Phylogenetic relationships and demographic histories of the Atherinidae in the Eastern Atlantic and Mediterranean Sea re-examined by Bayesian inference.

Abstract

The aim of our study is to examine the phylogenetic relationship, divergence times and demographic history of the five close-related Mediterranean and North-eastern Atlantic species/forms of Atherina using the full Bayesian framework for species tree estimation recently implemented in ∗BEAST. The inference is made possible by multilocus data using three mitochondrial genes (12S rRNA, 16S rRNA, control region) and one nuclear gene (rhodopsin) from multiple individuals per species available in GenBank. Bayesian phylogenetic analysis of the complete gene dataset produced a tree with strong support for the monophyly of each species, as well as high support for higher level nodes. An old origin of the Atherina group was suggested (19.2 MY), with deep split events within the Atherinidae predating the Messinian Salinity Crisis. Regional genetic substructuring was observed among populations of A. boyeri, with AMOVA and MultiDimensional Scaling suggesting the existence of five groupings (Atlantic/West Mediterranean, Adriatic, Greece, Black Sea and Tunis). The level of subdivision found might be consequence of the hydrographic isolation within the Mediterranean Sea. Bayesian inference of past demographic histories showed a clear signature of demographic expansion for the European coast populations of A. presbyter, possibly linked to post-glacial colonizations, but not for the Azores/Canary Islands, which is expected in isolated populations because of the impossibility of finding new habitats. Within the Mediterranean, signatures of recent demographic expansion were only found for the Adriatic population of A. boyeri, which could be associated with the relatively recent emergence of the Adriatic Sea.