Genomic data supporting the publication:
Anna M. Kearns, Alex Drew, Lynn P. Pedler, Maya Penck, Stephen Donnellan and Leo Joseph. Unexpected hybridization and limited population structure uncovers perplexing taxonomic issues in the Australian, Little, and Forest Ravens. in prep.
Abstract:
Hybridization is common across the tree of life, and signals of introgression can be found in the genomes of birds world-wide. However, it is not always easy to differentiate between alternative evolutionary histories from genomic data. Here we use reduced representation sequencing to test hypotheses concerning the taxonomy and evolutionary history of a recently diverged lineage of ravens endemic to Australia. We find clear support for current species boundaries separating the Australian Corvus coronoides, Little C. mellori and Forest C. tasmanicus Ravens. Unexpectedly, however, we find genomic evidence for hybridization between C. mellori and C. coronoides in south-eastern Australia. Our data reject the hypothesis based on similar flocking behaviour, morphometrics, plumage and vocalisations that suggest the western subspecies of the Australian Raven C. c. perplexus may be sister to C. mellori. Instead, we find that C. c. perplexus is nested among other populations of C. coronoides, which themselves show little population structuring across the near continent-wide range of the species. Our genomic data reject the hypothesis that C. c. perplexus and C. c. coronoides are distinct species. Whether subspecies are warranted within C. coronoides depends on resolution of the significance of two critical sampling gaps and whether isolation-by-distance or historical allopatry and secondary contact best explain population structure. Our study highlights the diversity of biogeographic signals for widespread birds in Australia, the identification challenges existing among phenotypically similar species that also hybridise and the critical evolutionary insights that can be gained from historical museum specimens.
