Phylogeography of northern Dolly VardenSalvelinus malma malmabased on analysis of mitochondrial DNA

Abstract

The northern Dolly Varden, Salvelinus malma malma, is a typical representative of arctic fauna distributed in northeastern Asia and northwestern North America. Because its spawning habitats were affected by Pleistocene glacial advances over most of its natural range, S. m. malma is among the most interesting objects of phylogeographic and microevolutionary studies. We reconstructed the genealogy of mtDNA haplotypes from 27 Alaskan and Asian populations to study the influence of glacial and geological vicariance events on the contemporary population genetic structure, phylogeographic subdivision and distribution of the northern Dolly Varden. Analysis of restriction site states in three PCR-amplified mtDNA regions (ND1/ ND2, ND5/ND6, Cytb/D-loop; 47% of the mitochondrial genome) resolved 75 haplotypes in 436 fish. Similar patterns of subspecific variation apparent from hierarchical diversity and nested clade analyses of mtDNA haplotypes identify weak spatial differentiation and low levels of divergence. Our results suggest that (1) demographic history has been influenced by historical range expansions and recent isolation by distance, (2) present populations from Asia and North America were colonized from one main Beringian Refugium, and (3) that this taxon's ancestral population probably experienced a bottleneck in the Beringian Refugium during the late Pleistocene (Wisconsin) glacial period.

Life-history characteristics and landscape attributes as drivers of genetic variation, gene flow, and fine-scale population structure in northern Dolly Varden (Salvelinus malma malma) in Canada

“…This pattern is consistent with bottlenecks and founder effects in populations that postglacially colonized novel habitats as they became ice-free and, as such, harbour only a subset of the genetic variability of the source, refugial population(s) (Hewitt 1996;Provan and Bennett 2008). Assuming a Beringian origin for northern Dolly Varden (Oleinik et al 2013(Oleinik et al , 2014) and a stepping stone-like pattern of recolonization along coastal habitats as has been suggested for other fishes in the region (e.g., Wilson and Hebert 1998; but see Harris and Taylor 2010 for an alternative interior postglacial dispersal hypothesis), our results are consistent with the idea that Alaskan portions of Beringia served as the origin of contemporary populations of northern Dolly Varden and that historical factors have also been Table 1. important for driving the distribution of genetic variation in Northern Dolly Varden.…”

“…Additionally, given that freshwater-resident northern Dolly Varden occur predominately as males, then gene flow between freshwaterresident and anadromous fish from the same system should be detectable. Finally, although contemporary gene flow is likely limited (or absent) between geographically distant populations and between those isolated above impassable barriers, we hypothesized that gene flow may have historically been high between all populations given the historical postglacial colonization of this region by one Beringian lineage (Oleinik et al 2013(Oleinik et al , 2014. To assess this hypothesis, the coalescent theory-based program MIGRATE-N (version 3.6; Beerli and Felsenstein 2001;Beerli 2006Beerli , 2009) was used to infer levels of historical gene flow among populations.…”

“…Contemporary dispersal and gene flow was virtually absent between isolated and anadromous-resident forms within a given river, suggesting that these waterfalls are important barriers to contemporary gene flow even in the downstream direction and (or) other forces are operating to limit downstream (i.e., over the waterfalls) dispersal of isolated individuals, such as selection against immigrant or hybrid individuals (Nosil et al 2005). We anticipated, however, that a signal of historical gene flow might persist given that populations above and below these barriers both colonized the region from Beringia (Oleinik et al 2013(Oleinik et al , 2014. Among all comparisons, historical gene flow estimates including isolated populations were always some of the lowest recorded; however, estimates between isolated and anadromous or freshwater-resident forms from the same system were not as low.…”

Introgressive hybridization between two phylogenetic lineages of charrs ( Salvelinus : Salmonidae) in northeastern Asia

“…Our analyses of charrs throughout the northern coast of the Sea of Okhotsk revealed that all individuals from Lake Grand possessed S. malma malma mtDNA, and these results are consistent with published data (Gudkov & Radchenko, 2000;Osinov et al, 2018;Radchenko, 2003Radchenko, , 2004a. The divergence of mtDNA nucleotide sequences between the population from Lake Grand and the three populations of the Sea of Okhotsk coast was within the range of interspecific divergence for S. malma malma (Oleinik et al, 2014). On the other hand, Bayesian clustering and NJ tree based on msDNA indicated the genetic mixture of the two mtDNA lineages in the Yama River-Lake Grand basin.…”

“…The divergence of mtDNA nucleotide sequences between the population from Lake Grand and the three populations of the Sea of Okhotsk coast was within the range of interspecific divergence for S . malma malma (Oleinik et al, 2014). On the other hand, Bayesian clustering and NJ tree based on msDNA indicated the genetic mixture of the two mtDNA lineages in the Yama River–Lake Grand basin.…”