Non-random mating

Definition

Non-random mating occurs when individuals in a population do not pair or reproduce randomly, but rather have preferences for certain traits or phenotypes. This behavior leads to a selective breeding pattern that can result in increased frequencies of specific alleles and phenotypes, ultimately affecting genetic diversity and evolutionary dynamics within the population.

5 Must Know Facts For Your Next Test

1. Non-random mating can lead to significant changes in allele frequencies, impacting the genetic structure of populations.
2. Assortative mating can reinforce certain traits within a population, causing a reduction in genetic diversity over generations.
3. Inbreeding is a specific form of non-random mating that increases the likelihood of recessive genetic disorders due to the expression of deleterious alleles.
4. Non-random mating is one of the factors that can lead to deviations from Hardy-Weinberg equilibrium, alongside other factors like natural selection and genetic drift.
5. By influencing mate choice based on specific traits, non-random mating can contribute to the process of sexual selection and lead to evolutionary changes.

Review Questions

• How does non-random mating influence the genetic structure of populations?
  • Non-random mating influences genetic structure by altering allele frequencies based on mate preferences. When individuals select partners with specific traits, it increases the frequency of those traits within the population, leading to changes in genetic diversity. This selective breeding can either enhance certain desirable traits or reduce variation by favoring similar phenotypes, impacting the overall adaptability and evolution of the population.
• Discuss the relationship between non-random mating and genetic diversity within a population.
  • Non-random mating can significantly reduce genetic diversity within a population. When individuals preferentially mate with similar phenotypes (as seen in assortative mating), it leads to a concentration of specific alleles and reduces the overall gene pool. This reduction in diversity can make populations more susceptible to environmental changes and diseases since there is less variability to adapt to new challenges.
• Evaluate how non-random mating might interact with other evolutionary forces such as natural selection and genetic drift.
  • Non-random mating interacts dynamically with natural selection and genetic drift, shaping evolutionary outcomes. For example, if non-random mating favors certain advantageous traits, it can amplify natural selection by increasing the frequency of those traits in subsequent generations. Conversely, genetic drift may act on allele frequencies resulting from non-random mating, especially in small populations where random chance can have a pronounced effect. Together, these forces contribute to the complexity of evolutionary processes and population dynamics.

Related terms

Assortative Mating: A type of non-random mating where individuals with similar phenotypes or genotypes mate more frequently than would be expected under random mating.

Inbreeding:

The mating of individuals who are closely related, which can lead to increased homozygosity and a higher chance of expressing deleterious alleles.

Genetic Drift: A process that causes allele frequencies to change randomly over time due to chance events, often more pronounced in small populations.