Genetic structure of giant clam (Tridacna maxima) populations in the west Pacific is not consistent with dispersal by present-day ocean currents
Genetic structure of giant clam (Tridacna maxima) populations in the west Pacific is not consistent with dispersal by present-day ocean currents
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DOI：
10.1111/j.1558-5646.1997.tb03660.x
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发表时间：
1997-06-01
期刊：
影响因子：
3.3
通讯作者：
Williams, ST
中科院分区：
文献类型：
--
作者：
Benzie, JAH;Williams, ST
太平洋海洋生物群，特别是浮游幼虫阶段较长的物种，被认为通过洋流广泛分布在整个太平洋。迄今为止，可用的遗传数据很少，支持了这一观点，因为在较大的地理距离内，很少或没有发现显着的人口区域差异。然而，最近来自巨蛤的数据不仅表明了种群的显着区域差异，而且还表明了与当今主要洋流垂直的基因流动路线。对整个西太平洋和中太平洋的 19 个砗磲种群的 8 个多态位点的遗传变异进行了广泛的调查，证实了迄今为止在砗磲中发现的变异模式并非该物种所独有，并且可能反映了浅水海洋类群的基本遗传结构。像大堡礁这样高度连通的珊瑚礁系统中的巨型砗磲种群是泛混的（平均F-ST < 0.003），但不同群岛的珊瑚礁群之间（平均F-ST = 0.084）以及西太平洋和中太平洋地区之间（平均F-ST = 0.156）之间发现了高度显着的遗传差异。推断的基因在菲律宾和大堡礁之间、菲律宾和美拉尼西亚（所罗门群岛和斐济）之间以及菲律宾和中太平洋岛屿群（马绍尔群岛、基里巴斯、图瓦卢和库克群岛）之间飞行的频率很高（N(c)m通常> 5）。这三组岛链之间的基因流较低（N(c)m < 2）。这些基因流动路线垂直于当今的洋流。有人认为，基因频率的空间模式反映了过去海平面较低时期的扩散事件，而这些事件并未被当前环流的后续扩散所消除。这些模式与太平洋海洋物种的广泛扩散以及印度-马来地区扩散的传统观点一致。然而，他们证明，不能假设沿着当今海洋表面流的扩散，今天可能有其他机制在起作用，或者主要的扩散事件是间歇性的（可能相隔数千年），而且太平洋海洋物种扩散的性质和时间比人们想象的更加复杂。
The Pacific marine biota, particularly species with long planktonic larval stages, are thought to disperse widely throughout the Pacific via ocean currents. The little genetic data available to date has supported this view in that little or no significant regional differentiation of populations has been found over large geographical distances. However, recent data from giant clams has demonstrated not only significant regional differentiation of populations, but routes of gene flow that run perpendicular to the main present-day ocean currents. Extensive surveys of genetic variation at eight polymorphic loci in 19 populations of the giant clam Tridacna maxima, sampled throughout the West and Central Pacific, confirmed that the patterns of variation seen so far in T. gigas were not unique to that species, and may reflect a fundamental genetic structuring of shallow-water marine taxa. Populations of T. maxima within highly connected reef systems like the Great Barrier Reef were panmictic (average F-ST < 0.003), but highly significant genetic differences between reef groups on different archipelagos (average F-ST = 0.084) and between West and Central Pacific regions (average F-ST = 0.156) were found. Inferred gene flew was high (N(c)m usually > 5) between the Philippines and the Great Barrier Reef, between the Philippines and Melanesia (the Solomon Islands and Fiji), and between the Philippines and the Central Pacific island groups (Marshall Islands, Kiribati, Tuvalu and Cook Islands). Gene flow was low between these three sets of island chains (N(c)m < 2). These routes of gene flow are perpendicular to present-day ocean currents. It is suggested that the spatial patterns of gene frequencies reflect past episodes of dispersal at times of lower sea levels which have not been erased by subsequent dispersal by present-day circulation. The patterns are consistent with extensive dispersal of marine species in the Pacific, and with traditional views of dispersal from the Indo-Malay region. However, they demonstrate that dispersal along present-day ocean surface currents cannot be assumed, that other mechanisms may operate today or that major dispersal events are intermittent (perhaps separated by several thousands of years), and that the nature and timing of dispersal of Pacific marine species is more complex than has been thought.