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Pressures of Populations

Pressures of Populations. Section 3.2. Population growth. Population growth is limited for all populations Population change = (birth + immigration) – (death + emigration). Population growth. Immigration – the movement of individuals in to a population

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Pressures of Populations

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  1. Pressures of Populations Section 3.2

  2. Population growth • Population growth is limited for all populations Population change = (birth + immigration) – (death + emigration)

  3. Population growth • Immigration – the movement of individuals in to a population - can increase a population - can stabilize a declining population

  4. Population growth • Emigration – movement of individuals out of a population - can occur when resources become scarce

  5. Population growth • Limiting Factors • prevent the continuation of population growth Abiotic – non-living Biotic - living

  6. Population growth Examples of limiting factors: Locusts Light Air Water Plants Microbes

  7. Population growth • Competition – when organisms try to obtain the same resources as other organisms

  8. Population growth • Density–dependent – a factor that affects a population when density is high - competition - disease

  9. Population growth • Density-independent – factor that have the same effect on a population whether density is high or low • Temperature • Wildfires

  10. Survival Strategies • Opportunists – species that reproduce quickly if population falls below carrying capacity Dandelion Insects Algae

  11. Survival Strategies • Opportunists • Tend to have short life spans, large amounts of offspring • Population size changes often, grows quickly • Lives across many areas, can adapt quickly

  12. Survival Strategies • Competitors – species with adaptations that allow them to live at or near their carrying capacity for long periods of time

  13. Survival Strategies • Competitors • Live longer with fewer offspring • Offspring take a longer time to develop • Animals take care of young longer • Not distributed across wide areas • Greater number of offspring live to reproduce

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