This is strong evidence that the clymene dolphin is a naturally occurring hybrid of the spinner and striped dolphins, said Amaral. Continued hybridization may still occur between the clymene dolphin's parent species, although at low levels, the study authors added.
The birth of a new species, known as speciation, is often thought to happen when one species splits into two or more isolated populations that diverge as they amass differences over time due to a lack of interbreeding.
Hybrids are usually infertile, with the mule—a cross between a male donkey and a female horse—being the most familiar example of this.