Determining gender isn’t as black and white as we think. The grey area between male and female is home to numerous species of vertebrates that don’t fit the classical rules of Darwinian evolution, or any other theory. Here are just a few of the sexual misfits of the animal kingdom.
Gender equality-of sorts
Of all 15 species under the genus Cnemidophorus, the whiptail lizards, males do not exist. The lizards do not reproduce sexually, but by parthenogenesis or natural cloning, a process common in aphids and bees and rare in vertebrates. The strange thing about whiptail lizards is they must undergo sexual behaviour in order to clone-meaning they must pretend to mate anyway. Unisexual partners will mount like male and females would in order to stimulate hormonal changes that result in a “virgin birth.”
Monkeys, flamingos, and male sheep
Homosexuality isn’t so uncommon-especially since it is found in 300 species of vertebrates. After a spat, bonobos, or pygmy chimpanzees, will engage in make-up sex with partners of the same sex. Researchers suggest that this behaviour calms tensions and builds healthy social bonds. In Japanese macaques, homosexuality among females appears to be a natural eventuality as females habitually mount reluctant males in order to prompt mating. Females mounting other females, for researchers, are a side-effect behaviour with neither positive nor negative value, just as the evolution of human tailbones is no longer useful.
A clean transformation
Besides puttering around the reef clearing parasites and dead scales off other fish, the “cleaners” are an exceptional type of fish for their ability to change sexes depending on their environment. Young wrasses develop as one gender, but don’t necessarily stay that way. As adults, if the sole male of a cleaning wrasse group is removed, the largest female will begin its transformation into a male within hours and produce sperm by the tenth day. The ability to oscillate between genders is found in over 50 species of fish and invertebrates. On any given coral reef, it is estimated that 25 per cent of the fish have undergone a sex change in their lifetime.
