Population Dynamics Overview

Study Notes

Population Dynamics

Populations are groups of individuals of the same species that live in the same area and interact with each other.
Population size is influenced by birth rate, death rate, immigration, and emigration.
Population growth models describe how populations change over time.
- Exponential growth occurs when resources are unlimited and the birth rate exceeds the death rate.
- Logistic growth models take into account environmental limitations (carrying capacity).
- The carrying capacity (K) represents the maximum population size that an environment can sustain.
Density-dependent factors affect population growth as population density increases. Examples include competition for resources, predation, disease, and stress.
Density-independent factors affect population growth regardless of population size. Examples include natural disasters and harsh weather.
Factors influencing population growth include: biotic factors (predation, competition, disease), and abiotic factors (climate, temperature, rainfall).
Population fluctuations are common and can be regular or erratic, affected by environmental changes, and often related to resource availability.

Community Dynamics

Communities are groups of interacting populations of different species in a given area.
Species richness refers to the number of different species in a community.
Species diversity encompasses both species richness and the relative abundance of each species.
Interspecific interactions involve relationships between different species.
- Competition occurs when two or more species use the same limited resource.
- Predation occurs when one species (predator) hunts and kills another (prey).
- Symbiosis encompasses relationships where two or more species live in close proximity.
  - Mutualism benefits both species.
  - Commensalism benefits one species and has no effect on the other.
  - Parasitism benefits one species (parasite) at the expense of another (host).
Keystone species are species whose presence significantly influences the structure and function of a community, even if they have relatively low abundance in the community.
Community structure refers to the organization of species in a community, such as trophic levels and species interactions.
Succession is the process of gradual change in species composition in a community over time.
- Primary succession begins in areas without soil, often after volcanic eruptions, and involves the colonization of pioneer species.
- Secondary succession occurs in areas that have been disturbed but still contain soil, often after wildfires or floods. It typically proceeds more quickly than primary succession.
Disturbances, such as fire, floods, and storms, significantly influence community structure and can even trigger succession.
Some communities are more resilient to disturbances than others, depending on factors like species diversity, and the presence of keystone species.
Factors influencing community structure and function include species interactions, the availability of resources, and environmental conditions.

Population-Community Interactions

Changes in one population can influence the dynamics of interacting populations within a community.
Predation can influence prey populations and vice-versa.
Competition for resources can influence the relative abundance of different species.
Symbiotic relationships can have important effects on population dynamics and the efficiency of resource use within a given community.
Community structure can affect the populations within the community.
Changing conditions in a community can lead to the local extinction of certain species and the evolution of others.

Description

This quiz covers key concepts of population dynamics, including factors that influence population size, growth models, and the distinction between density-dependent and density-independent factors. Test your understanding of how populations interact with their environment and the implications of carrying capacity.