Molecular Analysis of Morphologically Defined Taxa in the Montastraea Annularis Complex

如果不能准确地定义和识别物种，就会从根本上损害我们理解和管理海洋生态系统的能力。这一问题在珊瑚礁上尤其严重，因为在那里，对构成许多重要珊瑚群的许多生态和形态上不同的“形式”的物种地位没有达成共识。虽然人们普遍认识到珊瑚物种的问题性质，但对于为什么会存在这一问题却没有达成共识。 一些科学家认为，广泛而复杂的杂交模式使珊瑚的物种边界任意，但测试这一论断的数据在很大程度上缺乏，特别是加勒比海珊瑚。 在这个项目中，诺尔顿博士和合作者将利用星星珊瑚Montastraea annularis作为模型系统来解决这个问题。这种珊瑚是加勒比海最丰富的珊瑚，已经有数百万年的历史了。生物学家和地质学家将其作为一种“实验鼠”进行了广泛的研究（例如珊瑚漂白、古气候学），但最近的结果表明，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，这些形式可以通过其群体形态来识别。 以前的工作是关于珊瑚遗传学，共生，形态测量学和生殖生物学，但广泛的地理尺度上的遗传模式具有根本的重要性。 如果组成Montastraea annularis的三个分类群不经常杂交，那么原则上应该可以检测到固定的诊断差异。 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和其他两个类群。到目前为止，她还没有发现M. annularis和M. franksi，但它们似乎在整个分布区的不同时间产卵，这表明它们的基因并不相同。 在这个项目中，她将继续筛选这些类群之间的遗传差异，以确定M。faveolata和其他分类群之间的差异，并看看是否更广泛的搜索将揭示M。annularis和M.弗兰克 她还将把遗传分析从巴拿马扩展到加勒比地区的其他地点，以确定在这里观察到的模式是否也在其他地方看到。这将是第一次对整个地理范围内的珊瑚礁物种复合体进行此类遗传分析。

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.