43 terms

Environmental Science for AP - Friedland and Relyea Chapter 6

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population
composed of all individuals that belong to the same species and live in a given area at a particular time
community
incorporates all of the populations of organisms within a given area
population ecology
the study of factors that cause populations to increase or decrease
population size
the total number of individuals within a defined area at a given time
population density
the number of individuals per unit area (or volume for aquatic organisms) at a given time
population distriution
a description of how individuals are distributed with respect to one another
sex ration
the ratio of males to females
age structure
a description of how many individuals fit into particular age categories
density-dependent factors
influences an individual's probability of survival and reproduction in a manner that depends on the size of the population
limiting resource
a resource that a population cannot live without and which occurs in quantities lower than the population would require to increase in size
carrying capacity; k
population growth slowed as population size increased because there was a limit to how many individuals the food supply could sustain
Density-independent factors
have the same effect on an individuals probability of survival and amount of reproduction at any population size
growth rate
the number of offspring an individual can produce in a given time period, minus the deaths of the individual or offspring during the same period
intrinsic growth rate; r
under ideal conditions, with unlimited resources available, every population has a particular maximum potential for growth
exponential growth model
tells us that, under ideal conditions, the future size of the population depends on the current size of the population, the intrinsic rate of the population, and the amount of time over which the population grows
logistic growth model
describes a population whose growth is initially exponential, but slows as the population approaches the carrying capacity of the environment
overshoot
when the population becomes larger than the spring carrying capacity
Die-off
population crash usually experienced after the overshoot of the carrying capacity
k-selected species
species that have a low intrinsic growth rate, which causes their populations to increase slowly until they reach the carrying capacity of the environment
r-selected species
species that have a high intrinsic growth rate because they reproduce often and produce large numbers of offspring
survivorship curves
graphs of distinct patterns of survival over time
corridors
strips of habitat that connect separated populations that the animal travels across
metapopulations
a group of spatially distinct populations that are connected by occasional movements of individuals between them
community ecology
the study of species interactions, which determine the survival of a species in a habitat
competition
the struggle of individuals to obtain a limiting resource
competitive exclusion principle
states that two species competing for the same limiting resource cannot coexist
resource partitioning
where two species divide a resource based on differences in the species' behavior or morphology
predation
refers to the use of one species as a resource by another species
true predators
typically kill their prey and consume most of what they kill
herbivores
consumes plants as prey
parasites
live on or in the organisms they consume
parasitoids
organisms that lay eggs inside other organims
mutualism
benefits two interacting species by increasing both species' chances of survival or reproduction
commensalism
a type of relationship in which one species benefits but the other is neither harmed nor helped
symbiotic relationship
the relationship of two species that live in close association with each other
keystone species
a species that plays a role in its community
predator-mediated competition
competition in which a predator is instrumental in reducing the abundance of a superior competitor, allowing inferior competitors to persist
ecosystem engineers
species that create or maintain habitat for other species
ecological succession
the predictable replacement of one group of species by another group of species over time
primary succession
occurs on surfaces that are intially devoid of soil
secondary succession
occurs in areas that have been disturbed but have not lost their soil
pioneer species
organisms that have the ability to colonize new areas rapidly and grow well in full sunshine
theory of island biogeography
demonstrates the dual importance of habitat size and distance in determining species richness