47 terms

APES Chapter 6 Review

After reading this chapter you should be able to: - list the levels of complexity found in the natural world. - contrast the ways in which density-dependent and density-independent factors affect population size. - explain growth models, reproductive strategies, survivorship curves, and metapopulations. - describe species interactions and the roles of keystone species. - discuss the process of ecological succession. - explain how latitude, time, area, and distance affect the species richness of…
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Terms in this set (...)

levels of complexity
Individual -> Population -> Community -> Ecosystem -> Bisophere
population
The individuals that belong to the same species and live in a given area at a given time.
community
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 (N)
The total number of individuals within a defined area at a given time.
population density
The number of individuals per unit area at a given time.
population distribution
A description of how individuals are distributed with respect to one another. Populations in nature distribute themselves in three ways: random, uniform, and clumped distribution.
sex ratio
The ratio of males to females.
age structure
A description of how many individuals fit into particular age categories.
density-dependent factor
A factor that influences an individual's probability of survival and reproduction in a manner that depends on the size of the population. Example: amount of available food.
limiting resource
A resource that a population cannot live without and that occurs in quantities lower than the population would require to increase in size.
carrying capacity (K)
The limit of how many individuals in a population the food supply can sustain.
density-independent factor
A factor that has the same effect on an individual's probability of survival and the amount of reproduction at any population size. Examples: tornadoes, hurricanes, floods, fires, volcanic eruptions, and other climatic events.
growth rate
The number of offspring an individual can produce in a given time period, minus the death of the individual or any of its offspring during the same period.
intrinsic growth rate (r)
The maximum potential for growth of a population under ideal conditions with unlimited resources.
exponential growth model
(Nt = N0 ert) A growth model that estimates a population's future size (Nt) after a period of time (t), based on the intrinsic growth rate (r) and the number of reproducing individuals currently in the population (N0).
J-shaped curve
The curve of the exponential growth model when graphed.
logistic growth model
A growth model that describes a population whose growth is initially exponential, but slows as the population approaches the carrying capacity of the environment.
S-shaped curve
The shape of the logistic growth model when graphed.
overshoot
When a population becomes larger than the environment's carrying capacity.
die-off
A rapid decline in a population due to death.
K-selected species
A species with a low intrinsic growth rate that causes the population to increase slowly until it reaches carrying capacity.
r-selected species
A species that has a high intrinsic growth rate, which often leads to population overshoots and die-offs.
survivorship curve
A graph that represents the distinct patterns of species survival as a function of age.
corridor
A strip of natural habitat that connects separated populations.
metapopulation
A group of spatially distinct populations that are connected by occasional movements of individuals between them.
community ecology
The study of interactions between species.
competition
The struggle of individuals to obtain a limiting resource.
competitive exclusion principle
The principle stating that two species competing for the same limiting resource cannot coexist.
resource partitioning
A situation in which two species divide a resource, based on differences in their behavior or morphology.
predation
The use of one species as a resource by another species.
true predator
A predator that typically kills its prey and consumes most of what it kills.
herbivore
A predator that consumes plants as prey.
parasite
A predator that lives on or in the organism it consumes.
pathogen
An illness-causing bacterium, virus, or parasite.
parasitoid
An organism that lays eggs inside other organisms.
mutualism
An interaction between species that increases the chances of survival or reproduction for both species.
commensalism
A relationship between species in which one species benefits and the other species is neither harmed nor helped.
symbiotic
A relationship of two species that live in association with each other.
keystone species
A species that is far more important in its community that in its relative abundance might suggest.
predator-mediated competition
Competition in which a predator is instrumental in reducing the abundance of a superior competitor, allowing inferior competitors to persist.
ecosystem engineer
A keystone species that creates or maintains habitat for other species.
ecological succession
The replacement of one group of species by another group of species over time.
primary succession
Ecological succession occurring on surfaces that are initially devoid of soil.
secondary succession
The succession of plant life that occurs in areas that have been disturbed but have not lost their soil.
pioneer species
A species that can colonize new areas rapidly.
theory of island biogeography
A theory that demonstrates the dual importance of habitat size and distance in determining species richness.