Reproductive isolation and genetic differentiation of ferox trout from sympatric brown trout in Loch Awe and Loch Laggan, Scotland

Abstract

Molecular marker studies reported here, involving allozymes, mitochondrial DNA and microsatellites, demonstrate that ferox brown trout Salmo trutta in Lochs Awe and Laggan, Scotland, are reproductively isolated and genetically distinct from co‐occurring brown trout. Ferox were shown to spawn primarily, and possibly solely, in a single large river in each lake system making them particularly vulnerable to environmental changes. Although a low level of introgression seems to have occurred with sympatric brown trout, possibly as a result of human‐induced habitat alterations and stocking, ferox trout in these two lakes meet the requirements for classification as a distinct biological, phylogenetic and morphological species. It is proposed that the scientific name Salmo feroxJardine, 1835, as already applied to Lough Melvin (Ireland) ferox, should be extended to Awe and Laggan ferox.