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Dispersion spatial distribution of individuals within a population

Dispersion spatial distribution of individuals within a population. Clumped resources or living space are clumped, or because of social behavior. Three types of dispersion. Uniform (Even) social interactions result in individuals getting as far away from each other as possible.

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Dispersion spatial distribution of individuals within a population

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  1. Dispersion spatial distribution of individuals within a population

  2. Clumped • resources or living space are clumped, • or because of social behavior • Three types of dispersion.

  3. Uniform (Even) • social interactions result in individuals getting as far away from each other as possible • Three types of dispersion.

  4. Random • Ex: seed dispersal by winds or birds • Three types of dispersion.

  5. 14.3 Population Density and Distribution • Understanding Populations • Population size • # of individuals it contains • Population density • How crowded a population is • # of individuals/unit of area or volume

  6. 14.4 Population Growth Patterns Measuring Populations Population Dynamics • change in size and composition over time • Birth rate, death rate, life expectancy Population Growth Rate • Depends on birth, death, emigration (movement out of a population), and immigration (movement into a population)

  7. 14.4 Population Growth Patterns Survivorship curves • show the number of surviving members over time from a measured set of births.

  8. 14.4 Population Growth Patterns Exponential Model Increases rapidly after only a few generations Assumption • Birth rates & death rates remain constant no matter how large the population becomes Populations cannot grow indefinitely because of availability of resources and accumulation of wastes

  9. 14.4 Population Growth Patterns Logistic Model • Accounts for the influence of limiting factors • Limiting factor – restrains the growth of a population • Birth rates decline and death rates rise as population grows • Carrying capacity – the # of individuals the environment can support over a long period of time • the birth rate equals the death rate and growth stops Assumption • Carrying capacity is constant and does not fluctuate with environmental changes

  10. 14.4 Population Growth Patterns • Logistic and exponential models are not accurate representations of real populations • They are tools used to study population growth and regulation

  11. 14.4 Population Growth Patterns Population Regulation – Limiting Factors Density-independent factor – weather, floods, and fires • Reduce the population by the same proportion regardless of population size Density-dependent factor – food shortages or nesting sites • Triggered by increasing population density

  12. 14.5 Ecological Succession KEY CONCEPT Ecological succession is a process of change in the species that make up a community.

  13. 14.5 Ecological Succession Succession • a sequence of biotic changes • damaged communities are regenerated • new communities arise in previously uninhabited areas

  14. 14.5 Ecological Succession • primary succession — started by pioneer species • There are two types of succession.

  15. 14.5 Ecological Succession • 2. secondary succession — started by remaining species • There are two types of succession.

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