Department of Evolutionary Biology, Ecology and Environmental Sciences, University of Barcelona, Research Institute of Biodiversity (IRBIO), Barcelona, Spain.
Center for Advanced Studies of Blanes (CEAB-CSIC), Accès a la Cala Sant Francesc, Girona, Spain.
Mol Ecol. 2018 Feb;27(3):752-772. doi: 10.1111/mec.14454. Epub 2018 Jan 19.
Intraspecific genetic diversity and divergence have a large influence on the adaption and evolutionary potential of species. The widely distributed starfish, Coscinasterias tenuispina, combines sexual reproduction with asexual reproduction via fission. Here we analyse the phylogeography of this starfish to reveal historical and contemporary processes driving its intraspecific genetic divergence. We further consider whether asexual reproduction is the most important method of propagation throughout the distribution range of this species. Our study included 326 individuals from 16 populations, covering most of the species' distribution range. A total of 12 nuclear microsatellite loci and sequences of the mitochondrial cytochrome c oxidase subunit I (COI) gene were analysed. COI and microsatellites were clustered in two isolated lineages: one found along the southwestern Atlantic and the other along the northeastern Atlantic and Mediterranean Sea. This suggests the existence of two different evolutionary units. Marine barriers along the European coast would be responsible for population clustering: the Almeria-Oran Front that limits the entrance of migrants from the Atlantic to the Mediterranean, and the Siculo-Tunisian strait that divides the two Mediterranean basins. The presence of identical genotypes was detected in all populations, although two monoclonal populations were found in two sites where annual mean temperatures and minimum values were the lowest. Our results based on microsatellite loci showed that intrapopulation genetic diversity was significantly affected by clonality whereas it had lower effect for the global phylogeography of the species, although still some impact on populations' genetic divergence could be observed between some populations.
种内遗传多样性和分化对物种的适应和进化潜力有很大影响。分布广泛的海星 Coscinasterias tenuispina 通过分裂进行有性繁殖和无性繁殖的结合。在这里，我们分析了这种海星的系统地理学，以揭示历史和当代过程驱动其种内遗传分化。我们进一步考虑无性繁殖是否是该物种分布范围内最重要的繁殖方式。我们的研究包括来自 16 个种群的 326 个个体，涵盖了该物种的大部分分布范围。总共分析了 12 个核微卫星位点和线粒体细胞色素 c 氧化酶亚基 I（COI）基因的序列。COI 和微卫星在两个孤立的谱系中聚类：一个在西南大西洋发现，另一个在东北大西洋和地中海发现。这表明存在两个不同的进化单元。欧洲沿海的海洋屏障是导致种群聚类的原因：限制从大西洋进入地中海的移民的阿尔梅里亚-奥兰前线，以及分隔两个地中海盆地的西西里-突尼斯海峡。在所有种群中都检测到相同的基因型，尽管在两个年平均温度和最低温度最低的地点发现了两个单克隆种群。我们基于微卫星位点的结果表明，种内遗传多样性受到克隆性的显著影响，尽管对物种的全球系统地理学影响较小，但仍可观察到一些种群之间的遗传分化。
