Population Ecology: Characteristics, Limiting Factors, and Growth

1. Ecology Part 4. Populations Part 5. Communities Part 6. Biodiversity and Conservation

2. Population Ecology: Population Characteristics Population Characteristics • Population Density: • The number of organisms per unit area • Spatial Distribution: • Dispersion: The pattern of spacing a population within an area • 3 main types of dispersion • Clumped • Uniform • Random • The primary cause of dispersion is resource availability

3. Population Ecology: Population Characteristics Population Limiting Factors • Population growth rate • How fast a given population grows • Factors that influence this are: • Natality (____ rate) • Mortality (_____ rate) • Emigration (the number of individuals moving _________ a population) • Immigration (the number of individuals _________ a population) birth death away from moving to

4. Population Ecology: Density-independent factors Population Limiting Factors • Density-independent factors • Factors that limit population size, regardless of population density. • These are usually abiotic factors • They include natural phenomena, such as weather events • Drought, flooding, extreme heat or cold, tornadoes, hurricanes, fires, etc.

5. Population Ecology: Density-dependent factors Population Limiting Factors • Density-dependent factors • Any factor in the environment that depends on the number of members in a population per unit area • Usually biotic factors • These include • Predation • Disease • Parasites • Competition

6. Population Limiting Factors Population Ecology: Population Growth Rate • Population growth models • Limits to exponential growth • Population Density (the number of individuals per unit of land area or water volume) increases as well • Competition follows as nutrients and resources are used up • The limit to population size that a particular environment can support is called carrying capacity (k) • When you’re done writing, put your pens down…

7. Community Ecology: Communities Communities • Review: • A community is a group of interacting populations that occupy the same area at the same time.

8. Community Ecology: Communities Communities • Limiting Factors • Any abiotic or biotic factor that restricts the numbers, reproduction, or distribution of organisms.

9. Community Ecology: Communities Communities • Range of Tolerance • The limits within which an organism can exist.

10. Blog Questions • What are some of the limiting factors in your system? • What is the difference between natality and mortality? • Is temperature a limiting factor and Why? • What is your community in your system?

11. Community Ecology: Ecological Succession Ecological Succession • Ecological Succession • The change in an ecosystem that happens when one community replaces another as a result of changing biotic and abiotic factors

12. Community Ecology: Ecological Succession Ecological Succession • Ecological Succession • Consists of 2 types: • Primary Succession • Secondary Succession

13. Community Ecology: Ecological Succession: Primary Succession Ecological Succession • Ecological Succession: Primary • The establishment of a community in an area of exposed rock that does not have topsoil is called Primary Succession. • It occurs very slowly at first

14. Community Ecology: Ecological Succession: Primary Succession Ecological Succession • Ecological Succession: Primary • The first organisms to arrive are usually lichens or mosses, which are called pioneer species. • They secrete acids that can break down rock • Their dead, decaying organic materials, along with bits of sediment from the rock make up soil.

15. Community Ecology: Ecological Succession: Primary Succession Ecological Succession • Ecological Succession: Primary • Small weedy plants and other organisms become established. • As these organisms die, additional soil is created

16. Community Ecology: Ecological Succession: Primary Succession Ecological Succession • Ecological Succession: Primary • Seeds brought in by animals, water and wind begin to grow in the soil. • Eventually enough soil is present for shrubs and trees to grow.

17. Community Ecology: Ecological Succession: Primary Succession Ecological Succession • Ecological Succession: Primary • The stable, mature community that eventually develops from bare rock is called a climax community.

18. Community Ecology: Ecological Succession: Secondary Succession Ecological Succession • Ecological Succession: Secondary • Disturbances (fire, flood, windstorms) can disrupt a community. • After a disturbance, new species of plants and animals might occupy the habitat.

19. Community Ecology: Ecological Succession: Secondary Succession Ecological Succession • Ecological Succession: Secondary • Pioneer species in secondary succession are usually plants that begin to grow in the disturbed area. • This is much fasterthan primarysuccession

20. Community Ecology: Ecological Succession Ecological Succession • Ecological Succession: End point? • Cannot be predicted • Different rates of growth &human involvementmake it impossible toknow if a true climaxcommunity has beenreached.

21. Biodiversity and Conservation: Introduction On the left side of your IntNB, address the following: • What would happen if all of the jackrabbits in a food web died suddenly? • Is the disappearance of one species from Earth important, or will another species fill its niche?

22. Biodiversity and Conservation: What is biodiversity? Biodiversity • What is Biodiversity? The variety of life in an area that is determined by the number of different species in that area. • There are 2 main types: Genetic Diversity Species Diversity

23. Biodiversity and Conservation: Why is biodiversity important? Biodiversity Penicillin: Derived from bread mold Teosinte: A distant relative of corn Domestic corn plant Madagascar Periwinkle: Used to treat childhood forms of leukemia

24. Biodiversity and Conservation: Extinctions Extinction Rates • The gradual process of becoming extinct is known as background extinction. • Mass extinctions: When a large percentage of all living species become extinct in a relatively short period of time. • 250 MYA: Over90% of species died

25. Biodiversity and Conservation: Extinctions Estimated number of Extinctions since 1600

26. Biodiversity and Conservation: Extinctions Five Most Recent Mass Extinctions Cretaceous Period (65 MYA) Triassic Period (200 MYA) Permian Period (250 MYA) Devonian Period (360 MYA) Ordovician Period (444 MYA)