Is the ballan wrasse (Labrus bergylta) two species? Genetic analysis reveals within-species divergence associated with plain and spotted morphotype frequencies

Abstract

The ballan wrasse (Labrus bergylta) is a marine fish belonging to the family Labridae characterized by 2 main morphotypes that occur in sympatry: spotty and plain. Previous studies have revealed differences in their life-history traits, such as growth and maturation; however, the genetic relationship between forms is presently unknown. Using 20 recently developed microsatellite markers, we conducted a genetic analysis of 41 and 48 spotty and plain ballan wrasse collected in Galicia (northwest Spain). The 2 morphotypes displayed highly significant genetic differences to each other (F ST = 0.018, P < 0.0001). A similar degree of genetic differentiation (F ST = 0.025, P < 0.0001) was shown using the STRUCTURE clustering approach with no priors at K = 2. In this case, the frequency of spotty and plain morphotypes was significantly different ( 2 = 9.46, P = 0.002). It is concluded that there is significant genetic heterogeneity within this species, which appears to be highly associated with the spotty and plain forms, but not completely explained by them. Given the previously demonstrated biological differences between morphotypes, and the present genetic analyses, we speculate about the convenience of a taxonomic re-evaluation of this species.

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

“…Ballan wrasse display a high variety of body colouration with two major colour patterns, plain and spotted [52]. 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.…”

The Use of Recreational Fishers’ Ecological Knowledge to Assess the Conservation Status of Marine Ecosystems

“…In all cases, population trends by species obtained from different sources were normalized to the interview-derived scale (from −2 to 2). The two morphotypes of ballan wrasse Labrus bergylta (Ascanius, 1767; Almada et al, 2016;Quintela et al, 2016), pinto (spotted and reddish) and maragota (plain greenish or brown) (sensu Villegas-Ríos et al, 2013) were treated separately when possible.…”

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

“…Hanel et al [27] reported high intraspecific genetic divergence in L. bergylta and its systematic status has raised additional interest because [30] (and references therein) showed differences in life-history traits of two main morphotypes (plain and spotted body colour patterns). Genetic differences between morphotypes were reported in [31] but only with microsatellites in one restricted region. Recently, [32] found no differences between morphotypes with genetic markers widely used in fish phylogeography.…”