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Chapter 6: Populations and Community Ecology - Lesson 1: Population Distribution and Growth

Chapter 6: Populations and Community Ecology - Lesson 1: Population Distribution and Growth



  1. List the levels of complexity found in the natural world.
  2. Contrast the ways in which density-dependent and density-independent factors affect population size.
  3. Explain growth models, reproductive strategies, survivorship curves, and metapopulations.


  1. Nature exists at several levels of complexity: individuals, populations, communities, ecosystems, and the biosphere.
  2. Density-dependent factors influence an individual's probability of survival and reproduction in an manner that is related to the size of the population. Density-independent factors have the same effect on an individual's probability of survival and reproduction in populations of any size.
  3. The exponential growth model describes rapid growth under ideal conditions when resources are not limited. The logistic growth model incorporates density-dependent factors that cause population growth to slow down as populations approach their carrying capacity. Organisms have a range of reproduction patterns. At the extremes are r-selected species, which experience rapid population growth rates, and K-selected species, which experience high survivorship and slow population growth rates. Patterns of survivorship over the life span can be graphically represented as type I, II, and III survivorship curves. Metapopulations are groups of spatially distinct populations that are connected by occasional movments of individuals. These movements reduce the probability of any of the populations going extinct.
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Chapter 6 Lesson 1 Sticky Note Video

Population Ecology

In this video Paul Andersen explains how population ecology studies the density, distribution, size, sex ration, and age structure of populations. Intrinsic growth rate and exponential growth calculations are included along with a discussion of logistic growth. K-selected and r-selected species are explained along with survivorship curves.

Population Ecology: The Texas Mosquito Mystery - Crash Course Ecology #2

Population ecology is the study of groups within a species that interact mostly with each other, and it examines how they live together in one geographic area to understand why these populations are different in one time and place than they are in another. How is that in any way useful to anyone ever? Hank uses the example a of West Nile virus outbreak in Texas to show you in this episode of Crash Course: Ecology.

Chapter 6 Lesson 1 WSQ

DOK Question Stems