Final answer:
Gametic disequilibrium in sexual selection refers to the non-random association of alleles at different loci in gametes. It affects assortative mating and can lead to reproductive isolation and speciation. The phenomenon plays a role in sexual selection by influencing which allele combinations are preferentially passed on to offspring.
Step-by-step explanation:
In the context of sexual selection, gametic disequilibrium refers to the non-random association of alleles at different loci in a given population's gametes. This non-randomness can be influential in sexual selection where certain traits are preferred, leading to assortative mating.
Considering reproductive isolation, prezygotic barriers like temporal isolation and gametic barriers, as well as postzygotic barriers, are mechanisms that prevent different species from interbreeding. Gametic disequilibrium may arise when certain allele combinations confer higher fitness in certain environments. This can result in a form of assortative mating where individuals with certain traits preferentially mate with others exhibiting similar traits, reinforcing specific allele combinations.
During this selective process, certain genes can 'hitchhike' along with those under selection, leading to a non-random distribution of alleles. This biased gene assortment and fertilization is an antithesis to the random fertilization principle and can accelerate speciation, especially in sympatric speciation where differentiating populations share the same geographic area.