Homozygosity

Definition

Homozygosity refers to the genetic condition where an individual has two identical alleles for a specific gene. This condition can arise from inbreeding or genetic bottlenecks, leading to reduced genetic diversity. When populations experience a decrease in size, they may become more homozygous, which can impact their overall health and adaptability.

5 Must Know Facts For Your Next Test

1. In small populations, increased homozygosity can lead to inbreeding depression, resulting in lower fitness and survival rates due to harmful recessive alleles becoming more expressed.
2. Genetic bottlenecks drastically reduce the genetic variation within a population, leading to a higher chance of homozygosity and associated negative effects on population health.
3. Homozygosity can diminish the ability of a population to adapt to changing environmental conditions, as there are fewer alleles available for natural selection to act upon.
4. Genetic rescue involves introducing new individuals into a homozygous population to increase heterozygosity and improve genetic diversity, enhancing survival chances.
5. Certain species that have undergone severe population declines show elevated levels of homozygosity, which can compromise their reproductive success and resilience to disease.

Review Questions

• How does homozygosity relate to the concepts of inbreeding and genetic bottlenecks?
  • Homozygosity is closely linked to both inbreeding and genetic bottlenecks. When populations are small due to factors like habitat loss or natural disasters, they often experience genetic bottlenecks that limit their genetic diversity. This results in increased homozygosity as the remaining individuals tend to breed among themselves, leading to inbreeding. The consequences of these processes can be detrimental, as higher levels of homozygosity can lead to the expression of harmful recessive traits and decreased overall fitness.
• Discuss the implications of homozygosity for conservation strategies aimed at small or endangered populations.
  • Homozygosity presents significant challenges for conservation efforts targeting small or endangered populations. It can result in inbreeding depression, which diminishes individual fitness and reproductive success. To counteract these effects, conservationists may implement strategies such as genetic rescue, where individuals from genetically diverse populations are introduced to increase heterozygosity. This helps restore genetic variation and improve the adaptive capacity of the population, ultimately enhancing its chances of survival in changing environments.
• Evaluate the role of homozygosity in shaping the evolutionary trajectory of endangered species facing habitat fragmentation.
  • Homozygosity plays a critical role in shaping the evolutionary trajectory of endangered species impacted by habitat fragmentation. As habitats become divided and populations isolated, gene flow between groups is reduced, leading to increased homozygosity due to limited mating options. This can hinder the evolutionary potential of these species by restricting their ability to adapt to environmental changes or resist diseases. Consequently, addressing issues related to homozygosity through habitat restoration and creating wildlife corridors is essential for ensuring long-term survival and adaptability of these species.

Related terms

Heterozygosity: The genetic condition where an individual has two different alleles for a specific gene, often associated with increased genetic diversity and adaptability.

Genetic Drift: A mechanism of evolution that refers to random changes in allele frequencies within a population, which can lead to increased homozygosity in small populations.

Inbreeding Coefficient: A measure of the likelihood that two alleles at a locus are identical by descent, reflecting the degree of inbreeding within a population.