42 terms

APES Chapter 6 Vocab

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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.
Exponential growth model
A growth model that estimates a populations future size after a period of time based on the intrinsic growth rate and the number of reproducing individuals currently in the population
Resource Partitioning
In which two species divide a resource based on differences in the species behavior or morphology. In evolutionary terms, when competition reduces the ability of individuals to survive and reproduce, natural selection will favor individuals that overlap less with other species in the resources they use.
Community
Incorporates all of the populations of organisms within a given area.
J-Shaped
The shape of an exponential growth model when graphed.
Predation
The use of one species as a resource by another species
Population ecology
The study of factors that cause populations to increase or decrease over time.
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.
Pathogens
Parasites that cause disease in their host. Include viruses, bacteria, fungi. protists, and worm like organisms called helminths.
Population Size
The total number of individuals within a defined area at a given time.
S-Shaped
As the population size approaches the carrying capacity the population stops growing. When graphed, the logistic model showed an S-Shaped curve
Mutualism
Benefits two interacting species by increasing both species chances of survival or reproduction.
Population density
The numbers of individuals per unit at a given time.
Overshoot
When population becomes larger than the spring carrying capacity.
Commensalism
A type of relationship in which one species benefits but the other is neither harmed nor helped.
Population Distribution
A description of how individuals are distributed with respect to another.
Die-off
Population crash; when the individuals in a population don't have enough food.
Symbiotic
Relationship of two species that live in close association with eachother.
Sex Ratio
The ratio of males to females
K-selected species
Species that have a low intrinsic growth rate, which cause their populations to increase slowly until they reach the carrying capacity of their environment. The abundance of such species is determined by their carrying capacity and their population fluctuations are small. Because carrying capacity is denotes as K in population models, such species are called K-selected species
Keystone Species
Species that plays a role in it's community that is far more important than it's relative abundance might suggest.
Age Structure
A description of how many individuals fit into particular age categories
R-selected species
Don't typically remain near their carrying capacity, but instead exhibit rapid population growth that is often followed by overshoots and die-offs. Tend to be small organisms that reach productive maturity relatively early, reproduce frequently and produce small offspring.
Predator-Mediated Competition
Competition in which a predator is instrumental in reducing the abundance of a superior competitor, allowing inferior competitors to persist.
Density-dependent Factors
A factor that influences an individuals probability of survival and reproduction in a manner that depends on the size of the population
Survivorship Curves
Distinct patterns of survival for a species
Ecosystem Engineers
Species that create of maintain habitat for other species.
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
Corridors
Strips of natural habitat that connect separate populations.
Ecologist Succession
The replacement of one group of species by another group of species over time.
Density-independent Factors
A factor that has the same effect on an individuals probability of survival and the amount of reproduction at any population size.
Community Ecology
The study of interactions, which determine the survival of a species in a habitat
Carrying Capacity
The limit of how many individuals in a population the food supply can sustain.
Metapopulation
A group of spatially distinct populations that are connected by occasional movements of individuals between them
Primary Succession
Occurs in surfaces that are initially devoid of soil, such as an abandoned parking lot, newly exposed rock left behind after a glacial retreat or newly cooled lava.
Secondary Succession
Occurs in areas that have been disturbed but have not lost their soil. Follows an event such as a forest fire or hurricane, that removes vegetation but leaves the soil mostly inntact. Also occurs on abandoned agricultural fields, such as New England farms.
Growth Rate
The number of offspring an individual can produce in a given time period, minus the deaths of the individual or it's offspring an individual can produce in a given time period.
Competition
The struggle of individuals to obtain a limiting resource.
Pioneer Species
Ex. Trees such as aspen and cherry. Called this because of their ability to colonize new areas rapidly and grow well in full sunshine.
Intrinsic Growth Rate
The maximum potential for growth of a population under ideal conditions with unlimited resources.
Competitive Exclusive Principle
Two species competing for the same limiting resource cannot coexist.
Theory of Island Biogeography
Demonstrates the dual importance of habitat size and distance in determining species richness.