Microsatellite and mitochondrial DNA assessment of population structure and stocking effects in Arctic charr Salvelinus alpinus (Teleostei: Salmonidae) from central Alpine lakes

Abstract

Despite geographical isolation and widespread phenotypic polymorphism, previous population genetic studies of Arctic charr, Salvelinus alpinus, have detected low levels of intra‐ and interpopulation variation. In this study, two approaches were used to test the generality of low genetic diversity among 15 Arctic charr populations from three major drainages of the central Alpine region of Europe. First, a representative subsample of each drainage was screened by PCR–RFLP analysis of mtDNA using 31 restriction enzymes. All individuals but one shared an identical haplotype. In contrast, microsatellite DNA variation revealed high levels of genetic diversity within and among populations. The number of alleles per locus ranged from six to 49, resulting in an overall expected heterozygosity from 0.72 ± 0.09 to 0.87 ± 0.04 depending on the locus. Despite evidence for fish transfers among Alpine charr populations over centuries, genetic diversity was substantially structured, as revealed by hierarchical Φ statistics. Eighteen per cent of total genetic variance was apportioned to substructuring among Rhône, Rhine, and Danube river systems, whereas 19% was due to partitioning among populations within each drainage. Cluster analyses corroborated these results by drainage‐specific grouping of nonstocked populations, but also revealed damaging effects of stocking practices in others. However, these results suggest that long‐term stocking practices did not generally alter natural genetic partitioning, and stress the importance of considering genetic diversity of Arctic charr in the Alpine region for sound management. The results also refute the general view of Arctic charr being a genetically depauperate species and show the potential usefulness of microsatellite DNAs in addressing evolutionary and conservation issues in this species.

High genetic diversity in cryptic populations of the migratory sutchi catfish Pangasianodon hypophthalmus in the Mekong River

“…The discrepancy between both molecular markers can be partially explained by a weak correlation between mitochondrial and nuclear diversity, based on independent demographic processes imposed by historical events (eg Brunner et al, 1998;Bernatchez et al, 2002). A nonexclusive second explanation for these discrepancies may be related to different mutation rates.…”

SPECIES FLOCK IN THE NORTH AMERICAN GREAT LAKES: MOLECULAR ECOLOGY OF LAKE NIPIGON CISCOES (TELEOSTEI: COREGONIDAE:COREGONUS)

“…Differentiation indices are expected to be lower with hypervariable loci such as micro satellites relative to those obtained with less polymorphic markers such as enzymatic loci (Jin and Chakraborty 1995;Slatkin 1995;Rousset 1996;Estoup and Angers 1998;. However, microsatellites have suecessfully been used to detect a wide range of differentiation levels, revealing strong genetic differentiation at both local (e.g., Angers and Bernatchez 1998;) and large (e.g., Paetkau et al 1995;Brunner et al 1998) geographical scales, as well as contrasted levels of differentiation at the intraspecific level (Estoup et al 1995a;Tessier et al 1997;Goodman 1998). More importantly, significant but low levels of differentiation comparable to those in this study have also been documented in other systems analyzed with micro satellite markers (Allen et al 1995;Garcia de Le6n et al 1997;van Oppen et al 1997).…”

Divergence of Salvelinus species from northeastern Asia based on mitochondrial DNA

“…The comparative allozymes analysis and a small mtDNA section only suggest genetic isolation between the northern and southern Dolly Varden populations from this region (Salmenkova et al 2000). A discrepancy between the results of allozyme and mtDNA analyses was also observed in other Salvelinus charrs (Brunner et al 1998(Brunner et al , 2001, and may be attributed to a relatively higher rate of mtDNA sequence divergence and to a greater effect of gene drift on mtDNA genome compared to the nuclear genome. The position of S. m. krascheninnikovi in the phylogeny on the analysis of mtDNA was not surprising and was consistent with previous allozyme and karyological data (Cavender 1984;Frolov 2000;Osinov 2001), but contradicts the results from a comparative study of the nucleotide sequence in the first transcribed spacer (ITS1) of the rRNA nuclear genes (Phillips et al 1999).…”