The influence of glacial epochs and habitat dependence on the diversity and phylogeography of a coastal dolphin species: Lagenorhynchus albirostris

Abstract

In this paper we use mitochondrial and microsatellite DNA variation to investigate the mechanisms that underlie the evolution of population structure in a highly mobile marine mammal, the white-beaked dolphin. We found moderate genetic diversity (h) at mtDNA, but low nucleotide diversity (p) (0.7320 ± 0.0031 and 0.0056 ± 0.0004, respectively), consistent with expectations for a recent expansion. Analyses based on mismatch distributions further suggested a demographic expansion in the Norwegian-Barents Sea population and a spatial expansion in the British isles-North Sea population, implying distinct demographic histories. F ST values showed clear differentiation among these two populations, but no difference was found between putative populations separated by the English Channel. Our data suggest a stepwise pattern of expansion, dependent on available coastal habitat. The conservation implications are a need to protect local populations isolated by an expanse of deep water, and in particular, a population along the British coasts and in the North Sea as separate from the North Norway-Barents Sea population. It is also evident that overall diversity was reduced, probably during the last glacial epoch.

Biogeography and temporal progression during the evolution of striped dolphin population structure in European waters

“…() investigating habitat suitability for grey seals ( Halichoerus grypus ), during the LGM the higher latitudes of the North Atlantic Ocean were isolated, and only the Biscay Gulf and Iberian Peninsula were suitable for habitation. Our data suggest that population differentiation was generated in this region following the LGM, and a post‐glacial expansion associated with population structuring in the eastern North Atlantic has been discussed for other marine mammals (Banguera‐Hinestroza et al., , ; Fontaine et al., ). Of course earlier glacial/ interglacial transitions during the Pleistocene Milankovitch cycles may have had the potential to generate structure in this region as well.…”

“…Evidence for striped dolphin population expansion through the Pleistocene was provided from the Ne estimates in the ABC analyses, since the ancestor value was lower than for all extant estimates (Table ). During the Pleistocene epoch, oscillations such as changes in sea level, upwelling events, temperature alterations and changes in the distribution of food resources may have played a role in the changing dynamics of delphinid populations (see Banguera‐Hinestroza et al., ; Moura et al., ). Sea level during glacial periods within the Pleistocene is estimated to have dropped by about 110–120 m (Lambeck & Purcell, ) which may have influenced population dynamics, dispersion and colonization in the Mediterranean basin.…”

A genomewide catalogue of single nucleotide polymorphisms in white‐beaked and Atlantic white‐sided dolphins

“…Previous population genetic studies of both species have sequenced fragments of the mtDNA control region (Banguera‐Hinestroza et al . , ; Mirimin et al . ) and <15 microsatellite markers, which were either specifically designed for the white‐beaked dolphin (Banguera‐Hinestroza et al .…”

“…A previous phylogeographic survey identified three genetically differentiated populations (north‐west (NW) Atlantic, north Norwegian and North Celtic Seas) among 116 white‐beaked dolphins (Banguera‐Hinestroza et al . ). The haplotype diversity was found to be moderate using 323 bp of the mitochondrial D‐loop ( h = 0.7320 ± 0.00031).…”

“…The nucleotide diversity was low ( π = 0.56 ± 0.04%), possibly as a result of a recent demographic bottleneck resulting from human activities (ASCOBANS, ; Banguera‐Hinestroza et al . ). In contrast, no clear substructure was found between NW ( N = 88) and NE ( N = 267) Atlantic white‐sided dolphins (Banguera‐Hinestroza et al .…”