Observed patterns strengthen subspecies designation
In summary, the genetic patterns we revealed strengthen the subspecies designation of A. marina . The generally higher level of average genetic divergence among subspecies than structured populations, the distinct levels of genetic diversity within each subspecies, and the clear delineation of subspecies in a small portion of the genome complement the diagnostic morphological differences and indicate substantial divergence among subspecies analogous to full species. The obvious admixture when in contact and low differentiation across the majority of the genome indicate that the subspecies have not yet formed full species. The recognizable trifurcate split of the designated subspecies is coupled with gene flow events, leading to reticulate evolution within A. marina . In short, the subspecies show species-like patterns in some respects and population-like patterns in others. These patterns support the idea that these taxa are intermediate between geographical populations and full species. Hence, the subspecies designation is reasonable and informative.