Regional differentiation and post-glacial expansion of the Atlantic silverside, Menidia menidia, an annual fish with high dispersal potential

Abstract

The coastal marine environment of the Northwest Atlantic contains strong environmental gradients that create distinct marine biogeographic provinces by limiting dispersal, recruitment, and survival. This region has also been subjected to numerous Pleistocene glacial cycles, resulting in repeated extirpations and recolonizations in northern populations of marine organisms. In this study, we examined patterns of genetic structure and historical demography in the Atlantic silverside, Menidia menidia, an annual marine fish with high dispersal potential but with well-documented patterns of clinal phenotypic adaptation along the environmental gradients of the Northwest Atlantic. Contrary to previous studies indicating genetic homogeneity that should preclude regional adaptation, results demonstrate subtle but significant (FST = 0.07; P < 0.0001) genetic structure among three phylogeographic regions that partially correspond with biogeographic provinces, suggesting regional limits to gene flow. Tests for non-equilibrium population dynamics and latitudinal patterns in genetic diversity indicate northward population expansion from a single southern refugium following the last glacial maximum, suggesting that phylogeographic and phenotypic patterns have relatively recent origins. The recovery of phylogeographic structure and the partial correspondence of these regions to recognized biogeographic provinces suggest that the environmental gradients that shape biogeographic patterns in the Northwest Atlantic may also limit gene flow in M. menidia, creating phylogeographic structure and contributing to the creation of latitudinal phenotypic clines in this species.Electronic supplementary materialThe online version of this article (doi:10.1007/s00227-010-1577-3) contains supplementary material, which is available to authorized users.

Going where traditional markers have not gone before: utility of and promise for RAD sequencing in marine invertebrate phylogeography and population genomics

“…; Williams & Oleksiak ) and Menidia menidia (Mach et al . ), both of which have overlapping ranges with N. vectensis, has also observed similar genetic diversity among populations along the Atlantic coast of North America. In these fish species, the absence of reduced diversity in higher‐latitude populations is in part a result of local adaptation along environmental clines and in response to anthropogenic stressors.…”

Spatial scale and divergent patterns of variation in adapted traits in the ocean

“…2010). Correspondingly, studies of molecular genetic variation (presumably neutral to selection) display a relatively weak structure consisting of three broad regions along the coast (Mach et al. 2011).…”

Practical low‐coverage genomewide sequencing of hundreds of individually barcoded samples for population and evolutionary genomics in nonmodel species

“…The first principle component separates the geographical samples along a north–south continuum, while PC 2 shows the distinctness of silversides from the Gulf of St. Lawrence, as has been reported from D‐loop sequence data (Mach et al . ). In addition, the PCA also reveals that a few individuals cluster with a different group than most other individuals collected at the same locations, indicating that they may be migrants.…”

“…This pattern is consistent with northward migration from southern refugia since the last glaciation, as has been previously suggested for this species based on D‐loop sequences (Mach et al . ). The full‐length mitochondrial genomes provide a much richer data set for detailed reconstruction of demographic history of this species.…”

“…A previous study that examined a 340‐bp fragment of the D‐loop in 1029 silversides found the same haplotype in 66% of their samples and most other haplotypes differing only by a single substitution (Mach et al . ). The full mitochondrial genomes of our 200 individuals collected over the same geographical cline differed on average by >40 nucleotides (Fig.…”