lecture8 - Population growth 8 J uly 1 Population a group...

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Unformatted text preview: Population growth 8 J uly 1 Population a group of conspecific individuals living in a particular place Population size number of individuals in the population Population density number of individuals per unit area in the population How to measure population density (or size): How to measure population density (or size): Absolute density actual number of individuals per unit area Total counts (humans, trees, sessile animals) Sampling methods Density = mean number of individuals area of quadrat Time 1 capture and mark a sample of individuals Time 2 capture a sample of individuals 5 20 16 No. of marked individuals captured at Time 2 (C) Total no. of individuals captured at Time 2 (B) No. individuals captured and marked at Time 1 (A) C B = A N Estimates the population size = N 5 20 = 16 N N = 64 Crucial assumptions: Marked and unmarked animals are captured randomly No loss or gain of individuals between times 1 and 2 Relative density index of population density relative to others using the same method (used to compare different populations or changes within a population over time) traps, fecal pellets, artifacts, vocalizations, questionnaires traps, fecal pellets, artifacts, vocalizations, questionnaires Population growth 8 July 2 Density is negatively correlated with body weight for mammals and birds Population density decreases with body size Demography study of the vital statistics of a population and how they vary with age Life table list of the vital statistics of a population Cohort a group of individuals in a population born about the same time Survivorship (lx) proportion of individuals born that survives to age x 6 20 5 40 4 40 3 60 2 80 1 100 l x No. surviving * Age Class * At beginning of the age class Hypothetical mammal Population growth 8 July 3 Survivorship Curves amphibians, fish, invertebrates, plants 3 birds, small mammals, reptiles 2 large mammals 1 Examples Type Age-Specific Fecundity (m x ) average number of offspring produced by an individual of age x 0.2 0.4 0.4 0.6 0.8 1.0 l x m x 6 20 5 40 4 40 3 60 2 80 1 100 No. surviving Age Class Net Reproductive Rate (R o ) average number of offspring produced by an individual during its entire lifetime (population growth rate per generation)...
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This note was uploaded on 01/06/2010 for the course EVE 101 taught by Professor Strong,d during the Spring '08 term at UC Davis.

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lecture8 - Population growth 8 J uly 1 Population a group...

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