individual
The simplest level is the ___________, a single organism.
species, area, time
A population is composed of al individuals that belong to the same ________ and live in a given _________ at a particular _______.
populations, area
A community incorporates all the ___________ within a given _______.
ecosystem
Communities exist within an ________, which is all the biotic and biotic components in a particular location.
biosphere
The largest and most complex system environmental scientists study is the __________.
density-independent factors
factors that have the same effect on an individual's probability of survival and the amount of reproduction at any population size
sex ratio
the ratio of males to females
density-dependent factors
factors that influence an individual's probability of survival and reproduction in a manner that depends on the size of the population
population ecology
the study of factors that cause populations to increase or decrease
carrying capacity (K)
the limit of how many individuals in a population the food supply can sustain
age structure
a description of how many individuals fit into particular age categories
population distribution
a description of how individuals are distributed with respect to one another
limiting resource
a resource that a population cannot live without and occurs in quantities lower than the population would require to increase in size
population density
the number of individuals per unit area (or volume) at a given time
population size
the number of individuals within a defined area at a given time
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TYPE "ok" OR "what": The levels of complexity from individual to biosphere are: individual, population, community, ecosystem, and biosphere
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TYPE "ok" OR "what": Basic population characteristics include size, density, sex ratio, and age structure
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TYPE "ok" OR "what": The three types of population distributions are random, uniform, and clumped
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TYPE "ok" OR "what": Density-dependent and density-independent factors can influence population size
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TYPE "ok" OR "what": The different growth models used to explain changes in population size are exponential and logistic
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TYPE "ok" OR "what": Some populations experience cycles of overshoots and die-offs that oscillate around the carrying capacity
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TYPE "ok" OR "what": Predators play an important role in limiting population growth
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TYPE "ok" OR "what": The two reproductive strategies an organism has are classified as K-selected or R-selected
exponential growth model
a growth rate 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
corridors
strips of natural habitat that connect separated populations
metapopulation
groups of spatially distinct populations that are connected by occasional movements of individuals between them
growth rate
the number of offspring an individual can produce in a given time period, minus the deaths of the individual or any of its offspring during the same period
die-off
a rapid decline in a population due to death
R-selected species
species that have a high intrinsic growth rate, which often leads to population overshoots and die-offs
J-shaped curve
the curve of the exponential growth model when graphed
S-shaped curve
the shape of the logistic growth model when graphed
K-selected species
species with low intrinsic growth rates that cause the population to increase slowly until it reaches carrying capacity
intrinsic growth rate
the maximum potential for growth of a population under ideal conditions with unlimited resources
survivorship curves
graphs that represent the distinct patterns of species survival as a function of age
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
overshoot
when a population becomes larger that the environment's carrying capacity
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TYPE "ok" OR "what": Species interact together in four ways--completion, predation, mutualism, and commensalism
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TYPE "ok" OR "what": Sometimes the loss of one species can have a major effect on the entire community
keystone species
species that are far more important in their community than their relative abundance might suggest
predation
the use of one species as a resource by another species
ecosystem-engineers
keystone species that create or maintain habitat for other species
community ecology
the study of interactions between species
parasites
predators that live in or on the organism that it consumes
resource partitioning
a situation in which two species divide a resource, based on differences in their behavior or morphology
mutualism
an interaction between species that increases the chances of survival or reproduction for both species
competition
the struggle of individuals to obtain a limiting resource
predator-mediated competition
competition in which a predator is instrumental in reducing the abundance of a superior competitor, allowing inferior competitors to persist
competitive exclusion principle
the principle stating that two species competing for the same limiting resource cannot coexist
herbivores
predators that consume plants as prey
commensalism
a relationship between species in which one species benefits and the other species is neither harmed nor helped
pathogen
illness-causing bacterium, virus, or parasite
true predators
predators that typically kill their prey and consume most of what they kill.
parasitoids
organisms that lay eggs inside other organisms
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TYPE "ok" OR "what": As communities change over time, they undergo either primary or secondary succession.
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
ecological succession
the replacement of one group of species by another group of species over time
pioneer species
a species that can colonize new areas rapidly
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TYPE "ok" OR "what": Latitude, time, habitat size, and distance from other communities help determine the number and types of species present in a biome
habitat size, distance
The theory of island biogeography states the importance of both ________ ________ and ____________ in determining species richness