines from tropics Polar regions Climatic influences on sp richness through energy and water Geographic size influences sp richness Pathogens in terrestrial and marine comms Human activities influence (swine & avian flu)