Genetic structure of the high dispersal Atlanto-Mediterreanean sea star Astropecten aranciacus revealed by mitochondrial DNA sequences and microsatellite loci

Abstract

Genetic structure of the high dispersal Atlanto-Mediterreanean sea star Astropecten aranciacus revealed by mitochondrial DNA sequences and microsatellite loci AbstractTo investigate the impact of potential marine barriers on gene-flow in high dispersal marine invertebrates, we assessed the population genetic structure of the sea star Astropecten aranciacus. Samples were obtained from nine locations within the Atlantic and the Mediterranean Sea including populations east of the Siculo-Tunisian Strait. We obtained both DNA sequence data of the mitochondrial control region and genotype data at four microsatellite loci. Both markers were highly polymorphic and showed a great level of genetic diversity. Genetic differentiation between populations (F (ST)) was in general low, particularly for nuclear data, as is often the case in high dispersal marine invertebrates. Nevertheless, both marker sets indicated a significant genetic differentiation of the population from the island of Madeira to most other populations. Our results also demonstrate a clear pattern of isolation-by-distance supported by both mitochondrial and nuclear markers. Therefore, we conclude that larval dispersal of A. aranciacus is somewhat limited even within the basins of the Atlantic, the west Mediterranean and the east Mediterranean. Microsatellite loci further revealed genetic differentiation between the three basins; however, it is not clear whether this is truly caused by marine barriers. Genetic differentiation between basins might also be a result of isolation-by-distance allowing for any grouping to be significant as long as geographical neighbors are clustered together. Although levels of genetic differentiation were less pronounced in mirosatellite data, both datasets were coherent and revealed similar patterns of genetic structure in A. aranciacus. 1Genetic structure of the high dispersal Atlanto-Mediterreanean sea star Astropecten aranciacus revealed by mitochondrial DNA sequences and microsatellite loci Deborah E. Zulliger, Samuel Tanner, Markus Ruch and Georg Ribi AbstractTo investigate the impact of potential marine barriers on gene flow in high dispersal marine invertebrates, we assessed the population genetic structure of the sea star Astropecten aranciacus. Samples were obtained from nine locations within the Atlantic and the Mediterranean Sea including populations east of the Siculo-Tunisian Strait. We obtained both DNA sequence data of the mitochondrial control region and genotype data at four microsatellite loci. Both markers were highly polymorphic and showed a great level of genetic diversity. Genetic differentiation between populations (F ST ) was in general low, particularly for nuclear data, as is often the case in high dispersal marine invertebrates. Nevertheless, both marker sets indicated a significant genetic differentiation of the population from the island of Madeira to most other populations. Our results also demonstrate a clear pattern of isolation-by-distance supported by both mitochondrial and nuclear markers. The...

Phylogeography of the sea star Marthasterias glacialis (Asteroidea, Echinodermata): deep genetic divergence between mitochondrial lineages in the north-western mediterranean

“…The absence of population subdivision at both sides of the Gibraltar Strait strongly contrasts with population differentiation patterns across the AtlantoMediterranean transition described for a number of marine invertebrate species (see Borsa et al 1997;Patarnello et al 2007). Although discrepancies between population genetic patterns for high dispersal echinoderms between Atlantic and Mediterranean sea suggest that similar biological features do not necessarily imply similar population structure (Calderon et al 2008;Muths et al 2009;Zulliger et al 2009), a number of the marine invertebrate species analysed demonstrated either a common pattern of ''genetic divergence'' at both sides of this Strait or isolation by distance (see e.g. Quesada et al 1995;Zane et al 2000;Pérez-Losada et al 2002).…”

“…A bimodal distribution detected for the Mediterranean area emerges from grouping together two genetic pools holding different demographic history. Unimodal distributions in other marine invertebrates have been related to episodes of sea level oscillations during the Pleistocene and prior to the last glacial maximum 18,000 years ago (Zulliger et al 2009;Couceiro et al 2007). According to our results, a rapid population expansion after a glacial period would explain the present diversity of the species (Avise et al 1984).…”

“…For instance, the high dispersal sea urchin Paracentrotus lividus showed a sharp break between populations at both sides of the AOF, as well as a higher genetic diversity in Mediterranean populations (Calderon et al 2008). However, for the broadcast spawner Astropecten aranciacus, populations seemed to be isolated by distance but genetic divergences were not related with a gene flow interruption between basins (Zulliger et al 2009). …”

“…A number of studies on the phylogeography of marine invertebrates have been carried out at both sides of the Bass Strait that separates eastern from southern Australia (Waters and Roy 2003), the Bass Strait between South America and the Antarctic Peninsula (Hunter and Halanych 2008) and the Gibraltar Strait (Zulliger et al 2009), which is the only connection between the Atlantic Ocean and the Mediterranean Sea and measures less than 11 miles wide. In the case of the AtlantoMediterranean transition, the Almeria-Oran Front (AOF) located inside the Mediterranean has been defined as the main boundary between Atlantic and Mediterranean surface waters, but the transition at the biological level still remains controversial (Borsa et al 1997;Cimmaruta et al 2005;Patarnello et al 2007) and marine species display different patterns of genetic structure at both sides of this particular area (e.g.…”

Genetic architecture of the marbled goby Pomatoschistus marmoratus (Perciformes, Gobiidae) in the Mediterranean Sea

“…For instance, the differentiation of the sea star Astropecten aranciacus in the Mediterranean Sea is the result of an isolation-by-distance pattern, which allowed for any grouping to be significant. This occurs provided that geographical neighbours are clustered together and without there being a strong discrepancy between samples collected in the northern Adriatic and Aegean sub-basins (Zulliger et al, 2009). Many other examples derive from the population structure of Mediterranean pelagic species, which do not mirror palaeo-oceanographic events to such an extent.…”