Population ecology

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Population ecology

  1. 1. Community Ecology Populations
  2. 2. Patterns of Human Population Growth <ul><li>Age structure diagrams </li></ul><ul><ul><li>Population profiles </li></ul></ul><ul><ul><li>Graph the numbers of people in different age groups in the population </li></ul></ul>
  3. 3. Male Female Rapid Growth Guatemala Nigeria Saudi Arabia Slow Growth United States Australia Canada Male Female Ages 0-14 Ages 15-44 Ages 45-85+ © 2004 Brooks/Cole – Thomson Learning
  4. 4. Zero Growth Spain Austria Greece Negative Growth Germany Bulgaria Sweden Male Female Male Female Ages 0-14 Ages 15-44 Ages 45-85+ © 2004 Brooks/Cole – Thomson Learning
  5. 5. 6 100+ 95-99 90-94 85-89 80-84 75-79 70-74 65-69 60-64 55-59 50-54 45-49 40-44 35-39 30-34 25-29 20-24 15-19 10-14 5-9 0-4 Male Female Percent of population 1900 Age 5 4 3 2 1 0 1 2 3 4 5 6 US Population Growth
  6. 6. 100+ 95-99 90-94 85-89 80-84 75-79 70-74 65-69 60-64 55-59 50-54 45-49 40-44 35-39 30-34 25-29 20-24 15-19 10-14 5-9 0-4 Male Female Percent of population 2000 Age 5 4 3 2 1 0 1 2 3 4 5 100+ 95-99 90-94 85-89 80-84 75-79 70-74 65-69 60-64 55-59 50-54 45-49 40-44 35-39 30-34 25-29 20-24 15-19 10-14 5-9 0-4 Percent of population 2050 Age 4 3 2 1 0 1 2 3 4
  7. 7. Age Age Females Males 1955 20 16 12 8 4 4 8 12 16 20 24 20 16 12 8 4 4 8 12 16 20 24 Females Males 1985 Millions Millions © 2004 Brooks/Cole – Thomson Learning 1955
  8. 8. Age 24 20 16 12 8 4 4 8 12 16 20 20 Females Males Age Females Males 1955 24 20 16 12 8 4 4 8 12 16 20 20 2035 Millions Millions © 2004 Brooks/Cole – Thomson Learning 2015
  9. 9. Changes in a Population <ul><li>3 factors determine population changes </li></ul><ul><ul><li>births </li></ul></ul><ul><ul><li>deaths </li></ul></ul><ul><ul><li>migration </li></ul></ul><ul><ul><ul><li>immigration </li></ul></ul></ul><ul><ul><ul><li>emigration </li></ul></ul></ul>
  10. 10. Human Population Growth <ul><li>J curve growth </li></ul><ul><li>grows at a rate of about 80 million yearly (r=1.3%) </li></ul>
  11. 11. Population Growth Developing countries are expected to account for 97% of the population added from 1950 to 2100
  12. 20. U.S. 310,728,519 World 6,882,190,241
  13. 23. Economic Development Trade-Offs Good News Bad News Global life expectancy doubled since 1950 Life expectancy 11 years less in developing countries than in developed countries Food production ahead of population growth since 1978 Harmful environmental effects of agriculture may limit future food production Infant mortality cut in half since 1955 Air and water pollution down in most developed countries since 1970 Number of people living in poverty dropped 6% since 1990 Infant mortality rate in developing countries over 8 times higher than in developed countries Air and water pollution levels in most developing countries too high Half of world’s people trying to live on less than $3 (U.S.) per day
  14. 24. Ecological Footprint Humanity’s ecological footprint per person exceeds the earth’s biological capacity to replenish renewable resources and absorb waste by about 15%!!!
  15. 25. What is your Footprint? http://www.earthday.net/footprint/flash.html
  16. 26. Survivorship <ul><li>three types of survivorship curves </li></ul><ul><ul><li>late loss (Type I) </li></ul></ul><ul><ul><ul><li>have a high survival rate of the young, live out most of their expected life span and die in old age. </li></ul></ul></ul><ul><ul><li>constant loss (Type II) </li></ul></ul><ul><ul><ul><li>relatively constant death rate throughout their life span - death could be due to hunting or diseases. </li></ul></ul></ul><ul><ul><li>early loss (Type III) </li></ul></ul><ul><ul><ul><li>have many young, most of which die very early in their life. </li></ul></ul></ul>
  17. 28. Population Growth and Regulation <ul><li>carrying capacity (K) </li></ul><ul><li>determined by </li></ul><ul><ul><li>renewable resources like water, nutrients, and light </li></ul></ul><ul><ul><li>nonrenewable resources such as space </li></ul></ul>
  18. 29. <ul><li>Logistic growth: exponential growth when resources are unlimited and slowed growth as species approach carrying capacity of environment. </li></ul><ul><ul><li>Growth curve called an S-curve because of its shape. </li></ul></ul><ul><li>Environmental resistance: factors that tend to reduce population growth rates. </li></ul>
  19. 30. Strategies of Population Growth <ul><li>r-adapted species (adapted for high rates of growth) </li></ul><ul><ul><li>Insects, rodents, marine invertebrates, parasites, and annual plants </li></ul></ul><ul><li>K-adapted species (adapted for living at or near carrying capacity) </li></ul><ul><ul><li>Wolves, elephants, whales, and primates </li></ul></ul>
  20. 31. r- and K-Stratigies Characteristics of contrasting reproductive strategies r-adapted species K-adapted species <ul><li>Short life </li></ul><ul><li>Rapid growth </li></ul><ul><li>Early maturity </li></ul><ul><li>Many small offspring </li></ul><ul><li>Little parental care or protection </li></ul><ul><li>Little investment in individual offspring </li></ul><ul><li>Adapted to unstable environment </li></ul><ul><li>Pioneers, colonizers </li></ul><ul><li>Niche generalists </li></ul><ul><li>Prey </li></ul><ul><li>Regulated mainly by extrinsic factors </li></ul><ul><li>Low trophic level </li></ul><ul><li>Long life </li></ul><ul><li>Slower growth </li></ul><ul><li>Late maturity </li></ul><ul><li>Fewer large offspring </li></ul><ul><li>High parental care and protection </li></ul><ul><li>High investment in individual offspring </li></ul><ul><li>Adapted to stable environment </li></ul><ul><li>Later stages of succession </li></ul><ul><li>Niche specialists </li></ul><ul><li>Predators </li></ul><ul><li>Regulated mainly by intrinsic factors </li></ul><ul><li>High trophic level </li></ul>
  21. 32. Community Structure <ul><li>Individuals within a population can be distributed randomly, clumped together, or in highly regular patterns. </li></ul>
  22. 34. Communities in Transition <ul><li>Ecological succession: process by which organisms occupy a site and gradually change environmental conditions by creating soil, shelter, and increasing humidity. </li></ul><ul><ul><li>Primary succession: community begins to develop on a site previously unoccupied by living organisms. </li></ul></ul><ul><ul><li>Secondary succession: existing community is disrupted and a new one develops. </li></ul></ul>

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