Abstract
The European whitefish Coregonus lavaretus complex represents one of the most diverse radiations within salmonids, with extreme morphological and genetic differentiation across its range. Such variation has led to the assignment of many populations to separate species. In Great Britain, the seven native populations of C. lavaretus (two in Scotland, four in England, one in Wales) were previously classified into three species, and recent taxonomic revision resurrected the previous nomenclature. Here we used a dataset of 15 microsatellites to: (1) investigate the genetic diversity of British populations, (2) assess the level of population structure and the relationships between British populations. Genetic diversity was highest in Welsh (HO = 0.50, AR = 5.29), intermediate in English (HO = 0.41–0.50, AR = 2.83–3.88), and lowest in Scottish populations (HO = 0.28–0.35, AR = 2.56–3.04). Population structure analyses indicated high genetic differentiation (global FST = 0.388) between all populations but for the two Scottish populations (FST = 0.063) and two English populations (FST = 0.038). Principal component analysis and molecular ANOVA revealed separation between Scottish, English, and Welsh populations, with the Scottish populations being the most diverged. We argue that the data presented here are not sufficient to support a separation of the British European whitefish populations into three separate species, but support the delineation of different ESUs for these populations.
Highlights
Accurate species delineation is fundamental for the practical protection and conservation of biota (Mace 2004), but the use of genetic markers sometimes disagree with traditional morphology-based taxonomy (Bickford et al 2007; Padial et al 2010; Mayr 2011)
As this effect is not pervasive in the dataset, we suggest that the heterozygote deficit reflects genetic effects associated with the population history, e.g. low diversity, rather than the occurrence of null alleles and other locus specific abnormalities
We describe microsatellite genetic diversity and population structure in the seven native populations of European whitefish Coregonus lavaretus in Britain. These populations are of high conservation concern (Winfield et al 2013), and our results provide important information for future conservation plans
Summary
Accurate species delineation is fundamental for the practical protection and conservation of biota (Mace 2004), but the use of genetic markers sometimes disagree with traditional morphology-based taxonomy (Bickford et al 2007; Padial et al 2010; Mayr 2011). Østbye et al 2005a, b; Vonlanthen et al 2009; Præbel et al 2013a; Siwertsson et al 2013; Hudson et al 2017), but for fish biologists it represents a taxonomic challenge, as morphological similarities do not necessarily reflect shared genetic history (e.g. Præbel et al 2013a). This is due to the long-standing use of certain morphological, ecological, and meristic traits that might be environmentally influenced to discriminate coregonids into different species (Etheridge et al 2012a). The number of gill rakers on the anterior gill arch is one the main characters used (Svärdson 1952, 1979; Kottelat and Freyhof 2007), which while genetically based, has been shown to be influenced by plasticity (Lindsey 1981) and under natural selection (Ozerov et al 2015; Häkli et al 2018; Jacobs et al 2019) given its important role in feeding ecology (Kahilainen et al 2011)
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