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Population Ecology

Population Ecology. Chapter 52. Population - group of individuals living in same area at same time. Population density - # of individuals per unit area. Population dispersion - arrangement of population in area. Dispersion patterns happen 3 ways. 1 Clumped dispersion - individuals in groups.

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Population Ecology

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  1. Population Ecology Chapter 52

  2. Population - group of individuals living in same area at same time. • Population density - # of individuals per unit area. • Population dispersion - arrangement of population in area.

  3. Dispersion patterns happen 3 ways. • 1Clumped dispersion - individuals in groups. • 2Uniform dispersion – individuals evenly spaced out. • 3Random dispersion - individuals live regardless of where other individuals live.

  4. CLUMPED

  5. UNIFORM

  6. RANDOM

  7. Demography - study of statistics of a population. • Life tables - show summary of specific ages of population and survival rates.

  8. Survivorship curve - can see how many individuals are alive at specific ages.

  9. Reproductive tables - reproductive rates at various ages. • Focus only on females and not males in these tables.

  10. Life history - traits that affect organism’s schedule of reproduction and survival. • 1Big-bang reproduction (produce large number of offspring sometimes followed by the organism’s death) • Known as semelparity.

  11. The agave plant

  12. 2Repeated reproductive episode - organism produces smaller numbers of offspring. • This is also known as iteroparity.

  13. Change in population - # of births minus # of deaths during that same time. • Equation : N/t = r; r= difference between birth and death rates, N= change in population size, and t= change in time.

  14. Limitations on population growth due to resources. • K = carrying capacity. • Carrying capacity – max # of individuals an area can handle based on resources.

  15. Logistic population growth model - incorporates affect of population density on rate of increase. • Carrying capacity cannot be exceeded - graph is S-shaped.

  16. Carrying capacity equals change in population size

  17. Carrying capacity Cannot exceed carrying capacity

  18. Life histories - predict how population will reproduce. • 1K-selection - live and reproduce around K. • 2r-selection - high rates of reproduction, but live in environments where populations are well below K.

  19. 2 factors determine the growth of a population. • 1Density-dependent factors increase their effect as density increases (negative feedback) • 2Density-independent factors - not affected by density increase.

  20. Negative feedback - caused by several different factors. • One - resources (force populations to stop reproducing if conditions are crowded)

  21. As # of planted seeds increase, # reproducing decreases

  22. Competition for resources can force decreased reproduction rates. • Need to defend space can reduce population size. • Predation can decrease the size.

  23. Human population has been steadily growing since 1650. • Zero transition growth # of births = # of deaths. • Only way to steady out population growth.

  24. One of the difficulties with population growth is looking at the distribution of ages. • The problem is that the carrying capacity of Earth has not been determined.

  25. http://www.youtube.com/watch?v=GECJcW2Ifm4

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