Population Ecology and Genetics

Study Notes

A group of organisms of the same species living in a specific area, capable of interbreeding.
Key characteristics include density, age structure, and population growth.

Demography focuses on population statistics like age structure, density, birth rates, deaths, and growth.
Population genetics studies the breeding structure and genetic makeup of a population.
Ontogeny distinguishes populations based on individual development – unitary organisms develop as a single unit, while modular organisms form units from a parent, like trees with clones.

Populations consist of interbreeding organisms forming a gene pool, the collective genetic information.
Gene flow, the exchange of genetic information between populations, contributes to their evolution.
Environmental pressures can influence gene frequencies, resulting in physical changes within the population.
Subpopulations ('demes') form within larger populations, with varying densities.

Density: The number of individuals per unit area, reflecting population size.
Dispersion/Distribution: The spatial arrangement of individuals within a population.
- Random Distribution: Individuals are distributed independently of each other, occurring in uniform environments with minimal interaction.
- Uniform/Regular Distribution: Individuals are evenly spaced, often due to competition.
- Clumped Distribution: The most common pattern, where individuals cluster due to resource availability or social interactions.
Temporal Dispersion: Distribution of individuals over time.
- Circadian: Daily patterns influenced by light.
- Seasonal: Changes based on temperature, humidity, and resource cycles.

Organisms move away from their original habitat for various reasons.
Dispersal types:
- Immigration: One-way movement into a new habitat.
- Emigration: One-way movement out of a habitat.
- Migration: One-way movement with a return to the original habitat.
Dispersal methods:
- Active dispersal: Movement by the organism itself, like birds or mammals.
- Passive dispersal: Movement aided by external factors like wind or water.