The Australian blacktip shark lives in tropical waters. The common blacktip shark prefers its water subtropical and temperate. Because of the difference in habitat, these two animals have become separate subspecies with distinct physical differences.
However, there are some places where their habitats overlap. And here, along the eastern coast of Australia, there is interspecies nookie. And hybrid baby sharks.
Now, none of that is particularly shocking. Hybrid zones, where the habitats of two genetically compatible species overlap, aren't ridiculously common, but scientists have documented quite a few. What makes this finding interesting is that the two species and their hybrid have been genetically documented. Hybrid zones can be fuzzy places. What happens there calls into question how sure we can be that that what we call species really are all that different from one another.
What makes this study interesting is that researchers actually performed genetic testing on sharks caught in the hybrid zone. They found distinct genetic differences between the blacktip and Australian blacktip sharks, especially in their mitochondrial DNA. And the hybrids were identified based on genetics as well. That's something that's a lot more rare in the study of wild hybrids. The information gathered here could end up having a lot to teach us about how evolution happens and what speciation really means.