When Two Species Merge into One – #365papers – 2018 – 60

Kearns, Restani, Szabo, Schoder-Nielsen, Kim, Richardson, Marzluff, Fleisher, Johnsen, and Omland, 2018, Genomic evidence of speciation reversals in ravens: Nature Communications, v. 9, 906

What’s it about?

The authors describe how what were once two distinct lineages of ravens (the Californian and the holarctic) have merged into what we now refer to as the common raven in the western United States. Using evidence from mitochondrial DNA, the authors show that not only is the common raven the result of the fusion of two lineages, but that the Chihuahuan raven, that lives alongside the common raven, is a descendant of the Californian raven.

Why does it matter?

We kind of get it in our heads that once species have divided, they can never join again. Sure, maybe they can hybridize, but that’s not a species, right? This paper show that, in fact, such hybrids can become new species through lineage fusion or speciation reversal.

Why did I read this?

The notion of two species merging into one was interesting to me. I’ve seen discussion of this related to human evolution. This paper has helped me understand this better.

What did I learn?

Species reversals can happen, and the mechanism doesn’t seem too complex.