9725273 Budd More than 60% of the modern Caribbean reef coral fauna arose between 4-1.5 Ma during an episode of accelerated faunal turnover, documented as part of previous NSF funded research. The proposed research shifts from a taxonomically broad characterization of this episode to an in-depth analysis of some of its most important participants, and focuses on morphologic evolution within a clade of Montastraea. The selected clade has been ecologically dominant for the past 30 myr and consists of at least 10 species. Among them are members of the modern Montastraea annularis species complex, which arose early during the turnover episode and have widely been used as a model organism in marine ecology and geology; e.g., to study coral beaching and paleoclimatic change. The complex has long been thought to represent one species, whose colony morphology varied extensively in response to light at different reef depths. However, Knowlton & co-workers have recently used reproductive and molecular data and field studies of colony morphology to propose that M. 'annularis' is actually a complex of at least 3 species. A pilot study with Knowlton has shown that, although the 3 species overlap in traditional morphologic characters, they are clearly distinct in morphometric analyses of non-traditional characters including: (1) the 3D relief of septa on calical surfaces and (2) the 2D structure of the corallite walls. Moreover, evolutionary relationships inferred from 3D morphometric results correspond with those based on DNA. These findings suggest that the evolutionary study of faunal turnover may be compromised by the inadequacy of traditional procedures to consistently recognize genetically distinct species. The proposed research will therefore develop more refined morphometric methods for recognizing species in the fossil record and tracing their evolution through geologic time. It involves: (1) conducting a survey of morphologic characters using 3D morphometrics to determine which char acters best match the results of ongoing DNA work by Knowlton & co-workers; (2) devising a procedure based on a subset of the characters above, which can be used to recognize species in fossil material and trace them through geologic time; (3) examining the morphologic stability of these species at intervals of < 100 kyr through series of Late Pleistocene reef terraces at scattered geographic locations; (4) Reconstructing the phylogeny of the clade using combined morphometrics & phylogenetic approaches. In the first 2 sets of analyses, I will collaborate with Nancy Knowlton, and in the third, with John Pandolfi. Except for field and shipping expenses, Knowlton & Pandolfi are funded separately by the Smithsonian Institution. The material will consist of genetically characterized colonies (provided by Knowlton); newly collected, ecologically characterized Late Pleistocene colonies (collected with Pandolfi); and well-dated Oligocene to Early Pleistocene in museum collections, most of which I made as part of earlier NSF funded work. The results will be used: (1) to document the timing and pattern of speciation and extinction events within the M. annularis complex, and relate them to patterns of overall faunal turnover, and (2) to examine trends of morphologic evolution at various levels within the clade and interpret their cause. They will thus contribute valuable information for assessing the roles of external environmental factors and biological interactions in causing turnover. The proposed research will provide an elegant model system, integrating molecular, reproductive, morphologic, and fossil data in an ecologically important but manageable size clade. It will be the first such system in reef corals to incorporate fossil data and use them for inferring evolutionary processes. In addition to paleontology, the proposed research will contribute in important ways to coral reef biology, systematics, and molecular evolution. Interpretation of modern distributions will be aided by eval uation of the past ecological roles of these species, new morphological techniques for reliably separating closely related species will be developed, and the combination of fossil and molecular data will provide the first estimates in corals for rates of molecular evolution for relatively recently diverged taxa. Funds are requested for image analysis equipment; salary for a grad student R.A. & the PI; field work collecting Late Pleistocene colonies; and the use of university SEM & confocal microscopes.
