An invasive lineage of sculpins,Cottussp. (Pisces, Teleostei) in the Rhine with new habitat adaptations has originated from hybridization between old phylogeographic groups

Abstract

Fish abundance surveys in the Rhine system have shown in the past two decades that there is a rapid upriver invasion of a freshwater sculpin of the genus Cottus. These fish are found in habitats that are atypical for the known species Cottus gobio, which is confined to small cold streams within the Rhine drainage. Phylogeographic analysis based on mitochondrial haplotypes and diagnostic single nucleotide polymorphisms indicates that the invasive sculpins are hybrids between two old lineages from the River Scheldt drainage and the River Rhine drainage, although it is morphologically more similar to the Scheldt sculpins. Most importantly, however, the invasive population possesses a unique ecological potential that does not occur in either of the source populations from the Rhine or the Scheldt, which allows the colonization of new habitats that have previously been free of sculpins. Microsatellite analysis shows that the new lineage is genetically intermediate between the old lineages and that it forms a distinct genetic group across its whole expansion range. We conclude that hybridization between long separated groups has lead to the fast emergence of a new, adaptationally distinct sculpin lineage.

Concordant Genetic Estimators of Migration Reveal Anthropogenically Enhanced Source-Sink Population Structure in the River Sculpin,Cottus gobio

“…A total of 20 weirs were identified (Figure 1) and, although data on their ages were not available, landowners and Environment Agency records confirmed that weirs have been present in the River Rye catchment for at least 200 years. Since the generation time of bullheads is $1-2 years (Nolte et al 2005), this represents $100-200 bullhead generations. It is therefore reasonable to assume that weirs represent a potentially relevant influence on both long-and short-term gene flow.…”

Disruptive sexual selection on male nuptial coloration in an experimental hybrid population of cichlid fish

“…Ellstrand 1992;Rhymer & Simberloff 1996;Taylor et al 2006). Finally, hybridization may facilitate the origin of new species with new adaptations arising through a recombination of existing genes (Schliewen & Klee 2004;Nolte et al 2005) and may even facilitate bursts of adaptive radiation from hybrid swarms (Seehausen 2004). Theoretical considerations suggest that the evolutionary consequences of interspecific hybridization depend on the adaptive landscape experienced by the hybridizing populations (Buerkle et al 2003;Seehausen et al 2008).…”

A genomic view of introgression and hybrid speciation

“…Here, success depends on the fixation of favourable new gene combinations from the two species [48]. For example, there are suggestions that new hybrid gene combinations facilitated critical ecological changes in several recently proposed hybrid species, including sculpins [49], Rhagoletis flies [50], and butterflies [51,52*]. In these cases, species of hybrid origin have colonized novel habitats, most likely through the expression of transgressive traits.…”