Strong population genetic structure and contrasting demographic histories for the small-spotted catshark (Scyliorhinus canicula) in the Mediterranean Sea

Abstract

Coastal and demersal chondrichthyans, such as the small-spotted catshark, are expected to exhibit genetic differentiation in areas of complex geomorphology like the Mediterranean Basin because of their limited dispersal ability. To test this hypothesis, we used a fragment of the mitochondrial cytochrome c oxidase subunit I gene and 12 nuclear microsatellite loci in order to investigate the genetic structure and historical demography of this species, and to identify potential barriers to gene flow. Samples were collected from the Balearic Islands, the Algerian Basin, the Ionian Sea, the Corinthian Gulf and various locations across the Aegean Sea. Additional sequences from the Atlantic and the Levantine Basin retrieved from GenBank were included in the mitochondrial DNA analysis. Both mitochondrial and nuclear microsatellite DNA data revealed a strong genetic subdivision, mainly between the western and eastern Mediterranean, whereas the Levantine Basin shared haplotypes with both areas. The geographic isolation of the Mediterranean basins seems to enforce the population genetic differentiation of the species, with the deep sea acting as a strong barrier to its dispersal. Contrasting historical demographic patterns were also observed in different parts of the species' distribution, most notably a population growth trend in the western Mediterranean/ Atlantic area and a slight decreasing one in the Aegean Sea. The different effects of the Pleistocene glacial periods on the habitat availability may explain the contrasting demographic patterns observed. The current findings suggest that the smallspotted catshark exhibits several genetic stocks in the Mediterranean, although further study is needed.

Improving the Conservation of Mediterranean Chondrichthyans: The ELASMOMED DNA Barcode Reference Library

“…clavata [73,106]) to accurately unravel geographical structuring of populations. Recent studies in the Mediterranean used barcode data to assess genetic differentiation of the small-spotted catshark [44,45] and their findings describe phylogeographic signals comparable to those inferred by our ELASMOMED dataset.…”

“…Fish-BOL’s efforts comprise of numerous projects covering low-level taxonomic groups and several projects that have targeted specific regional chondrichthyan faunas [37–43]. In addition, recent studies demonstrated the effectiveness of DNA barcodes in describing phylogeographic patterns in this class [22,44,45]. …”

Concordant patterns of mtDNA and nuclear phylogeographic structure reveal Pleistocene vicariant event in the green crab Carcinus aestuarii across the Siculo-Tunisian Strait

“…In addition, the unimodal distribution and L-shaped BSP trend observed for the Western African Mediterranean strongly suggest a post-glacial spatial expansion event (Crandall et al, 2012). The different effects of Pleistocene glacial cycles on habitat availability may explain the observed differences in demographic tendencies (Kousteni et al, 2014). Hence, the different patterns of demographic history among the different studied African Mediterranean regions suggest that genetic structure could also be affected by population history (Palumbi, 1994;Patarnello et al, 2007).…”

Colonization of the Mediterranean basin by the vector biting midge species Culicoides imicola: an old story

“…; Kousteni et al . ). Hewitt () suggested that during periods of glaciations, many animals and plants species have evolved into different genetic groups in the Mediterranean basin.…”