S7 characterization of Western European pikes Esox spp. (Actinopterygii, Esociformes)

The comparison of a 1635 bp fragment of the first intron of the S7 ribosomal protein coding gene, a commonly used phylogenetic marker, for specimens from the three European pike species Esox aquitanicus, Esox cisalpinus and Esox lucius highlights diagnostic sites and indels constituting molecular synapomorphies. Both the sequence alignment and the phylogenetic tree discriminate these three species, even with a short sequence fragment. Three Esox lucius haplogroups can be separated. These haplogroups might correspond to the evolutionary lineages highlighted by previous mitochondrial studies. Finally this study confirms hybridization between Esox aquitanicus and Esox lucius, but also the absence of geographical structure between Esox lucius haplogroups in France following restocking from East European piscicultures. The S7 marker is excellent for molecular identification, and could be used for environmental DNA.