Molecular and Phenotypic Evidence of a New Species of Genus Esox (Esocidae, Esociformes, Actinopterygii): The Southern Pike, Esox flaviae

Abstract

We address the taxonomic position of the southern European individuals of pike, performing a series of tests and comparisons from morphology, DNA taxonomy and population genetics parameters, in order to support the hypothesis that two species of pike, and not only one, exist in Europe. A strong relationship emerged between a northern genotype supported by COI, Cytb, AFLP and specific fragments, and a phenotype with round spot skin colour pattern and a large number of scales in the lateral line, clearly separated from a southern genotype with other skin colour pattern and a low number of scales in the lateral line. DNA taxonomy, based on a coalescent approach (GMYC) from phylogenetic reconstructions on COI and Cytb together with AFLP admixture analysis, supported the existence of two independently evolving entities. Such differences are not simply due to geographic distances, as northern European samples are more similar to Canadian and Chinese samples than the southern Europe ones. Thus, given that the differences between the two groups of European pike are significant at the phenotypic, genotypic and geographical levels, we propose the identification of two pike species: the already known northern pike (Esox lucius) and the southern pike (E. flaviae n.sp.). The correct identification of these two lineages as independent species should give rise to a ban on the introduction of northern pikes in southern Europe for recreational fishing, due to potential problems of hybridisation.

Circumpolar phylogeography of the northern pike (Esox lucius) and its relationship to the Amur pike (E. reichertii)

“…In two publications these species have been described as E. cisalpinus [5] and E. flaviae [4]. These species are with high probability the same, with a suggested vernacular name of southern pike [4]. The type locality of E. flaviae is Trasimeno [4], the same location where we have samples of northern pike belonging to the D-loop g clade [25].…”

“…In two publications these species have been described as E. cisalpinus [5] and E. flaviae [4]. These species are with high probability the same, with a suggested vernacular name of southern pike [4].…”

“…The northern pike (E. lucius) is the only species within the genus with a circumpolar distribution, whereas E. americanus, E. masquinongy and E. niger are only found in North America and two species only in Eurasia (E. reichertii, and E. cisalpinus (synonymous with E. flaviae)) [4][5][6]. The geographic origin of the genus Esox is unclear.…”

Spatially explicit genetic structure in the freshwater sponge Ephydatia fluviatilis (Linnaeus, 1759) within the framework of the monopolisation hypothesis

“…the analysed loci, coi, itS2 and 28S are usually highly variable in other animals, and commonly used to study variability within and among populations and phylogeographic patterns (e.g. Stat et al, 2011;Lucentini et al, 2011aLucentini et al, , 2011b. on the other hand, mitochondrial dna sequences appear to be conserved in sponges and anthozoa, so that they do not provide adequate information to resolve intraspecific relationships (Shearer et al, 2002;Wörheide et al, 2002).…”

Adding nuclear rhodopsin data where mitochondrial COI indicates discrepancies – can this marker help to explain conflicts in cyprinids?

“…A high level of intraspecific mtCOI divergence is a likely indicator for cryptic diversity, i.e. putative new, or unrecognized species, pronounced phylogeographic structure, but might also result from introgressive hybridization [10][11][12][13][14][15].…”