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Chapter 52 Population Ecology

Chapter 52 Population Ecology. Census Anyone?. Characteristics of Populations. What is a population? The characteristics of populations are shaped by the interactions between individuals and their environment. Two characteristics of any population are density and spacing.

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Chapter 52 Population Ecology

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  1. Chapter 52 Population Ecology Census Anyone?

  2. Characteristics of Populations • What is a population? • The characteristics of populations are shaped by the interactions between individuals and their environment.

  3. Two characteristics of any population are density and spacing • The density of a population is measured as the number of individuals per unit area. • Difficult to count numbers. • The dispersion of a population is the pattern of spacing among individuals within the geographic boundaries

  4. Patterns of Dispersion

  5. Demographystudies the vital statistics that affect population size. • A life table is an age-specific summary of the survival pattern of a population.

  6. A graphic way of representing the data is a survivorship curve. • A Type I curve shows a low death rate early in life (humans). • The Type II curve shows constant mortality (squirrels). • Type III curve shows a high death rate early in life (oysters).

  7. Big Bang Reproduction • This is also known as semelparity. • repeated reproduction • This is also known as iteroparity. • What factors contribute to the evolution of semelparity and iteroparity?

  8. The cost of reproduction

  9. Limited Resources • Sometimes we see trade-offs between survival and reproduction when resources are limited. • Ex. Red deer show a higher mortality rate in winters following reproductive episodes. • Ex. Variations also occur in seed crop size in plants.

  10. Exponential model describes an population in an unlimited environment • We define a change in population size based on the following verbal equation. Change in Populaion = Births – Deaths Size during time interval

  11. logistic model of population growth incorporates the concept of carrying capacity • Population growth is therefore regulated by carrying capacity, which is the maximum stable population size a particular environment can support.

  12. Why do all populations eventually stop growing? • Density-dependent factors increase their affect on a population as population density increases. • This is a type of negative feedback. • Density-independent factors are unrelated to population density, and there is no feedback to slow population growth.

  13. Density Dependent • Resource limitation • Intraspecific competition • Territory, Predation, and Waste Accumulation.

  14. Density Independent • Disease

  15. Study of moose pop. on Isle Royal

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