A first report on coexistence and hybridization of Mytilus trossulus and M. edulis mussels in Greenland

Abstract

Semi-sessile Mytilus mussels are used as indicators of climate changes, but their geographic distribution is not sufficiently known in the Arctic. The aim of this study was to investigate the taxonomic status and genetic differentiation of Mytilus populations in a Northwest Greenlandic fjord at Maarmorilik, impacted by contaminations from a former mine. In this study, mussels were collected at three sites differing in exposure to environmental factors. A total of 54 polymorphic SNPs found in the Mytilus EST and DNA sequences analyzed were successfully applied to 256 individuals. The results provided the first evidence for the existence of M. trossulus in Greenland. The mussel from M. trossulus and M. edulis taxa are shown to coexist and hybridize in the fjord. The three studied sites were found to differ significantly in the distribution of taxa with a higher prevalence of M. trossulus in the inner fjord. The identified M. edulis 9 M. trossulus hybrids mostly had a hybrid index score of about 0.5, indicating a similar number of alleles characteristic for M. trossulus and M. edulis. There was a low number of backcrosses between 'pure' taxa and hybrids. This newly discovered hybrid zone between the two taxa is unique in comparison with the Canadian populations. As Mytilus mussels in Greenland hitherto have been regarded as the one taxon M. edulis, the results have importance for biogeography and future monitoring and environmental studies.

Genetic diversity and connectivity within Mytilus spp. in the subarctic and Arctic

“…The latter is in line with the findings of Wenne et al. (), who found a higher prevalence of M. trossulus in the inner Maarmorilik fjord compared with the more saline outer fjord. Mytilus galloprovincialis normally inhabits warmer waters, but in recent years the species and M .…”

“…across the Arctic has implications for ecological and ecotoxicological research in the region. Mytilus mussels are extensively used in biological monitoring programs (Wenne et al., ). However, interspecific differences in physiology and responses to environmental pollutants have been reported (Brooks, Farmen, Heier, Blanco‐Rayon, & Izagirre, ; Fly & Hilbish, ), and thus, the lack of genetic knowledge could seriously affect the conclusions of ongoing biological monitoring.…”

Phylogenetic relationships inKerkiaand introgression betweenHauffeniaandKerkia(Caenogastropoda: Hydrobiidae)

“…; Wenne et al. ) and between closely related taxa. Several hundred kilometres, as well as high level of phylogenetic distance between our populations, can therefore cast doubt on the adequacy of postulating the introgression as a cause for similarity in the COI gene.…”

“…; Wenne et al. ) although the introgressive hybridization is most often cryptic and only revealed from studies that combine nuclear and mitochondrial DNA data. It is expected to occur across hybrid zones, in sympatry or at least parapatry, and between closely related species (e.g.…”

Single nucleotide polymorphism markers with applications in aquaculture and assessment of its impact on natural populations

“…The selection response was up to 10%, indicating that further genetic gains can be achieved through a family-based breeding programme. Recently, SNPs have been used also in studies of Mytilus from other geographic regions (Kijewski et al, 2009;Vera et al, 2010;Zbawicka et al, 2012;Wennerstrom et al, 2013;Zbawicka et al, 2014;Pino-Querido et al, 2015;Wenne et al, 2016a;Jilberto et al, 2017).…”