Answer:
Genetic variation within a population can be influenced by several factors:
Factors Increasing Genetic Variation
1. **Mutation**: Random changes in DNA sequences create new alleles.
2. **Gene Flow**: The transfer of alleles between populations through migration.
3. **Sexual Reproduction**: Combining genes from two parents creates new allele combinations.
4. **Genetic Recombination**: During meiosis, homologous chromosomes exchange genetic material, creating new allele combinations.
Factors Decreasing Genetic Variation
1. **Genetic Drift**: Random fluctuations in allele frequencies, especially in small populations, can lead to a loss of alleles.
2. **Natural Selection**: If certain alleles confer a survival or reproductive advantage, they may become more common, reducing variation.
3. **Inbreeding**: Mating between closely related individuals increases the chance of homozygosity, reducing genetic diversity.
4. **Bottleneck Effect**: A dramatic reduction in population size can result in a loss of genetic diversity.
5. **Founder Effect**: When a new population is established by a small number of individuals, it may have reduced genetic variation compared to the original population.
These factors interplay to shape the genetic makeup of populations over time.
or
Genetic variation increases through mutation, gene flow, sexual reproduction, and genetic recombination, introducing new alleles and combinations. Conversely, it decreases due to genetic drift, natural selection, inbreeding, bottleneck effects, and founder effects. Genetic drift and bottlenecks, particularly in small populations, randomly reduce allele frequencies. Natural selection favors certain alleles, reducing diversity, while inbreeding leads to homozygosity. Founder effects occur when new populations are established by few individuals, limiting genetic variation. These dynamics collectively shape population genetics over time.
Explanation:
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