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Population Ecology. Levels of Ecological Organization.

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Presentation on theme: "Population Ecology. Levels of Ecological Organization."— Presentation transcript:

1 Population Ecology

2 Levels of Ecological Organization

3 HABITAT – Where organism lives NICHE – An organism’s role in a community and the resources that it uses Specialist – Species with a narrow niche….have very specific requirements Example: Panda Generalist – Species with a broad niche – able to use wide variety of habitats and resources

4 Population Characteristics SIZE – Number of organisms present at a given time Extinctions often preceded by DECLINE in population size

5 Population Density Number of individuals within a population per unit area

6 Population Distribution Spatial arrangement of organisms within an area

7 Populations may grow, shrink, or remain stable Births within the population (natality) Deaths within the population (mortality) Immigration – arrival of individuals from outside the population Emigration – departure of individuals from the population

8 Growth Rate of Population Express birth and death rates per 1,000 individuals for a given time period. Referred to as “Crude” birth rate or death rate Growth Rate = (Crude birth rate + immigration rate) – (Crude death rate + emigration rate) Example: (18/1000 + 5/1000) – (10/1000 + 7/1000) = 6/1000 This population of 1000 in one year will reach 1006 in next year. Growth Rate is expressed as percentage: Growth rate x 100% 6/1000 x 100% = 0.6%

9 Exponential Growth Unregulated populations increase by exponential growth (fixed percentage each year) J shaped growth curve Occurs when organisms introduced to “new” environment Examples: Mold growing on piece of bread, Bacteria colonizing recently dead animal, Scots Pine tree after retreat of glaciers

10 Logistic Growth Limiting factors restrain population growth S shaped growth curve

11 Limiting Factors Density Dependent – Limiting factors that have stronger effect on large, dense populations than small, less crowded populations Ex: Disease, Predation, Competition for resources food, water, space Density Independent - Same effect regardless of population size Ex: Natural disasters floods, fires, hurricanes, etc. and extremes in temperature Carrying Capacity – Maximum population size of a species that a given environment can support

12 Biotic Potential and Reproductive Strategies

13 Survivorship Curves

14 Conservation of Biodiversity Creating Protected Areas for endangered species – National Parks and Reserves Ecotourism


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