Phylogeographic structure of a protogynous hermaphrodite species, the ballan wrasse Labrus bergylta, in Ireland, Scotland, and Norway, using mitochondrial DNA sequence data

Abstract

D'Arcy, J., Mirimin, L., and FitzGerald, R. Phylogeographic structure of a protogynous hermaphrodite species, the ballan wrasse Labrus bergylta, in Ireland, Scotland, and Norway, using mitochondrial DNA sequence data. – ICES Journal of Marine Science, 70: 685–693. The ballan wrasse, Labrus bergylta, is a protogynous hermaphrodite marine fish species that inhabits coastal waters of the eastern North Atlantic. Sequential hermaphrodite species tend to be characterized by a skewed sex ratio, which is thought to lead to marked population structuring due to a reduced effective number of breeders. Furthermore, due to its large body size (compared with other wrasse species) and its peculiar feeding behaviour, this species has been identified as a candidate cleaner fish to be used in parasite control of farmed finfish. In the present study, we used mitochondrial DNA (control region) sequence data to investigate the genetic diversity and population structuring of ballan wrasse in waters around the British Isles and southern Norway. Ballan wrasse in southern Norway showed lower levels of genetic diversity than around the British Isles, which appear to be the result of historical demographic events (population bottleneck followed by expansion). Analysis of mismatch distributions and the presence of two highly divergent clades unevenly represented in Atlantic and Scandinavian regions suggest distinct recolonization patterns in these two regions. These results provide a first insight on the status of wild populations of ballan wrasse in the eastern North Atlantic, with implications for conservation and management.

Historical gene flow constraints in a northeastern Atlantic fish: phylogeography of the ballan wrasseLabrus bergyltaacross its distribution range

“…Finally, the demographic and spatial expansion of most of the species' populations. Taken together, these findings agree with and expand those found in [33] for the North Sea.…”

“…This study extends the previous study in [33] and our potential knowledge of the species phylogeography and genetic structure by: (i) covering the species geographical distribution and (ii) analysing a nuclear fragment (the first intron of the S7 ribosomal protein gene) in addition to the mitochondrial CR fragment. The present genetic assessment will aid conservation and management of the species by providing essential information: (i) on potential effects associated with individual translocations or the exploitation of wild cleaner fish in salmonid fish farms in the North Sea and (ii) for stock assessment studies of local fisheries in the central northeastern Atlantic.…”

“…KU751889-KU752182). Additional sequences available in GenBank were obtained from [32,33] (electronic supplementary material, table S1 provides the original reference for each individual sequence).…”

“…A phylogeographic study of the ballan wrasse based on the control region (CR) of mitochondrial DNA has recently been published in [33]. Focusing in the northern distribution range of the species, around the British Isles and southern Norway, this study showed reduced levels of mitochondrial genetic diversity towards northern latitudes, and the presence of two divergent clades showing evidence of population expansion.…”

Gender distribution, sexual size dimorphism and morphometric sexing in ballan wrasse Labrus bergylta

“…bergylta . This is particularly true when comparing populations from Atlantic and Scandinavian regions that constitute, in terms of mitochondrial DNA sequence structure, two divergent clades with low population structuring within each region (D'Arcy et al , ).…”