Asexual lizards, virgin births and clones—the all‑female species of the animal kingdom (opens in new tab)

It may sound too bizarre to be true, but the Amazon molly (Poecilia formosa), a fish that inhabits rivers, lakes, and swamps in Mexico and Texas, exists over much of its range in populations that are 100% female. In 1932, the Amazon molly became the first known vertebrate to reproduce by cloning itself, producing all-female populations. A new genetic study published in Nature has given scientists insights into the longstanding mystery about how and why this happens.