Gene Pool Flashcards

Study Notes

Gene Pool

A gene pool is the complete set of alleles in a population of a species.

Allele Frequencies

Represents the relative frequency of an allele in a population, calculated by the ratio of each allele type to the total alleles present.
Each individual carries two alleles for any given trait, so the total number of alleles equals twice the number of individuals.

Population Genetics

Focuses on allele frequencies within populations and how these frequencies change due to various factors.

Population

Defined as all members of a particular species living in a specific region at a specific time.

Genetic Diversity

Refers to the total genetic characteristics within a species' genetic makeup.
High genetic diversity is crucial for population health and adaptability to environmental changes, increasing chances of survival during crises like droughts or disease outbreaks.

Variation

Refers to the natural differences among individuals within a species or between populations.

Factors Affecting Genetic Diversity

Key factors include:
- Mutation: Introduces new alleles.
- Environmental Selection Pressures: Influences survival and reproduction.
- Gene Flow: Exchange of alleles between populations.
- Genetic Drift: Random changes in allele frequencies, particularly in small populations, including population bottlenecks and the founder effect.

Sources of Variation

Mutation is the primary source of genetic variation, while sexual reproduction and migration also contribute to population variation.

Environmental Selection Pressures

These pressures remove less suited individuals from populations, affecting competition for resources such as food, space, and mates.

Impact of Selection Pressures

Selection pressures can favor certain phenotypes that enhance survival and reproduction, leading to shifts in allele frequencies over time.

Impact of Selection Pressures - Example 1: Rainforest

In dense rainforests, plants that can gather more light, like those with larger leaves, tend to survive and reproduce better due to light availability as a selection pressure.

Impact of Selection Pressures - Example 2: Malaria and Sickle Cell Anaemia

Sickle cell anaemia results from a recessive mutation affecting hemoglobin; while homozygous individuals are adversely affected, heterozygous individuals (carrying one normal and one sickle cell allele) are resistant to malaria, creating a selection advantage in malaria-prone regions.

Gene Flow

The transfer of alleles between populations through migration, influencing allele frequencies.
Both immigration and emigration can significantly impact allele frequencies if the migrant population is not representative of the original.

Barriers to Gene Flow

Physical barriers like mountains, oceans, or deserts can prevent populations from interbreeding, leading to geographical isolation.

Genetic Drift

Represents random changes in allele frequencies, greatly impacting small populations where chance events can have significant effects.

Founder Effect

Occurs when a new population is established by a small number of individuals from a larger population, potentially leading to a loss of genetic variation and the prevalence of rare alleles.

Bottleneck Effect

Describes a significant reduction in genetic diversity due to a sharp decline in population size, often due to catastrophic events.

Description

Explore the essential concepts of gene pools and allele frequencies through these flashcards. Each card provides a clear definition and understanding of crucial genetic terms that are fundamental in population genetics. Perfect for students looking to solidify their knowledge.