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APES Ch. 6 Vocab

Population and Community Ecology - AP Environmental Science, Chapter 6

Population ecology The study of factors that cause populations to increase or decrease
Population size The number of individuals within a defined area at a given time
Population density The number of individuals per unit of area (or volume) at a given time (clustered or dispersed)
Population distribution A description of how individuals are distributed with respect to each other (random, uniform, or clumped)
Sex ratio The ratio of males to females
Age structure How many individuals fit into particular age categories
Density-dependent factors Factors that influence an individual's probability of survival/reproduction in a manner that depends on the size of the population
Limiting resource A resource that a population cannot live without that occurs in quantities lower than what is required for the population to increase in size
Carrying capacity (K) The limit of how many individuals in a population the food supply can sustain
Density-independent factors Factors that have the same effect on an individual's probability of survival/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 its offspring in the same time period
Intrinsic growth rate The maximum potential for growth in a population under ideal conditions and with unlimited resources
Exponential growth model A growth model that estimates a population's future size after a period of time, based on the intrinsic growth rate and the number of reproducing individuals currently in the population
J-shaped curve The curve of an 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
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 population due to health
K-selected species Species with low intrinsic growth rates that cause the population to increase slowly until it reaches carrying capacity
r-selected species Species that have high intrinsic growth rates, which often leads to population overshoots and die-offs
Survivorship curves Graphs that represent the patterns of species survival as a function of age
Corridors Strips of natural habitat that connect separated populations
Metapopulations Groups of spacially distinct populations that are connected by occasional movements of individuals between them
Community ecology The study of interactions between species
Competition The struggle of species to obtain a limiting resource
Competitive exclusion principle 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 if one species as a resource by another species
True predators Predators that kill their prey and consume it
Herbivores Predators that consume plants as prey
Parasites Predators that live on or in the organism they consume
Parasitoids Organisms that lay eggs inside other organisms
Pathogens Illness-causing bacteria, viruses, or parasites
Mutualism An interaction between species that helps both
Commensalism An interaction between species that helps one and doesn't affect the other
Symbiotic relationship A relationship between two species that live in close association with each other
Keystone species Species that are far more important to their communities than their relative abundance may suggest
Predator-mediated competition Competition in which a predator is instrumental in reducing the abundance of a superior competitor, allowing inferior competitors to exist
Ecosystem engineers Keystone species that create of maintain a habitat for other species
Ecological succession The replacement of one group or species by another over time
Primary succession Ecological succession occurring on surfaces that are initially devoid of soil - areas are colonized by organisms such as algae, lichens, and moss, which eventually die and mix with eroded rock to help form soil
Secondary succession The succession of plant life that occurs in areas that have been disturbed but haven't lost their soil
Pioneer species A species that can colonize new areas rapidly
Created by: emilyjane1221