Phylogeography, population structure, and species delimitation in rockhopper penguins (Eudyptes chrysocome and Eudyptes moseleyi)

Rockhopper penguins are delimited as two species, the northern rockhopper (Eudyptes moseleyi) and the southern rockhopper (E. chrysocome), with the latter comprising two subspecies, the western rockhopper (E. c. chrysocome) and the eastern rockhopper (E. c. filholi). We conducted a phylogeographic study using multilocus data from 114 individuals sampled across 12 colonies from the entire range of the northern/southern rockhopper complex to assess potential population structure, gene flow and species limits. Bayesian and likelihood methods with nuclear and mitochondrial DNA, including model testing and heuristic approaches, support E. moseleyi and E. chrysocome as distinct species lineages with a divergence time of 0.97 Ma. However, these analyses also indicated the presence of gene flow between these species. Among southern rockhopper subspecies, we found evidence of significant gene flow and heuristic approaches to species delimitation based on the genealogical diversity index failed t...