When trying to pass genes on to future generations, mating with a different species is generally the wrong way to go. Most attempts to mate between species fail. Those that succeed often result in offspring that can’t reproduce themselves. (You’ve all met the mule).
Luckily, there are all sorts of barriers that keep animals from mating with the wrong species. Eastern and western skunks share the Great Plains, but can’t mate together because they breed during different seasons. Female green tree frogs avoid mating with a closely related neighboring species by listening for differences in their call frequencies. Two millipede species may try to mate together, but attempts always fail because the necessary body parts just don’t match up. Continue reading