Assortative mating

Definition

Assortative mating is a non-random mating pattern where individuals with similar phenotypes or genotypes are more likely to pair up than those with dissimilar traits. This behavior can lead to an increase in genetic similarities within a population and can affect allele frequencies over time, influencing the overall genetic structure and evolution of the population.

5 Must Know Facts For Your Next Test

1. Assortative mating can lead to increased homozygosity, meaning that alleles become more similar within a population due to the preference for similar mates.
2. Positive assortative mating occurs when like individuals mate, while negative assortative mating happens when unlike individuals mate, leading to different evolutionary outcomes.
3. This type of mating can influence the distribution of traits in a population and may contribute to speciation events by reducing gene flow between groups.
4. Assortative mating is often observed in species where certain traits are desirable for reproductive success, such as in many bird species that choose mates based on plumage color.
5. Changes in assortative mating patterns can reflect environmental changes or shifts in social behaviors, potentially impacting population dynamics.

Review Questions

• How does assortative mating influence genetic diversity within a population?
  • Assortative mating influences genetic diversity by promoting the pairing of similar individuals, which can lead to increased homozygosity. This means that the genetic variation within that population may decrease as alleles become more similar. In contrast, disassortative mating tends to maintain or increase genetic diversity by mixing different traits, showcasing how these mating patterns can have significant effects on the genetic makeup of populations.
• Compare and contrast positive and negative assortative mating in terms of their effects on allele frequencies.
  • Positive assortative mating leads to individuals with similar traits breeding together, which increases the frequency of those shared traits and associated alleles within the population. This can result in a more homogeneous gene pool. Conversely, negative assortative mating encourages diversity by pairing individuals with differing traits, which may promote a wider range of allele frequencies and increase heterozygosity. Thus, while positive assortative mating can narrow genetic variation, negative assortative mating helps maintain it.
• Evaluate the potential evolutionary implications of changes in assortative mating patterns due to environmental shifts.
  • Changes in assortative mating patterns can have profound evolutionary implications, especially in response to environmental shifts. For instance, if a habitat alters and individuals begin to select mates based on new traits advantageous for survival in that environment, this could accelerate adaptive evolution. If positive assortative mating becomes more prevalent under these conditions, it could lead to reduced genetic diversity and potentially increase vulnerability to diseases or environmental changes. On the other hand, re-establishing negative assortative mating might restore genetic variability and resilience in the population.

Related terms

disassortative mating: A mating pattern where individuals with dissimilar phenotypes or genotypes are more likely to mate, promoting genetic diversity within a population.

gene flow: The transfer of alleles or genes from one population to another, which can introduce new genetic variation and affect the genetic makeup of populations.

sexual selection: A mode of natural selection where individuals with certain inherited traits are more likely to attract mates, influencing the evolution of those traits.