Many many species pairs only have pre-zygote isolation[1], meaning they could have common offspring but avoid doing so, as such mixed offspring would be at dis

Many many species pairs only have pre-zygote isolation[1], meaning they could have common offspring but avoid doing so, as such mixed offspring would be at disadvantage. 1. https://en.wikipedia.org/wiki/Reproductive_isolation#Pre-copulatory_mechanisms_in_animals https://en.wikipedia.org/wiki/Reproductive_isolation#Pre-cop...