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

Abstract

The distribution and demographic patterns of marine organisms in the north Atlantic were largely shaped by climatic changes during the Pleistocene, when recurrent glacial maxima forced them to move south or to survive in northern peri-glacial refugia. These patterns were also influenced by biological and ecological factors intrinsic to each species, namely their dispersion ability. The ballan wrasse (Labrus bergylta), the largest labrid fish along Europe's continental margins, is a target for fisheries and aquaculture industry. The phylogeographic pattern, population structure, potential glacial refugia and recolonization routes for this species were assessed across its full distribution range, using mitochondrial and nuclear markers. The existence of a marked population structure can reflect both recolonization from three distinct glacial refugia and current and past oceanographic circulation patterns. Although isolated in present times, shared haplotypes between continental and Azores populations and historical exchange of migrants in both directions point to a common origin of L. bergylta. This situation is likely to be maintained and/or accentuated by current circulation patterns in the north Atlantic, and may lead to incipient speciation in the already distinct Azorean population. Future monitoring of this species is crucial to evaluate how this species is coping with current environmental changes.

Peer Review #1 of "Meta-analysis of northeast Atlantic marine taxa shows contrasting phylogeographic patterns following post-LGM expansions (v0.1)"

“…This pattern of pre-LGM expansion has also been reported in a number of previous studies for a variety of marine taxa (e.g. Hoarau et al, 2007;Marko et al, 2010;Ni et al, 2014;Almada et al, 2017).…”

The development of the Norwegian wrasse fishery and the use of wrasses as cleaner fish in the salmon aquaculture industry

“…These two morphotypes differs in life history traits such as growth, maturation and mortality rates [53,54] and a taxonomic reevaluation of the species has been proposed [55]. To date, knowledge of genetic population structure of ballan wrasse in Norway is limited to a couple of studies analysing mitochondrial DNA polymorphism on a few individuals from the southern coast [56,57], which makes it difficult to draw conclusions about the impact of the fishery and fish translocations on the genetic diversity.…”

Genome wide analysis reveals genetic divergence between Goldsinny wrasse populations 

“…Such population history of step-wise colonization would explain the observed phylogeny for goldsinny wrasse (see also e.g. Gysels et al 2015;Almada et al 2017). In a recent study, Mattingsdal and colleagues (2019) showed that the current-day population structure of corkwing wrasse in Scandinavia characterized by a substantial division between western and southern Scandinavia can mainly be explained with past demographic events followed by reproductive isolation and genetic drift.…”

“…Thus far, the best-studied of these species is the corkwing wrasse which displays clear population subdivisions on different geographic scales (Robalo et al 2012;Knutsen et al 2013;Blanco Gonzalez et al 2016;Mattingsdal et al 2019). Genetic studies of ballan wrasse have so far concentrated on investigation of population structure on larger geographic scales (D'Arcy et al 2013;Almada et al 2017), and on genetic divergence of different morphotypes (Quintela et al2016;Almada et al 2016). An early genetic study of goldsinny wrasse with allozyme markers showed significant differences between the southern and mid-Norway (Sundt & Jørstad 1998).…”