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25 Cards in this Set
- Front
- Back
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what is population ecology?
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the study of populations in relation to their environment. explores how biotic and abiotic factors influence the density, distribution, size, and age structure of the population.
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what is a population?
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a group of individuals of a single species living in the same general area. population members rely on the same resources, are influenced by similar environmental factors, and are likely to interact and breed with one another.
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what are the three fundamental characteristics of a population?
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desnity, dispersion, and demographics.
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define "density".
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the number of individuals per unit area or volume.
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define "dispersion".
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the pattern of spacing among individuals within the boundaries of the population.
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what are the three types of dispersion, and which is the most common?
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clumped, uniform, random / clumped
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define "demography".
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the study of the vital statistics of populations and how they change over time.
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what are "life tables"?
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age specific summaries of the survival pattern of a population.
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what is a "cohort"?
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a group of individuals of the same age, followed in order to construct a life table from birth until all are dead.
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what is a "survivorship curve"?
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a plot of the proportion or numbers of a cohort still alive ate each age.
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what are the three general types of survivorship curves?
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Type I: low death rates during early and middle life, then drops sharply as death rates increase for older age groups.
Type II: intermediate, with a constant death rate over the organism's life span. Type III: drops sharply at the start, reflecting very high death rates for the young, but death rates decline for the few individuals that sruvive the early period of die-off. |
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define "reproductive table" ("fertility schedule").
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an age-specific summary of the reproductive rates in a population. constructed by measuring the reproductive output of a cohort from birth until death.
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what are the three basic variables of a life history?
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when reproduction begins, how often the organism reproduces, and how many offspring are produced during each reproductive episode.
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define "big-bang reproduction" / "semelparity".
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when an organism prodoces a large amount of eggs / seeds one time before dying.
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define "iteroparity" or "repeated reproduction".
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when an organism reproduces several times during its life.
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define "zero population growth".
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when the per capita birth and eath rates are equal, balancing each other exactly.
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define "exponential population growth", aka "geometric population growth".
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when a population's members all have access to abundant food aren are free to reproduce at their physiological capacity. under these conditions, the per capita rate of increase may assume the maximum rate for the species.
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define "carrying capacity", symbolised as K.
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the maximum population size that a particular environment can sustain.
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define "logistic population growth".
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the per capita rate of increase approaches zero as the carrying capacity is reached.
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define "K-selection", aka "desnsity dependent selection".
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selection for life history traits that are sensitive to population density.
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define "r-selection", aka "density independent selection".
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selection for life history tratis that maximise reproductive success in uncrowded environments.
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what does "desnity independent" mean?
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a birth rate or death rate that does not change with population density.
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what does "density dependent" mean?
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a death rate that rises as population density rises or a birth rate that falls with rising density.
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what is "population dynamics"?
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focuses on the complex interactions between biotic and abiotic factors that cause varation in the size of populations.
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what is a "metapopulation"?
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when a number of local populations are linked.
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