Will the genomics revolution finally solve the Salmo systematics?

Abstract

On one hand, studies on Salmo biological variations during the last centuries have led to the morphological description of several Salmo species (> 50). On the other hand, Salmo trutta is seen as a polymorphic species, i.e. including populations with different morphotypes and ecotypes, subdivided into nine genetically divergent evolutionary lineages. For 30 years, phylogeographic and phylogenetic investigations tried to solve the Salmo systematic problem using the mitochondrial control region, sometimes combined with other mitochondrial (e.g. protein-coding region or rRNA genes) or nuclear (e.g. allozymes or microsatellites) markers. With the advent of high-throughput next-generation sequencing, complete mitogenomes were made available for Salmo phylogenetic studies. Even better, complete genome or chromosomes with annotations as well as genes of interest can now be loaded from public database. However, in the genomic era, some challenges still need to be addressed such as an appropriate taxon sampling or the identification of orthologous genes before having an accurate phylogeny. In the present review, I examine how traditional molecular markers contributed to our knowledge of trout systematics, and what we can expect from the genomics revolution.