Question

Several ideas might explain the persistence of alleles that lower individual fitness. Label the lettered parts of your answer. A. What is a kin-selected gene? B. What is a sexually antagonistic gene? C. Which of these two best explains the persistence of alleles associated with male homosexuality in human populations? Explain your thinking.

Answer 1

A) A kin selected gene is one that codes for a characteristic whose evolution is driven by kin selection. This evolutionary strategy favours the reproductive success of an organism's relatives, even at a cost to the organism's own survival and reproduction. Kin-selection combines the number of offspring produced with the number an individual can ensure the production of by supporting others, such as siblings.

B) A sexually antagonistic gene is one that codes for a protein that is related to a behavioural, morphological, or physiological traits that benefit one sex but negativly affect the other.  Many of these differences are thought to have evolved because the sexes often have needs and strategies that do not coincide. As a consequence of the different strategies they adopt to maximize their fitness. At the genetic level, these differences trigger an evolutionary conflict between the sexes. For any given genetic locus, an allele may be favoured by selection in males, while a different allele is favoured in females. Hence, intralocus sexual conflict occurs when selection acts differentially on the same locus in the two sexes (antagonism) .

C) I think sexually antagonistic genes explains the best human homesexuality because in the case of Kin- selection it appears that homosexuals do not have an inclination to contribute to the reproductive success of their relatives compared to others enough to outweigh the costs to their own fitness. In the other hand antagonistic genes could explain the wide variety of homosexual traits in men and even women. Also it is logical that there are different alleles for the homosexual gene and that there are many individuals who are heterozygous for this gene and take advantage of certain homosexual characteristics.