Chapter 52: Population Ecology

Population Growth Patterns Type of Growth? Exponential growth “J curve” CH52#6

Population Growth Patterns Some populations of organisms reach a plateau in their growth. This is called their carrying capacity. These populations are said to be growing with logistical growth. “S curve” carrying capacity CH52#6

Carrying capacity – The number of organisms that can be supported by a particular ecosystem *within natural resource limits-without destroying it. *Limiting Factors… CH52#6

Logistical vs. Exponential Population Growth Patterns What is the carrying capacity of the population on the right? About how many days did it take for the population to reach carrying capacity? Which of the following is probably NOT a reason the population reached and maintained a plateau? a. limits in food supply b. competition with other species c. competition for space d. a major storm

Logistical vs. Exponential Population Growth Patterns What is the carrying capacity of the population on the right? around 135 individuals About how many days did it take for the population to reach carrying capacity? about 80 days Which of the following is probably NOT a reason the population reached and maintained a plateau? a. limits in food supply b. competition with other species c. competition for space d. a major storm would probably not cause a population to maintain its size

Pair, Share, Explain A population increase in which the population "overshoots" the carrying capacity, K, and then crashes precipitously. Note that after the crash the population rebounds somewhat and approaches a new stable size (dN/dt = 0). Note that the carrying capacity has also changed. In the case of the Kaibab deer, this would represent irreversible (or at least very long term) changes in the amount of food available.

“r”, “K” Strategist general characteristics Survivorship Curves CH52

“r” vs “K” Strategists Survivorship curves

Additional Math practice Population Dynamics… Additional Math practice Population Web Site http://ats.doit.wisc.edu/biology/ec/pd/pd.htm

...the Math… N = Population SIze dN = Change in Population Size dt = Change in Time; generation r = 1.0 = BR – DR (2-1 in this case)

N = Population SIze dN = Change in Population Size dt = Change in Time; generation r = 1.0 = BR – DR (2-1 in this case) 1,500 = ? *N small compared to K- Max rate of Increase *N large/K limiting, Rate of increase is small (K-N/K is close to zero) SEE PP- Logistical-Exponential Lesson

Population Dynamics Birth rate/Death rate United States 14.1/8.7 Australia 12.7/7.3 Iraq 34.2/6.0 Japan 10.0/8.5 Italy 8.9/10.1 Russia 9.7/13.9 Other Factors? Migration: Emigration,Immigration Why?….for people… Life Expectancy,Health Care,Sanitation Economics,Quality of Life,Education

Density dependent vs independent factors Density Dependent Factors: related to the density of the population. (disease, predation, competition) Density Independent Factors: Not related to population size (killing frost, severe blizzard, hurricane, etc) CH52#6

Three Patterns of Population Growth Causes?

Census Bureau http://www.census.gov/population/international/data/ International Data China Single Birth Policy When Instituted?

1978: single birth policy: China