Trout (Salmo trutta) mitochondrial DNA polymorphism in the centre of the marble trout distribution area

Abstract

The marble trout, a lineage of the Salmo trutta complex, is endemic to the Southern Alpine region. Although it is endangered throughout its entire distribution range, population genetic data were lacking for the central area, including the upper Etsch/Adige River system (South Tyrol, Northern Italy). A total of 672 Salmo trutta specimens, comprising phenotypic marble trout and phenotypic brown trout, from 20 sampling sites throughout South Tyrol were analysed by sequencing the complete mitochondrial DNA control region. Thirteen distinct haplotypes were identified, which clustered within three major genetic lineages: the Marmoratus (MA), the Atlantic (AT) and the Danubian (DA) lineage. 41.7% of the investigated individuals carried haplotypes of the MA lineage, 47.9% of the AT lineage and 10.4% of the DA lineage. It is noticeable that AT haplotypes were present at all sampling sites and no ''pure'' marble trout population with exclusively MA haplotypes was found. This points to a considerable impact of stocking with allochthonous brown trout, given that there is no evidence for natural colonisation by individuals of the AT lineage. However, our data indicate, for at least four localities, a limited gene flow between the native marble trout and hatchery-reared strains. Future conservation and rehabilitation measures will thus have to concentrate on the identification of remnant pure marble trout individuals from such mixed populations.

Microsatellite DNA data point to extensive but incomplete admixture in a marble and brown trout hybridisation zone

“…Accordingly, all other individuals lacking any signs of a marbled pattern were assigned to the phenotypic brown trout group (abbreviations 'm' for phenotypic marble and 'b' for phenotypic brown trout group; see Table 1). The grouping of individuals based on phenotypic traits was further supported by the significant genetic differentiation based on mtDNA data (Meraner et al 2007).…”

“…A recent study by Meraner et al (2007) based on sequence analysis of the mtDNA control region showed that in the northern part of the Etsch/Adige River system, which is the second largest river in Italy and represents the centre of the marble trout distribution range, three major mtDNA lineages can be found. In addition to the native MA lineage, the AT and the DA lineages were present, while the AD and ME lineages were absent.…”

Genetic diversity and phylogenetic origin of brown trout Salmo trutta populations in eastern Balkans

“…This haplotype differed by one base substitution from the 740 bp sequence of S. platycephalus published by Sušnik et al (2004). All 27 individuals from the Aliakmon RIVER carried the most widely distributed haplotype of the marmoratus lineage (Berrebi et al 2000;Cortey et al 2004;Meraner et al 2007). …”

“…land (Meraner et al 2007), Czech Republic and Slovakia (Kohout et al 2012). All haplotypes found in the Caspian Sea basin and two inland lake basins in Iran (Vera et al 2011;Segherloo et al 2012) and the Aral Sea basin (Griffiths et al 2009) belonged also to this group.…”

“…However, concerning only the frequencies of the haplotypes within the DaDA group, an expansion was indicated by the unimodal trend of the mismatch distribution (raggedness index not significant), by the Tajima's D test (-1.436, P < 0.05) and by the Fu's Fs (-14.227, P < 0.001). Frequencies of haplotypes revealed in this as well as previous (Duftner et al 2003;Meraner et al 2007;Griffiths et al 2009;Vera et al 2011;Segherloo et al 2012) studies were included in this analysis.…”