A tale of two seas: contrasting patterns of population structure in the small-spotted catshark across Europe

Abstract

Elasmobranchs represent important components of marine ecosystems, but they can be vulnerable to overexploitation. This has driven investigations into the population genetic structure of large-bodied pelagic sharks, but relatively little is known of population structure in smaller demersal taxa, which are perhaps more representative of the biodiversity of the group. This study explores spatial population genetic structure of the small-spotted catshark (Scyliorhinus canicula), across European seas. The results show significant genetic differences among most of the Mediterranean sample collections, but no significant structure among Atlantic shelf areas. The data suggest the Mediterranean populations are likely to have persisted in a stable and structured environment during Pleistocene sea-level changes. Conversely, the Northeast Atlantic populations would have experienced major changes in habitat availability during glacial cycles, driving patterns of population reduction and expansion. The data also provide evidence of male-biased dispersal and female philopatry over large spatial scales, implying complex sex-determined differences in the behaviour of elasmobranchs. On the basis of this evidence, we suggest that patterns of connectivity are determined by trends of past habitat stability that provides opportunity for local adaptation in species exhibiting philopatric behaviour, implying that resilience of populations to fisheries and other stressors may differ across the range of species.

Peer Review #2 of "Genetic differentiation and phylogeography of Mediterranean-North Eastern Atlantic blue shark (Prionace glauca, L. 1758) using mitochondrial DNA: panmixia or complex stock structure? (v0.2)"

“…Similar findings of genetic differences were observed in other shark species, more related to a benthic environment, such the small-spotted catshark, Scyliorhinus canicula, and the velvet belly lanternshark, Etmopterus spinax (Gubili et al, 2014;Kousteni et al, 2015). The reported evidence of genetic structure in the blue shark analyzed in this study are associated with geographical differences in sex-ratio and size.…”

Gene flow, population growth and a novel substitution rate estimate in a subtidal rock specialist, the black‐faced blennyTripterygion delaisi(Perciformes,Blennioidei,Tripterygiidae) from theAdriaticSea

“…; small‐spotted catshark, Scyliorhinus canicula : Gubili et al. ). Notably, all these taxa are poor active dispersers and/or rely on passive dispersal via water currents in planktonic life stages (or are planktonic throughout their live).…”

“…; edible sea urchin, Paracentrotus lividus: Maltagliati et al 2010; red mullet, Mullus barbatus: Maggio et al 2009; Mediterranean rainbow wrasse, Coris julis: Fruciano et al 2011; marbled goby, Pomatoschistus minutus: Mejri et al 2011; small-spotted catshark, Scyliorhinus canicula:Gubili et al 2014). Notably, all these taxa are poor active dispersers and/or rely on passive dis-Demographic model comparison using a model selection approach based on Bayes factors (BFs).…”

Population structure, connectivity, and demographic history of an apex marine predator, the bull shark Carcharhinus leucas

“…Divergence times were inferred based on a molecular clock estimate and should thus be regarded as qualitative indicators, rather than precise values. The use of the divergence between Sphyrna and Carcharhinus genera, or of the Isthmus of Panama closure as the divergence date between the Atlantic and the Indian/Pacific bull shark populations, yielded mutation rates similar to those observed in other shark species using several different fossil records (Duncan et al, 2006;Gubili et al, 2014;Karl, Castro, & Garla, 2012;Schultz et al, 2008). Using two different calibration dates, we estimated the known to travel many hundreds of kilometers upstream in freshwater rivers and lakes (Heupel & Simpfendorfer, 2008;Thorson, 1976).…”