What is the primary effect of outbreeding on a population?

Outbreeding primarily leads to an increase in the number of heterozygotes within a population. This occurs because outbreeding, or mating between individuals from different populations or genetically distinct individuals within the same species, introduces new alleles into the gene pool. The mixing of different genetic backgrounds allows for greater genetic variability, and as a result, more individuals in the offspring generation will carry two different alleles for certain traits, thus becoming heterozygous.

Having a higher proportion of heterozygotes often contributes to increased biological fitness, as this genetic diversity can enhance a population’s ability to adapt to environmental changes and resist diseases. Increased heterozygosity is associated with phenotypic variation, which can offer a competitive advantage in fluctuating ecological settings.

In contrast, options relating to decreased genetic diversity, promotion of inbreeding, or reduction of hybrid vigor do not represent the main consequence of outbreeding. Instead, outbreeding is generally linked with enhanced genetic diversity and fitness, making the increase in heterozygotes the most significant effect.