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Populations Interdependence in Nature

Populations Interdependence in Nature. Chapter 5. Describing Populations. Group of organisms of a single species that lives in a given area Studied by Geographic range Density and distribution Growth rate Age structure. Describing Populations. Geographic range

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Populations Interdependence in Nature

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  1. PopulationsInterdependence in Nature Chapter 5

  2. Describing Populations • Group of organisms of a single species that lives in a given area • Studied by • Geographic range • Density and distribution • Growth rate • Age structure

  3. Describing Populations • Geographic range • The area inhabited by a population (where they live) • Native (natural) range vs. introduced range • Hydrilla • Zebra mussels • Density and distribution • Number of individuals per unit area • Three general types • Random • Uniform • clumped

  4. Growth Rate Determines whether the size of a population increases, decreases or stays the same Age structure The number of males and females of each age a population contains Describing Populations

  5. Population Growth • Birthrate vs. death rate • Higher birthrate – population grows • Higher death rate – population shrinks • Equal rates – zero growth • Immigration vs. emigration • Imm- growth caused by moving in from elsewhere • Em- decline caused by leaving a population range

  6. Exponential Growth The larger a population, the faster it grows Under ideal conditions with unlimited resources, populations will grown exponentially Causes a J-shaped curve when graphed Logistic Growth Phases of growth Exponential Growth slows Growth stops Causes an S-shaped when graphed Carrying capacity – the maximum number of individuals of a particular species a particular environment can support Types of Growth

  7. Limits to Growth • Limiting factors – controls the growth of a population • Determine the carrying capacity of an environment

  8. Density-dependent Competition Predation Herbivory Parasitism Disease Stress from overcrowding Density-independent Unusual weather Natural disaster Two types of limiting factors

  9. Human Population Growth • Tends to increase • Rate of increase has changed over time • Causes of increase – advance of civilization

  10. Patterns of Human Population Growth • Demography – study of human populations • Looks at the characteristics of human population • Tries to explain how populations will change over time

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