Microsatellite DNA analysis of rainbow trout (Oncorhynchus mykiss) from western Alberta, Canada: native status and evolutionary distinctiveness of “Athabasca” rainbow trout

Abstract

Molecular genetic assays can contribute to conservation of aquatic taxa by assessing evolutionary and taxonomic distinctiveness, levels of genetic variation within and between populations, and the degree of introgression with introduced taxa. The Athabasca River drainage of western Alberta, Canada is one of only three (and the largest) drainages flowing east of the continental divide that contain native populations of rainbow trout (Salmonidae: Oncorhynchus mykiss). The ''Athabasca'' rainbow trout has been considered a preglacial relict worthy of special conservation measures. In addition, the native range of Athabasca rainbow trout has seen many instances of introductions of non-native populations since the beginning of the 20th century. We assayed rainbow trout from the Athabasca River drainage, from hatchery populations, and from representative populations in adjacent regions (N = 49 localities) for variation at 10 microsatelite loci to assess the level of evolutionary distinctiveness of Athabasca rainbow trout, and to assess the levels of introgression with non-native hatchery fish. We found that native Athabasca rainbow trout did not form a distinctive genetic assemblage and that the greatest amount of allele frequency variation was attributable to contemporary drainage systems (29.3%) rather than by a Athabasca/non-Athabasca distinction (12.6%). We found that 78% of all fish were confidently assigned to a ''wild'' rather than a ''hatchery'' genetic grouping and that most of the inferred introgression with hatchery fish was restricted to a few localities (N = 6). Our results suggest that: (i) Athabasca River rainbow trout are likely postglacial immigrants from adjacent populations of the Fraser River, and (ii) that there is no evidence of widespread introgression of hatchery alleles into native Athabasca River drainage rainbow trout.

A genetically distinct wild redband trout (Oncorhynchus mykiss gairdneri) population in Crane Prairie Reservoir, Oregon, persists despite extensive stocking of hatchery rainbow trout (O. m. irideus)

“…In the Spokane River drainage of Washington, Small et al (2007) describe introgression of local wild populations in some areas exposed to hatchery stocking, whereas other stocked areas show minimal genetic relationship to hatchery collections. Taylor et al (2007) found low levels of introgression among divergent hatchery and wild O. mykiss in the Athabasca River that was restricted to a select few localities within the basin. Fritzner et al (2001) observed relatively little population differentiation between hatchery trout strains and naturalorigin brown trout (Salmo trutta) from three rivers in Denmark influenced by hatchery stocking, whereas one wild population that was not influenced by stocking differed significantly from hatchery strains.…”

Conservation prioritization in widespread species: the use of genetic and morphological data to assess population distinctiveness in rainbow trout (Oncorhynchus mykiss ) from British Columbia, Canada

“…(2010): Oneu14, Ssa197, Oneu8, Ssa85, Ssa456, Omy77, Ots3, Okia3, Ots100, and Ots103. Full details of DNA extraction and data collection, and basic population genetic analyses are described in Taylor et al. (2007) and Tamkee et al.…”

Population genetic structure of North American burbot (Lota lota maculosa) across the Nearctic and at its contact zone with Eurasian burbot (Lota lota lota)

“…Note that the microsatellite admixture is calculated at the population level, while mtDNA admixture refers to the frequency of Lota l. lota (EB lineage) or L. l. maculosa (NA lineage) mtDNA in individuals in the population. Rhymer et al 2001;Fedorov et al 2003), though subspecies of closely related temperate fish are often found to interbreed freely at contact zones (reviewed in Utter 2001;Lutz-Carrillo et al 2006;Taylor et al 2007). In fact, interbreeding when no geographic barrier prevails is fundamental to the definition of fish subspecies (Nelson 1999;Haig et al 2006).…”