Another aspect of sexual reproduction that is barely understood is how the sexes (male and female) evolved. One theory is that separate sexes stemmed from genetic mutations in hermaphroditic genes.
Some evidence of this theory has been elucidated from a species of wild strawberry plants which appears to be transitioning from hermaphroditism to dualality of sexes. S ingle-sex plants breed not only with one another but also with hermaphroditic plants and pass on the mutation, which can result in single-sex offspring. Although sterile plants also result, plants with genes that favor the production of fertile offspring will obviously be more successful.
It is expected that the weaknesses created by inbreeding in the hermaphrodite plants result a gradual decline in the population. Consequently, fewer chromosomes with both fertility versions will be passed on and the frequency of single-sex individuals will increase and eventaully dominate the population.