1. Population Notes And Human Population Trends

2. Population- group of similar individuals (species) living in one area Population- group of similar individuals (species) living in one area –The size of a population will change over time

3. Population Determiners Natality (+)- birth rate Natality (+)- birth rate Mortality (-)- death rate Mortality (-)- death rate - both of these are rates within a pop. in a community Immigration (+)- the arrival of individuals into a community from somewhere else Immigration (+)- the arrival of individuals into a community from somewhere else Emigration (-)- the departure of indiv from a community Emigration (-)- the departure of indiv from a community

4. Open v. Closed Populations Open population- a pop. (or community) where immigration and emigration occur freely; ex- the state NC Open population- a pop. (or community) where immigration and emigration occur freely; ex- the state NC Closed Population- a pop. in which individuals are not allowed to leave and enter freely. This is usually due to some physical barrier; ex- Galapagos Islands Closed Population- a pop. in which individuals are not allowed to leave and enter freely. This is usually due to some physical barrier; ex- Galapagos Islands

5. Example (do not copy) An open population of Elk in the Comanche River Basin of Wyoming has a natality rate of 12.4 elk/year and a mortality rate of 10.6 elk/yr. This population of elk emigrates to a hanging valley to forage for vegetation in the winter. At this time, a herd of 9 elk immigrates into the Comanche River Basin population from the Shoshone River Basin elk population. An open population of Elk in the Comanche River Basin of Wyoming has a natality rate of 12.4 elk/year and a mortality rate of 10.6 elk/yr. This population of elk emigrates to a hanging valley to forage for vegetation in the winter. At this time, a herd of 9 elk immigrates into the Comanche River Basin population from the Shoshone River Basin elk population.

6. Factors that Affect Pop. Biotic Potential- the highest possible rate of reproduction under ideal conditions Biotic Potential- the highest possible rate of reproduction under ideal conditions Limiting Factors- circumstances that keep org. from reaching biotic potential Limiting Factors- circumstances that keep org. from reaching biotic potential

7. Limiting Factors Density DependentDensity Independent Limiting Factors (related)(individual) shortage of food* temperature, drought, floods, volcanic eruptions, natural disasters lack of space*, disease*, predators*, parasites*oxygen supply * tied to population size * tied to population size

8. Carrying Capacity The greatest number of individuals a community can support The greatest number of individuals a community can support –Can change as conditions (biotic/abiotic) change –When a community reaches c.c. natality and mortality are approximately equal

9. Homeostasis When a pop is in balance with all the abiotic and biotic factors that influence it When a pop is in balance with all the abiotic and biotic factors that influence it

10. Population Graphs Populations of a species can follow one of two basic graph shapes: J or S curves. Populations of a species can follow one of two basic graph shapes: J or S curves.

11. J-Curve Features: Population growth starts slow and then speeds up (shows exponential growth) As population increases, rate of growth increases * Population will continue to grow exponentially as long as there are no limiting factors Most populations cannot maintain a J-curve forever…why not?

12. J-Curve Examples Duck Weed Bacteria Cancer Cells

13. S-Curve Population growth starts slow, speeds up, but hits a limit (Carrying Capacity) and balances out. Population growth starts slow, speeds up, but hits a limit (Carrying Capacity) and balances out. More realistic because, populations can’t grow forever due to limiting factors. More realistic because, populations can’t grow forever due to limiting factors. Shows Logistic Growth Shows Logistic Growth. Limiting factors slow or control the population (Examples: predators, space, shelter, food, disease). Carrying Capacity: the number of individuals of a species an environment can support without becoming harmed.

14. Slow-life historyRapid-life history Slow-life historyRapid-life history *reproduce slowly; long time to mature* reproduce quickly; quick to mature * few offspring in a lifetime* many offspring in a lifetime * long life span* short life span * large bodies* small bodies * live in a stable environment* live in unpredictable/harsh envir. humans, elephants, pandas, etc.* bacteria, flies, mosquitoes, etc. humans, elephants, pandas, etc.* bacteria, flies, mosquitoes, etc. *good for scientific experiments *good for scientific experiments Life History Patterns

15. I. Why is human population growth an environmental problem? A.Causes of human population growth 1. Agricultural Revolution – people settle into communities and more people were needed for division of labor; more reliable food supply can support a larger population. 2. Industrial Revolution – In the early 20th century technological advancements led to improvements in medicine and sanitation allowing for an increased birth rate and decreased death rate. 3. Urbanization (development of cities) leads to economic and social development which influences human population growth in an area.

16. I. Why is human population growth an environmental problem?

17. Industrial Revolution

18. Human Population Density What problems do heavily populated areas have environmentally?

19. Population Pyramids

20. What can you tell about this country based on its age structure graph? What can you tell about this country based on its age structure graph? Wide base = rapid growth Wide base = rapid growth Skinny top = poor health care Skinny top = poor health care

21.  What can you tell about this country based on its age structure graph?  Base not much wider than middle = slow growth  Balanced fairly evenly throughout ages = good health care  # of females at top = females have longer life expectancy

22.  What can you tell about this country based on its age structure graph?  Base smaller than middle = population decline  Balanced fairly evenly throughout age groups = good health care  # females at top = live longer

23. Human Population Graphs

24. Copy graphs on overhead Copy graphs on overhead