La evolución de las salamandras unisexuales (no tienen machos) ha sido rastreada hasta millones de años atrás.https://buff.ly/2Ab80cV
Unisexual salamander evolution: A long, strange trip: Study finds surprisingly long stretches of celibacy -- ScienceDaily: The reproductive history of the unisexual, ladies-only salamander species is full of evolutionary surprises. In a new study, biologists have traced the animals' genetic history back 3.4 million years and found some head-scratching details -- primarily that they seem to have gone for millions of years without any DNA contributions from male salamanders and still have managed to persist.