4.2: Population Ecology
- Page ID
- 108084
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- Describe how ecologists measure population size and density
- Summarize the types of population distribution
- Identify how the carrying capacity of habitats may change
- Describe how natural selection and environmental adaptation led to the evolution of particular life history patterns
- Explain the characteristics of and differences between exponential and logistic growth patterns
- Identify how population growth is regulated
- Predict the ecological consequences of unregulated growth
- Analyze the factors leading to exponential human population growth and its impacts
This 12-minute video summarizes much of the content of Unit 4.2
Question after watching: As you watch this video, consider how the West Nile Virus outbreak in Dallas, Texas illustrates the usefulness of population ecology. How would you explain what population ecology is and why it is useful to a sibling or friend?
- 4.2.1: The Scope of Ecology
- Ecology is the study of the interactions of living organisms with their environment. One core goal of ecology is to understand the distribution and abundance of living things in the physical environment. Attainment of this goal requires the integration of scientific disciplines inside and outside of biology, such as biochemistry, physiology, evolution, biodiversity, molecular biology, geology, and climatology.
- 4.2.2: What is Population Ecology?
- Ecology is often defined as the study of the distribution and abundance of organisms. Population ecologists study what determines the occurrence and abundance of species in space and time: their geographic ranges, population sizes and densities, what factors result in them being so rare or common, and why these characteristics change over time.
- 4.2.3: Life Histories and Natural Selection
- A species’ life history describes the series of events over its lifetime, such as how resources are allocated for growth, maintenance, and reproduction. Life history traits affect the life table of an organism. A species’ life history is genetically determined and shaped by the environment and natural selection.
- 4.2.4: Population Demography
- Populations are dynamic entities. Populations consist of all individuals of a species living within a specific area. Populations fluctuate based on a number of factors: seasonal and yearly changes in the environment, natural disasters such as forest fires and volcanic eruptions, and competition for resources between and within species. Demography uses a series of mathematical tools to investigate how populations respond to changes in their environment.
- 4.2.5: Population Models
- Although life histories describe the way many characteristics of a population (such as their age structure) change over time in a general way, population ecologists make use of a variety of methods to model population dynamics mathematically. These more precise models can then be used to accurately describe changes occurring in a population and better predict future changes.
- 4.2.6: Human Population Growth
- Although humans have increased the carrying capacity of their environment, the technologies used to achieve this transformation have caused unprecedented changes to Earth’s environment, altering ecosystems to the point where some may be in danger of collapse. The depletion of the ozone layer, erosion due to acid rain, and damage from global climate change are caused by human activities. The ultimate effect of these changes on our carrying capacity is unknown.