title: Molecular markers reveal spatially segregated cryptic species in a critically endangered fish, the common skate (Dipturus batis).
abstract: Many sharks and skates are particularly vulnerable to overfishing because of their large size, slow growth, late maturity and low fecundity. In Europe dramatic population declines have taken place in common skate (Dipturus batis L.), one of the largest demersal fish in regional shelf seas, leading to extirpations from substantial parts of its former range. Here we report the discovery of cryptic species in common skate collected from the northeast Atlantic continental shelf. Data from nuclear microsatellite markers indicated two clearly distinct clades and phylogenetic analysis of mitochondrial DNA sequences demonstrated monophyly of each one of them. Capture locations showed evidence of strong spatial segregation, with one taxon occurring mainly in waters off the southern British Isles and around Rockall, while the other was restricted to more northerly shelf waters. These apparently cryptic species showed overlapping substrate and depth preferences, but distributional limits were closely related to temperature gradients, potentially indicating thermal limits to their distributions. This discovery of hidden diversity within a large, critically endangered marine vertebrate demonstrates how marine biodiversity can be underestimated, even in such a relatively well-studied and heavily exploited region.
authors.affiliation: Marine Biological Association of the UK, The Laboratory, Citadel Hill, Plymouth, UK. andiff@mba.ac.uk
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Griffiths
authors.forename: David W
authors.initials: DW
authors.lastname: Sims
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Cotterell
authors.forename: Aliya
authors.initials: A
authors.lastname: El Nagar
authors.forename: Jim R
authors.initials: JR
authors.lastname: Ellis
authors.forename: Arve
authors.initials: A
authors.lastname: Lynghammar
authors.forename: Matthew
authors.initials: M
authors.lastname: McHugh
authors.forename: Francis C
authors.initials: FC
authors.lastname: Neat
authors.forename: Nicolas G
authors.initials: NG
authors.lastname: Pade
authors.forename: Nuno
authors.initials: N
authors.lastname: Queiroz
authors.forename: Bárbara
authors.initials: B
authors.lastname: Serra-Pereira
authors.forename: Toby
authors.initials: T
authors.lastname: Rapp
authors.forename: Victoria J
authors.initials: VJ
authors.lastname: Wearmouth
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Genner
mesh_terms: D000818:Animals; D044822:Biodiversity; D002467:Cell Nucleus / Q000235:genetics; D004272:DNA, Mitochondrial / Q000235:genetics; D056727:Endangered Species; D005060:Europe; D005828:Genetics, Population; D018895:Microsatellite Repeats / Q000235:genetics*; D009792:Oceans and Seas; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D012860:Skates, Fish / Q000145:classification / Q000235:genetics; D013045:Species Specificity
chemical_list: D004272:DNA, Mitochondrial