L13 population ecology

L13 population ecology - BILD 3 July 14, 2010 ECOLOGY...

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BILD 3 July 14, 2010 Woodruff: population ecology 1 ECOLOGY (Ernst Haekel, 1865) oikos – house logos – study of Scientific study of an organism or group of organisms in relation to their environment Structural organisms Functional relations & Evolutionary of environment Environment : sum of the substances and forces external to the organism that influence the organism. LEVELS OF INTEREST INDIVIDUAL BIOTIC ORGANISM ENVIRONMENT ABIOTIC POPULATION One or more individuals of the same species co- occurring in time and space. The unit of reproduction and evolution COMMUNITIES, BIOMES & ECOSYSTEMS Associations of species linked by energy flow and resource cycles LEVELS OF INTEREST INDIVIDUAL BIOTIC ORGANISM ENVIRONMENT ABIOTIC HABITAT : “area or address” Place where the organism/species normally lives NICHE : “Occupation” All components of the environment with which the organism/species typically interacts. (A subset of the environment) Population ecology is the study of populations in relation to the environment, including dynamic environmental and biological influences on population density, dispersion, distribution, age structure, demography & size. Density is the number of individuals per unit area or volume. Determining the density of natural populations is difficult. In most cases, it is impractical or impossible to count all individuals in a population. Density is the result of an interplay between processes that add individuals to a population and those that remove individuals. Fig. 53-3 Births Births and immigration add individuals to a population. Immigration Deaths and emigration remove individuals from a population. Deaths Emigration I – IMMIGRATION E – EMIGRATION B – BIRTHS D – DEATHS Patterns of Dispersion Dispersion is the pattern of spacing among individuals within the boundaries of the population Environmental and social factors influence spacing of individuals in a population In a clumped dispersion, individuals aggregate in patches A uniform dispersion is one in which individuals are evenly distributed In a random dispersion, the position of each individual is independent of other individuals
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BILD 3 July 14, 2010 Woodruff: population ecology 2 Demography is the study of the vital statistics of a population and how they change over time Death rates and birth rates are of particular interest to demographers Projections are derived from: Life tables: age-specific birth and death rates Age structure pyramids Sex ratios Survivorship curves Fertility schedule (reproductive table) DEMOGRAPHY Life Tables • A life table is an age-specific summary of the survival pattern of a population • It is best made by following the fate of a cohort • The life table of Belding’s ground squirrels reveals many things about this population Table 53-1 Survivorship Curves • A survivorship curve is a graphic way of
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This note was uploaded on 07/28/2010 for the course BIOLOGY BILD 3 taught by Professor Davidwoodruff during the Summer '10 term at San Diego.

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L13 population ecology - BILD 3 July 14, 2010 ECOLOGY...

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