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POPULATION ECOLOGY

POPULATION ECOLOGY. Density-number/unit of area or volume Census Estimate by indirect indicators Mark-recapture method. Dispersal-spacing among individuals Clumped-humans Uniform-penguin rookery Random-not common in nature. Characteristics of Populations. Demography.

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POPULATION ECOLOGY

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  1. POPULATION ECOLOGY

  2. Density-number/unit of area or volume Census Estimate by indirect indicators Mark-recapture method Dispersal-spacing among individuals Clumped-humans Uniform-penguin rookery Random-not common in nature Characteristics of Populations

  3. Demography • Study of vital statistics • Age structure • Birth rate (fecundity) and death rate • Generation time • Sex ratio • Survivorship curves

  4. SURVIVORSHIP CURVE-TRACKS • Which curve would fit an organism that cares for its young and reproduces relatively late in life? • Which curve would be typical of an organism that experiences high predation as small individuals but when they are adults are more able to avoid most predators? • Which curve might best fit rodents that die in numbers at all ages? • TYPE I • Low death rates early in life • TYPE II • Death rate constant • TYPE III • High death rates early on in life

  5. POPULATION GROWTH • EXPONENTIAL ( r ) • Very rapid • Rate of growth constantly increases • Assumes unlimited resources are available

  6. r-selection • Populations that maximize (r), the intrinsic rate of increase • Individuals mature early, produce large numbers of offspring at a time • Maximize reproductive success in uncrowded, unpredictable environments • Many insect and weed populations

  7. K-Selection • Common in populations that live at densities close to the carrying capacity (K) of their environment • Maturity and reproduction at a later age • Production fo few, well-cared for young

  8. Population Growth Models • Exponential growth-describes an idealized population in an unlimited environment • Logistic model-incorporates the concept of carrying capacity; assumes rate of growth slows as it approaches the carrying capacity (K) • Two types of populations: K-selected (few offspring), r-selected (high reproductive rate)

  9. SELF-ASSESSMENT • Directions: ANSWER the questions and then justify WHY that is the CORRECT answer. • The observation that members of a population are uniformly distributed suggests that • The size of the area occupied by the population is increasing. • Resources are distributed unevenly. • The members of the population are competing for access to a resource. • The members of the population are neither attracted to nor repelled by one another. • The density of the population is low. • Population ecologists follow the fate of same-age cohorts to • Determine a population’s carrying capacity. • Determine if a population is regulated by density-dependent processes • Determine the birth & death rate of each group in a population • Determine the actors that regulate the size of a population • Determine if a population’s growth is cyclic. • Which of the following statements about human population in industrialized countries is INCORRECT? • Average family size is relatively small. • The population has undergone the demographic transition. • Life history is r-selected. • The survivorship curve is Type I. • Age distribution is relatively uniform.

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