Allozyme variation in populations of Atlantic salmon located throughout Europe: diversity that could be compromised by introductions of reared fish

Use of multiple markers demonstrates a cryptic western refugium and postglacial colonisation routes of Atlantic salmon (Salmo salar L.) in northwest Europe

“…However, the sampling range of this study was restricted compared with those of Bourke et al (1997) and King et al (2001). Within northwest Europe, genetic diversity was found to be highest in UKSouthwest (A r ¼ 12.276, H e ¼ 0.86) and lowest in UKSouth (A r ¼ 7.396, H e ¼ 0.767), although this latter estimate was still higher than previously reported for other regions (King et al, 2001;Säisä et al, 2005;Tonteri et al, 2005).…”

“…This is particularly marked for France and England-a maximum of five samples from across the region were included in studies by Bourke et al (1997) and Verspoor et al (1999). In the only studies to focus directly on this region, Payne et al (1971) and Child et al (1976) described two lineages based on polymorphisms at the transferrin locus.…”

“…Much has been achieved in other areas of Europe since these early studies. For example, although no evidence for a Boreal-Celtic divide has since been observed (Ståhl, 1987;Bourke et al, 1997;Verspoor et al, 1999;Consuegra et al, 2002), due to the high genetic diversity consistently reported for Britain and Ireland (Verspoor et al, 1999;Nilsson et al, 2001;Consuegra et al, 2002), this region has been proposed as a contact zone for salmon expanding out of multiple refugia. Sound evidence of a refuge for Atlantic salmon in this region comes in the form of bone relics recovered from a cave in the Iberian Peninsula, which demonstrates the presence of Atlantic salmon in this area for at least the past 40 000 years, that is, during the last glacial period (Consuegra et al, 2002).…”

“…In addition, a glacial lake present in the southern North Sea has been proposed as a potential refuge for Atlantic salmon colonising west into the Atlantic and North Sea drainages, east into the Baltic (Verspoor et al, 1999;Säisä et al, 2005) and north into the White and Barents Seas (Verspoor et al, 1999;Asplund et al, 2004;Tonteri et al, 2005), in line with Payne et al's (1971) 'Boreal' hypothesis. However, the allozyme studies of Verspoor (1986), Ståhl (1987) and Bourke et al (1997) have been brought into question by the revelation that a commonly used isoenzyme (ME-2, mMEP-2*) is likely to be acting under selection pressures (Verspoor and Jordan, 1989;Bourke et al, 1997) and as such is not a suitable marker for phylogeographic studies. This may also be the case for transferrin (Verspoor and Jordan, 1989) as used by Payne et al (1971) and Child et al (1976) in the initial investigations.…”

Transgenic Salmon: Science, Politics, and Flawed Policy

“…The former include, but are not limited to, size-selective harvesting, stock-enhancement efforts, transplantation across drainages and ecosystems, and increasing importance of commercial and recreational objectives; the latter derive (in part) from hydro-electric dams, acid rain, agricultural (and other) run-off, increased sedimentation and water temperature due to deforestation, and stocking of native (striped bass) and non-native (rainbow & brown trout) salmonid predators. Despite these challenges, evidence of genetically-differentiated population structuring is still evident for salmon at local, regional, and continental scale based on allozyme, mitochondrial, and nuclear DNA analyses (Ståhl, 1987;Bourke et al, 1997;Bermingham et al, 1991;McConnell et al, 1995;Taggart et al, 1995;King et al, 2001). The temporal stability of this structure has been traced over decades through the analysis of genetic material contained in archived scales (Nielsen et al, 1997;Tessier & Bernatchez, 1999).…”