Global and New Caledonian patterns of population genetic variation in the deep-sea splendid alfonsino, Beryx splendens, inferred from mtDNA

Abstract

Splendid alfonsino Beryx splendens is a commercial species in several countries, but is not currently exploited in New Caledonia. Information on species biology and genetics can influence the development of fisheries and assist in their management, but the genetic structuring and diversity of B. splendens populations remain largely unknown. To improve knowledge of genetic parameters, we used mitochondrial DNA sequences to conduct a comparative study of populations from throughout the world. Fragments of 815bp of cytochrome b gene were sequenced and used to interpret the species history. We analyzed 204 individuals representing 14 geographical populations worldwide. A special focus was put on populations from New Caledonia. Analysis of variation between sequences, based on pairwise F statistics and AMOVA, demonstrated a population subdivision between the Atlantic and Indo-Pacific Oceans (Fst=0.11-0.32; P<0.05). Minimum-spanning network analysis revealed a mainly star-shaped pattern, with two lineages that may represent population expansion following a bottleneck/founder event and/or suggest colonization by migratory events over large distances. Our observations demonstrated that the species seems to follow the oceanic currents. Analysis of the nucleotide sequences revealed 122 variable sites, which defined numerous haplotypes, some associated with particular geographical regions. These data suggest an extremely high intra-specific genetic diversity, even at small scales. Focusing on the New Caledonia area, statistical analysis did not reveal sub-structuring among samples, suggesting again that at least a fraction of individuals migrate. No significant isolation by distance pattern was observed in this species (R=-0.22; P=0.79) among seamount populations in the EEZ.