1. Populations

3. A population - a group of organisms of the same species in the same area.

4. Population Topics A.What affects population size B.Population growth patterns C.Limits to population growth

5. Page 123 “Analyzing Data” Make a graph showing fruit fly population growth Make a graph showing rabbit population growth

6. A. Population Size Factors that increase population size: Natality (births) Immigration Factors that reduce population size: Mortality Emigration Calculate the Population Size of Akron, CO: In 2010, there were 1400 residents. 92 babies born 47 new people moved there 88 people died 41 people moved away IN 2011: 1410 residents!

7. B. Population Growth Exponential Growth Under ideal conditions with unlimited resources, a population will grow exponentially. Exponential growth occurs when the individuals in a population reproduce at a constant rate. The population becomes larger and larger until it approaches an infinitely large size. Logistic Growth As resources become less available, the growth of a population slows or stops. Logistic growth occurs when a population's growth slows or stops following a period of exponential growth

8. Logistic Growth – 3 phases

9. 1. Exponential Growth Phase – there is unlimited growth of the population due to absence of limiting factors. Examples: germinating annual plants in a new season. a bacterial population during the initial phases of an infection. The population of any species occupying a previously unoccupied habitat

10. Logistic Growth – 3 phases 2. Transitional Phase – limiting factors start influencing the rate of increase of the population. Population is still increasing, but not as rapidly. Examples: Organisms start competing with each other for available resources Survival of the fittest predators move in

11. Logistic Growth – 3 phases 3. Plateau Phase – Population stops increasing, due to limiting factors. The population has reached its carrying capacity. Natality + Immigration = Mortality + Emigration Carrying Capacity – the maximum number of individuals of a species that can be supported by the environment.

12. Think with a partner What are some things that would limit: Plant population growth? Animal population growth?

13. C. Limiting Factors 1.Animals Amount of food available Presence of diseases or parasites Amount of predation Available nesting sites 2.Plants Amount of light available Temperature Amount of water available Space