Pelagic life and depth: coastal physical features in West Africa shape the genetic structure of the Bonga Shad, Ethmalosa fimbriata

• Published in: PloS one 2013-10, Vol.8 (10), p.e77483-e77483
• Main Authors: Durand, Jean-Dominique, Guinand, Bruno, Dodson, Julian J, Lecomte, Frédéric
• Format: Article
• Language: English
• Subjects: Africa, Western; Animal genetics; Animal Migration; Animals; Anthropogenic factors; Bayes Theorem; Bayesian analysis; Biodiversity; Canyons; Case studies; Coastal ecology; Coasts; Commercial fishing; Connectivity; Data processing; Deep water; Deoxyribonucleic acid; DNA; DNA - genetics; DNA - isolation & purification; Ecosystem; Ecosystems; Environmental degradation; Ethmalosa fimbriata; Exploitation; Fish; Fisheries management; Fishes - genetics; Fishing; Gene Flow; Genetic diversity; Genetic markers; Genetic structure; Genetic Variation; Genetics; Genetics, Population; Habitats; Human influences; Identification methods; Life Sciences; Markers; Mitochondria; Mitochondrial DNA; Phylogeography; Population; Populations and Evolution; Pressure; Refuges; Regional analysis; Shorelines; Spatial distribution; Species; Species diversity; Statistical inference; Studies
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0077483

The bonga shad, Ethmalosa fimbriata, is a West African pelagic species still abundant in most habitats of its distribution range and thought to be only recently affected by anthropogenic pressure (habitat destruction or fishing pressure). Its presence in a wide range of coastal habitats characterised by different hydrodynamic processes, represents a case study useful for evaluating the importance of physical structure of the west African shoreline on the genetic structure of a small pelagic species. To investigate this question, the genetic diversity of E. fimbriata was assessed at both regional and species range scales, using mitochondrial (mt) and nuclear DNA markers. Whereas only three panmictic units were identified with mtDNA at the large spatial scale, nuclear genetic markers (EPIC: exon-primed intron-crossing) indicated a more complex genetic pattern at the regional scale. In the northern-most section of shad's distribution range, up to 4 distinct units were identified. Bayesian inference as well as spatial autocorrelation methods provided evidence that gene flow is impeded by the presence of deep-water areas near the coastline (restricting the width of the coastal shelf), such as the Cap Timiris and the Kayar canyons in Mauritania and Senegal, respectively. The added discriminatory power provided by the use of EPIC markers proved to be essential to detect the influence of more subtle, contemporary processes (e.g. gene flow, barriers, etc.) acting within the glacial refuges identified previously by mtDNA.