Negative assortative mating

Negative assortative mating is a mating pattern in which individuals with dissimilar phenotypes or genotypes tend to mate with each other more frequently than would be expected under a random mating pattern. This concept is an important aspect of evolutionary biology and population genetics, as it can influence the genetic diversity and evolutionary trajectory of a population. Negative assortative mating contrasts with positive assortative mating, where individuals with similar phenotypes or genotypes are more likely to mate.

Overview

In the context of sexual selection, negative assortative mating can be driven by various factors, including the desire to increase genetic diversity within offspring, which can lead to increased fitness and survival advantages. This type of mating pattern is observed in many species, including humans, and can have significant implications for the study of genetic diversity, speciation, and disease resistance.

Mechanisms

Several mechanisms can lead to negative assortative mating. These include behavioral preferences, where individuals actively select mates based on differing traits, and spatial or temporal separation, where mating preferences are influenced by environmental factors that lead to encounters with dissimilar individuals. Additionally, genetic mechanisms, such as major histocompatibility complex (MHC) based mate choice, can drive negative assortative mating by favoring mates with dissimilar immune system genes.

Consequences

The consequences of negative assortative mating are diverse. It can increase genetic diversity within a population, which is beneficial for the adaptability and resilience of the species. Increased genetic diversity can lead to a broader range of traits and abilities within the population, potentially enhancing survival in changing environments. However, negative assortative mating can also complicate genetic studies and conservation efforts, as it influences the genetic structure of populations in ways that may not be immediately apparent.

In Humans

In humans, negative assortative mating has been observed in certain traits, such as immunogenetics where individuals are more likely to choose partners with dissimilar immune system genes. This preference can enhance the immune capabilities of offspring, providing a selective advantage. However, negative assortative mating in humans can also occur for non-genetic reasons, including cultural, social, and economic factors.

See Also

• Assortative mating
• Sexual selection
• Genetic diversity
• Speciation