Community Ecology Flashcards
Commnity
Totality of all populations of all species inhabiting a particular area at a given time
Species Richness
Number of species seen in a community
Relative Abundance
Represents the percentage each species contributes to the total number of individuals of all species
Species Evenness
Indicates the distribution of species richness
Keystone Species
Black Spruce Coral Beavers American Bison Sea Otters
Food Web Controls
Bottom-up control
Top-down control
Bottom-up Control
Primary producers regulate the populations of higher trophic levels
Top-down Control
Higher trophic levels regulate abundance and productivity of primary producers
Trophic Cascade
Predators regulate herbivore populations, which benefits the productivity and abundance of primary producers
Succession
Gradual or rapid change in species that occupy a given area, with some species invading and becoming more numerous while others decline and disappear
What is succession caused by?
Change in one or more abiotic factors benefitting some species but at hte expense of others
What is the mature stage called (equilibrium point)?
Climax community
Primary succession
Gradual establishment, through a series of stages, of a mature ecosystem in an area previously unoccupied or unchanged by organisms
Secondary Succession
Reestablishment through a series of stages, of a mature ecosystem
Pioneer Species
Organisms that first colonize sites
Types of Succession
Autogenic
Allogenic
Autogenic
Changes brought about by organisms
Allogenic
Changes caused by external factors other than organisms
Succession Mechanisms
Facilitation
Inhibition
Tolerance
Facilitation
Early seccessional species modify the environment so that it becomes more suitable for successive species to invade and grow
Inhibition model
The first species to arrive hold the site against all invaders, they make the site less suitable for both early and late successional species
Tolerance Model
Later successional species are neither inhibited nor aided by species of earlier stages
