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36 Cards in this Set
- Front
- Back
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population
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group of individuals all of the same species living in the same area
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ecosystem
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describes the inter-relationships between the organisms in a community and their physical environment
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habitat
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type of place where an organisms usually lives
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community
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a group of populations living in the same area
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biosphere
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composed of all the regions of the earth that contain living things
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niche
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all the biotic and abiotic resources in the environment used by the organism
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size
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size of a population (N); the total number of individuals in the population
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density
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total number of individuals per area or volume occupied
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dispersion
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how individuals in a population are distributed
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age structure
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description of the abundance of individuals of each age
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survivorship curves
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describes how mortality of individuals in a species varies during their lifetimes
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survivorship curves type I
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describes species in which most individuals survie to middle age. After, mortality is high.
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survivorship curves type II
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describes organisms in which the length of survivorship is random; likelihood of death is the same at any age
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survivorship curve type III
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describes species in which the most die young, with only a relative few surviving to reproductive age and beyond
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biotic potential
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maximum growth rate of a population under ideal conditions, with unlimited resources and w/o any growth restrictions
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carrying capacity
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maximum number of individuals of a population that can be sustained by a particular habitat
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limiting factors
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elements that prevent a population from attaining its biotic potential
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density-dependent
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those agents whose limiting factor effect becomes more intense as the population density increases
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density-independent
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factors occur independently of the density of the population
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reproductive rate (growth rate)
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r in the equation
r = (births-deaths)/N |
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intrinsic rate
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when the reproductive rate, r, is maximum (biotic potential)
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exponential growth
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occurs whenever the reproductive rate is greater than zero
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J-shaped
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r-selected species
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logistic growth
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occurs when the limiting factors restrict the size of the population to the carrying capacity of the habitat
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s-shaped (sigmoid)
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plot of logistic growth
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population cycles
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fluctuations in population size in response to varying effects of limiting factors
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r-selected species
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exhibits rapid growth (j-shaped curve)
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opportunistic species
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quickly invade a habitat, reproduce, and then die. offspring are many, small, and mature fast w/ little care (grasses, insects)
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k-selected species
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population size remains relatively constant (at carrying capacity k)
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interspecific competition
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competition between different species
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competition exclusion principle (Gause's principle)
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two species compete for exactly the same resources, one is likely to be more successful; eventually one is eliminated
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resource partitioning
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by pursuing slightly different resources or securing their resources in slightly different ways, individuals minimize competition and maximize success
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character displacement (niche shift)
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selection os certain characteristics reduces competition w/ individuals in other partitions and leads to a divergence of features
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realized niche
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when competitors are present, one of both species can coexist by occupying this niche where niche overlap is absent
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fundamental niche
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niche an organism occupies in the absence of competing species
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niche overlap
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they compete for the same resources
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