| A | B |
|---|
| species richness | the number of species a community contains |
| relative abundance | differences of abundance of species in a community |
| individualistic hypothesis | the concept thata plant community is a chance assemblge of species found in the same area simply because they happen to have similar biotic requirements |
| interactive hypothesis | the concept that a community is an assemblage of closely linked species, locked into association by mandatory biotic interactions that cause the community to function as an intergrated unit, a short super-organism |
| rivet model | the concept that many or most of the species in a community are associated tightly with other species in a web of life |
| redundancy model | the concept that most of the species in a community are not tightly coupled with one anothee, meaing that the web of life is very loose |
| interspecific interactions | relationships between the species of a community |
| interspecific competition | competition for resource between plabts, between animals, or between decomposers when resources are in short supply |
| competitive exclusion principle | the concept that when populations of 2 similar species compete for the same limited resources, one population will use the resources more efficiently and have a reproductive advantage that will eventually lead to elimination of the other population |
| ecological niche | the sum total of a species' use of the biotic and abiotic resources in its enviornment |
| resource partitioning | the differentiation of niches that enables similar species to coexist in a community |
| character displacement | the tendancy for characteristics to be more divergant in sympatric populations of two species than in allopatric populations of the same two species |
| predation | an interaction between species in which one species , the predator, eats the other, the prey |
| herbivory | the consumption of plant material by a herbivore |
| parasitism | an interaction between two organisms where one organism benefits to the expense of the host who is harmed |
| cryptic coloration | camoflage;a passive defense that makes potential prey difficult to spot against its background |
| aposematic coloration | warning coloration |
| batesian mimicry | a palatable or harmless species mimics an unpalatable or harmful model |
| mullerian mimicry | two or more unpalatable species resemble each other (example: bees, wasps, and yellow jackets) |
| parasite | an organism that aborbs nutrients from the body fluids of living hosts |
| host | the larger participantin a symbiotic relationship, serving as home and feeding ground to the symbiont |
| endoparasitism | parasites that live within their host |
| ectoparasitism | parasites that feed on the external surface of their host |
| parasitoidism | insects lay egges on the living host; larvae eat feed on the body of the host eventually killing it |
| mutualism | an interspecific interaction where both species benefit |
| commensalism | an interaction between species that only benefits one species involved |
| coevolution | refers to reciprocal evolutionary adaptations of two interacting species |
| trophic structure | the dynamics and structure of a community depend on the feeding relationships between organisms |
| food chain | the transfer of food energy from its source in plants and other photosynthetic organisms through herbivores to carnivoresand eventually decomposers |
| trophic levels | the four or five links of a food chain |
| food web | the elaborate, interconnected feeding relationships in an ecosystem |
| energetic hypothesis | suggests that the length of a food chain is limited by the inefficiency of energy along the food chain |
| dynamic stability hypothesis | the idea that long food chains are less stable than short chains |
| dominant species | those species in a community that have the highest abundance or highest biomass |
| biomass | the sum of weight of all individuals in a population |
| keystone species | exert stong control on community structure not so much by numerical might as by their ecological roles, or niches |
| bottom-up model | a model of community organization in which mineral nutrients control community organization because nutrients control plant numbers, which in turn control herbivore numbers, which in turn control predator numbers. |
| top-down model | a model of community organization in which predation controls community organization because predators control herbivores, which in turn control plants, which in turn control nutreint levels; also called the trophic cascade model |
| stability | the tendancy of a community to reach and maintain an equlibrium in the face of disturbances |
| nonequlibrum model | communities are seen as constantly changing after being buffeted by disturbances |
| ecological succession | the process where transitions of species composition over ecological time |
| primary succession | the process of ecological succession if it begins in a virtually lifeless area where soil has not yet formed |
| secondary succession | occurs where an existing community has been cleared by some disturbance that leaves the soil intact |
| biodiversity | species diversity |
| heterogeneity | considers both diversity factors (richness and relative abundance) |
| species-area curve | the biodiversity pattern noting that the larger geographic area of community we sample, the greater the number of species |
