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Cambridge University Science Magazine
Across nature there are an abundance of species that are virtually indistinguishable from one another. This can be because they are closely related, or because a certain appearance has been selected for in separate species by evolutionary pressures. In some of these cases, we can use modern genetic techniques to determine species identity, however, this is

not always feasible. In these cases, some of the old-school techniques can still be valuable. One of which being the careful examination of the genitals of individuals from each population. Genitals change very fast in evolutionary time as there is strong evolutionary pressure to prevent mating with similarly appearing species. This is because mating with a member of a different species won’t lead to the production of offspring, and is at best a waste of time and energy. What better way to ensure this can’t happen than to be physically incapable of the act? Due to this, genitals can often provide handy clues. Even in the 21st century this technique has revealed new insights, for example separating the Cryptic Wood White from the Wood White butterfly in 2001. With anthropogenic stressors driving species loss and biodiversity changes, an accurate knowledge of current species and their distributions is vital. Genital morphology is still an appreciable tool in our technical belt to accomplish this task.

By Billy Morris.