Garcia-Cisneros A et al. (2016), Low genetic diversity and recent demographic ex...

ECB-ART-44916

Sci Rep 2016 Sep 15;6:33269. doi: 10.1038/srep33269.

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Low genetic diversity and recent demographic expansion in the red starfish Echinaster sepositus (Retzius 1816).

Garcia-Cisneros A , Palacín C , Ben Khadra Y , Pérez-Portela R .

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Understanding the phylogeography and genetic structure of populations and the processes responsible of patterns therein is crucial for evaluating the vulnerability of marine species and developing management strategies. In this study, we explore how past climatic events and ongoing oceanographic and demographic processes have shaped the genetic structure and diversity of the Atlanto-Mediterranean red starfish Echinaster sepositus. The species is relatively abundant in some areas of the Mediterranean Sea, but some populations have dramatically decreased over recent years due to direct extraction for ornamental aquariums and souvenir industries. Analyses across most of the distribution range of the species based on the mitochondrial cytochrome c oxidase subunit I gene and eight microsatellite loci revealed very low intraspecific genetic diversity. The species showed a weak genetic structure within marine basins despite the a priori low dispersal potential of its lecithotrophic larva. Our results also revealed a very recent demographic expansion across the distribution range of the species. The genetic data presented here indicate that the species might be highly vulnerable, due to its low intraspecific genetic diversity.

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Species referenced: Echinodermata
Genes referenced: LOC100887844 LOC100893907 LOC576414 LOC577219 LOC590354

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References [+] :

Alberto, MsatAllele_1.0: An R package to visualize the binning of microsatellite alleles. 2009, Pubmed

	Figure 1. Haplotype network from COI sequences of E. sepositus.The area of the circles is proportional to the number of sampled individuals, and different colours represent different populations. Small red dashes represent mutation steps of more than one mutation. Asterisks (*) indicate non-synonymous mutations. The most common haplotypes, H_1, H_2 and H_3, are underlined using the colour pattern from Fig. 2.
	Figure 2. Map of the sampling locations in E. sepositus.Pie charts represent COI haplotype frequencies for each location, and size is proportional to the number of samples analysed. Private haplotypes are represented in purple. For location codes see Table 1. Red dotted lines represent the main marine barriers in the geographical area: the Almeria Oran Front (AOF) and the Siculo-Tunisian Strait. The map was drawn using Maps and Mapplots R packages and Inkscape v 0.48 (Free Software Foundation, Inc.; Boston, USA; http://inkscape.org).
	Figure 3. Bar plots of the Bayesian clustering analysis obtained using STRUCTURE for different K values.(A) Analysis based on microsatellite loci. (B) Analysis based on the combination of both mitochondrial sequences (COI) and microsatellite loci. Note that the same K values are presented, for comparison between databases.
	Figure 4. Multidimensional scaling (MDS) from the Jost’s D pairwise matrix computed from COI sequences.
	Figure 5. Multidimensional scaling (MDS) from pairwise Jost’s D differences from microsatellite data.
	Figure 6. Values of theta and migration between basins and sub-basins.Yellow circles represent the value of theta (logarithmically transformed) per basin, and arrows represent the direction of migration. The thickness of the arrows is proportional to the migration value. Values in brackets are the 95% HPD confidence of theta.
	Figure 7. Mismatch distribution of E. sepositus for all samples.Observed (Obs) and expected (Exp) values of the distribution are represented as dashed and solid lines, respectively.
	Figure 8. Bar plots representing diversity values from COI and microsatellites per basin.(A) Rarefied haplotype diversity, (B) nucleotide diversity, and (C) allelic richness. Black bars represent Atlantic populations (Atl), white bars western Mediterranean populations (W. Med), and grey bars eastern Mediterranean populations (E. Med).