Life style and genetic variation in teleosts: the case of pelagic (<Emphasis Type="Italic">Aphia minuta</Emphasis>) and benthic (<Emphasis Type="Italic">Gobius niger</Emphasis>) gobies (Perciformes: Gobiidae)

The pattern of genetic variability of two species of Mediterranean gobiids was compared, with reference to their different life history traits (Aphia minuta paedomorphic and pelagic; Gobius niger metamorphosed and benthic). The aim was to evaluate how different life histories can affect the genetic structure in these marine teleosts. The study was carried out on populations of both species sampled in the western Mediterranean and in the Adriatic Sea. Seven restriction endonucleases were used for the RFLP analysis of a mitochondrial DNA segment comprising the NADH dehydrogenase subunits 3, 4L and 4. The results highlighted two different patterns of genetic variation, a weak genetic structure in A. minuta and population subdivision in G. niger. These observations may be explained not only in terms of the different dispersal capabilities of these species, but also considering that A. minuta is an abbreviate iteroparous spawner while G. niger is a protracted iteroparous spawner. Because abbreviate iteroparity is a reproductive strategy selected in stable environments with high resource availability, Pliocene and Pleistocene climate oscillations may have represented factors that negatively influenced the reproductive success of A. minuta, producing demographic fluctuations and bottlenecks, as suggested by the mismatch distribution analysis. The weak genetic structure of A. minuta populations seems to be therefore due to a more recent re-colonization of the Mediterranean basin after a severe population decline, rather than to the high vagility of this pelagic goby.