Mitochondrial DNA panmixia in the little brown seastar Echinaster spinulosus suggests a recent population expansion

Abstract

In North America, the Atlantic-Gulf discontinuity depicts genetic breaks between populations distributed along the Florida peninsula. This study examines 83 specimens of E. spinulosus obtained from seven locations along the Florida coast to examine phylogeographic patterns, population structure and examine historical demographic patterns. Analyses of 511 bp from the cytochrome oxidase 1 (COI) mitochondrial gene inferred no significant genetic structure for E. spinulosus along either side of the Florida coast nor was there a genetic discontinuity associated with a “Gulf-Atlantic” split. Population-based statistical analyses revealed no significant degree of genetic differentiation (Fst, p < 0.05) among populations, thus indicating substantial gene flow. Similarly, summary statistics (Fu’s Fs, mismatch distributions) were significant indicating that there has been a population increase in the recent past. Recent range expansion, possibly due to a leading edge effect, combined with some level of contemporary larval mixing seems to be the main source of panmixia in this species.

Keywords:

• Echinaster spinulosus
• mitochondrial DNA
• panmixia
• population expansion

Acknowledgements

This work would not have been possible without the assistance in the collection and donation of samples from, John Lawrence, Jennifer Walker, Kathryn Perez, Chris Denson, Larry Thompson, David Campbell, Jeff Pollock, Mark Siddall, Greg Reeder, Andrew Hendricks, Tom Hopkins, and the crew of the R/V Bellows.

Declaration of interest

The author reports no conflicts of interest. The author alone is responsible for the content and writing of the paper. This work was funded by grants from the Lerner Gray Fund for Marine Research, University of Alabama Tanglewood Research Grant, Morehead State University and Eastern Kentucky University.