Molecular Analysis of Morphologically Defined Taxa in the Montastraea Annularis Complex

不能准确地定义和识别物种从根本上损害了我们理解和管理海洋生态系统的能力。这个问题在珊瑚礁上尤为严重，在珊瑚礁上，人们对组成许多重要珊瑚群的众多生态和形态不同的“形式”的物种状况没有达成共识。虽然人们普遍认识到珊瑚物种的问题性质，但对于这个问题存在的原因却没有达成共识。一些科学家认为，广泛而复杂的杂交模式使珊瑚的物种界限变得任意，但验证这一断言的数据在很大程度上缺乏，特别是对加勒比海的珊瑚。在这个项目中，诺尔顿博士和合作者将利用星珊瑚——环状蒙塔斯特拉（Montastraea annularis）作为模型系统来解决这个问题。这种珊瑚是加勒比地区最丰富的珊瑚，已经存在了数百万年。它已经被生物学家和地质学家作为一种“实验室老鼠”进行了广泛的研究（例如珊瑚白化，古气候学），但最近的研究结果表明，曾经被视为单一多态物种的物种可能代表了至少三种生殖隔离形式的复合体，可以通过它们的群体形态来识别。以前的工作是关于珊瑚遗传学、共生、形态计量学和生殖生物学，但在广泛的地理尺度上的遗传模式是至关重要的。如果组成环形蒙塔斯特拉的三个分类群不经常杂交，那么固定的诊断差异原则上应该是可以检测到的。诺尔顿博士已经利用扩增片段长度多态性（AFLP）和限制性片段长度多态性（RFLP）发现了M. faveolata和其他两个分类群之间的一些固定或接近固定的差异。到目前为止，她还没有发现环状分枝杆菌和弗兰克分枝杆菌之间存在固定的基因差异，但它们似乎在不同的时间产卵，这表明它们在基因上并不相同。在这个项目中，她将继续筛选这些分类群之间的遗传差异，以确定是否可以检测到M. faveolata和其他分类群之间的杂交，并看看是否更广泛的搜索将揭示M. annularis和M. fransi之间的差异。她还将把遗传分析从巴拿马扩展到加勒比海的其他地点，以确定这里观察到的模式是否也在其他地方出现。这将是首次对整个地理范围内的珊瑚礁珊瑚物种进行遗传分析。

Failure to accurately define and identify species fundamentally compromises our ability to understand and manage marine ecosystems. The problem is particularly acute on reefs, where there is no consensus on the species status of the numerous ecologically and morphologically distinct `forms` that comprise many important groups of corals. While the problematic nature of coral species is widely recognized, there is no consensus as to why this problem exists. Some scientists argue that extensive and complex patterns of hybridization make species boundaries arbitrary in corals, but the data to test this assertion are largely lacking, particularly for Caribbean corals. In this project, Dr. Knowlton and collaborators will tackle this problem using the star coral, Montastraea annularis, as a model system. This coral is the most abundant coral of the Caribbean, and has been for millions of years. It has been extensively studied by biologists and geologists as a kind of `lab rat` for a wide variety of studies (e.g. coral bleaching, paleoclimatology), but recent results suggest that what had been viewed as a single polymorphic species may represent a complex of at least three reproductively isolated forms that can be identified by their colony morphologies. Previous work was on coral genetics, symbiosis, morphometrics and reproductive biology but the genetic patterns on wide geographic scales are of fundamental importance. If the three taxa comprising Montastraea annularis do not routinely interbreed, then fixed diagnostic differences should in principle be detectable. Dr. Knowlton has already uncovered a few fixed or nearly fixed differences using amplified fragment length polyinorphism (AFLP) and restriction fragment length polymorphism (RFLP) between M. faveolata and the other two taxa. She has as yet found no fixed genetic differences between M. annularis and M. franksi, but they appear to spawn at distinct times throughout their range, suggesting that they are not genetically identical. In this project, she will continue to screen for genetic differences among these taxa, in order to determine if hybrids between M. faveolata and the other taxa can be detected and to see if more extensive searches will reveal differences between M. annularis and M. franksi. She will also extend the genetic analyses from Panama to other sites in the Caribbean, to determine if the patterns observed here are also seen elsewhere. This will be the first such genetic analysis of a reef coral species complex throughout its geographic range.