Data from: Phylogeography of the snake pipefish, Entelurus aequoreus (Family: Syngnathidae) in the northeastern Atlantic Ocean

The snake pipefish, Entelurus aequoreus, is a widespread marine species
occurring in pelagic and coastal environments in the northeastern Atlantic
Ocean. Recently, the snake pipefish underwent a short-lived, yet
substantial, increase in abundance and range expansion into arctic waters.
However, little is known about the species’ population structure or if
different ecotypes contributed to this outbreak. Specimens (n=178) were
sampled from 25 locations from six regions spanning 1.9 million km2. A
fragment of the mitochondrial cytochrome b gene and control region was
used to assess population structure and genetic diversity. Both loci
showed high haplotype diversity (Hd) and low nucleotide diversity (π) over
all sampled locations. A genetic signature of population expansion was
evident through mismatch distributions and tests for recent population
expansion (Fu’s Fs, Tajima’s D, and R2). Effective population size
analyses (Bayesian Skyline Plot) suggest an ancient expansion (50-100
thousand years ago). However, we found neither significant population
differentiation (AMOVA) among regions, nor evidence of genetically
distinct ecotypes. This lack of structure is likely due to a pelagic life
style, fast development and long distance dispersal aided by ocean
currents. Our work highlights the need for further research to better
understand the recent outbreak and how this species may respond to future
environmental challenges.