Zhan Aibin, Hu Jingjie, Hu Xiaoli, Zhou Zunchun, Hui Min, Wang Shi, Peng Wei, Wang Mingling, Bao Zhenmin
Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, 266003, People's Republic of China.
Mar Biotechnol (NY). 2009 Mar-Apr;11(2):223-35. doi: 10.1007/s10126-008-9138-1. Epub 2008 Sep 3.
Marine scallops, with extended planktonic larval stages which can potentially disperse over large distances when advected by marine currents, are expected to possess low geographical differentiation. However, the sessile lifestyle as adult tends to form discrete "sea beds" with unique population dynamics and structure. The narrow distribution of Zhikong scallop (Chlamys farreri), its long planktonic larval stage, and the extremely hydrographic complexity in its distribution range provide an interesting case to elucidate the impact of marine currents on geographical differentiation for marine bivalves at a fine geographical scale. In this study, we analyzed genetic variation at nine microsatellite DNA loci in six locations throughout the distribution of Zhikong scallop in the Northern China. Very high genetic diversity was present in all six populations. Two populations sampled from the same marine gyre had no detectable genetic differentiation (F (ST) = 0.0013); however, the remaining four populations collected from different marine gyres or separated by strong marine currents showed low but significant genetic differentiation (F (ST) range 0.0184-0.0602). Genetic differentiation was further analyzed using the Monmonier algorithm to identify genetic barriers and using the assignment test conducted by software GeneClass2 to ascertain population membership of individuals. The genetic barriers fitting the orientation of marine gyres/currents were clearly identified, and the individual assignment analysis indicated that 95.6% of specimens were correctly allocated to one of the six populations sampled. The results support the hypothesis that significant population structure is present in Zhikong scallop at a fine geographical scale, and marine currents can be responsible for the genetic differentiation.
海洋扇贝具有较长的浮游幼虫阶段，当被海流输送时，有可能远距离扩散，预计其地理分化程度较低。然而，成年扇贝的固着生活方式往往会形成具有独特种群动态和结构的离散“海床”。栉孔扇贝（Chlamys farreri）分布范围狭窄，浮游幼虫阶段长，且其分布范围内水文状况极为复杂，这为在精细地理尺度上阐明海流对海洋双壳贝类地理分化的影响提供了一个有趣的案例。在本研究中，我们分析了中国北方栉孔扇贝分布区六个地点九个微卫星DNA位点的遗传变异。所有六个种群都存在非常高的遗传多样性。从同一海洋环流中采样的两个种群没有检测到遗传分化（F(ST)=0.0013）；然而，从不同海洋环流或被强大海流隔开的其余四个种群显示出低但显著的遗传分化（F(ST)范围为0.0184 - 0.0602）。使用Monmonier算法进一步分析遗传分化以识别遗传屏障，并使用软件GeneClass2进行的赋值测试来确定个体的种群归属。明确识别出了与海洋环流/海流方向相符的遗传屏障，个体赋值分析表明95.6%的标本被正确分配到所采样的六个种群之一。结果支持了这样的假设，即在精细地理尺度上栉孔扇贝存在显著的种群结构，并且海流可能是遗传分化的原因。
