Chapter 7

Chapter 7 - Chapter 7: Mortality Population Regulation:...

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Chapter 7: Population Regulation: Growth and Mortality Refers to the study of factors which determine the abundance, distribution, and reduction of species. Ecologists attempt to explain the observance of population cycles and fluctuations, and the underlying causes for the regulation of animal numbers. The basic premise for these fluctuations and limitations is that two processes occur to impact these numbers: NATURAL SELECTION acts on the individual organism and through this natural adaptive process, populations evolve. ARTIFICIAL SELECTION is due to man-caused disturbances that impact populations and result in selection for lesser or greater adaptations than are naturally occurring. EXTINCTION is the inability to adapt (for various reasons). A) FIELD STUDIES AND RESULTANT MANAGEMENT: These efforts seek to identify, describe and then reverse (if possible) those limiting factors identified for particular wildlife populations or species. Wildlife biologists must become proficient with this kind of work. B) ESSENTIAL TERMINOLOGY: 1) POPULATION DENSITY: A certain number of individuals per unit area. 2) NATALITY: The number of births per thousand, per hundred, or per individual per year. 3) MORTALITY: The number of deaths per number of individuals per year (a rate). 4) COHORT: A group of individuals in a population born during a particular time period, such as a year.
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5) FECUNDITY: Potential capability of an organism to produce reproductive units, such as eggs (most emphasis), sperm, or asexual structures. 6) FERTILITY: A measure of reproduction. The measure of eggs that are fertile. 7) PRODUCTION: The number of surviving offspring produced during a specific period of time, usually per year. 8) RECRUITMENT: Increment to a natural population, usually from young animals or plants entering the adult population. 9) DISPERSAL: Movement of individuals into unfamiliar locations: a) Immigration: Movement into a given area. b) Emigration: Movement out of a given area. 10) MIGRATION: Movement by a population on some regular basis (e.g. seasonally or yearly) away from and back to an area. 11) BIOTIC POTENTIAL (BP): The usually theoretical, genetically controlled, upper limit on a population's rate of increase. Also called the intrinsic rate of reproduction (r). When plotted over time, yields a "J" shaped curve. Consider the BP for the house fly (
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This note was uploaded on 02/18/2012 for the course BIO 260 taught by Professor Dannyraymer during the Fall '11 term at BYU.

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Chapter 7 - Chapter 7: Mortality Population Regulation:...

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