The Decapoda - shrimp, lobsters, and crabs - are an economically important, diverse group of animals whose geologic history extends back 400 million years. Living representatives, numbering over 15,000 species, are global in distribution and nearly ubiquitous in oceanic and non-oceanic environments. They exert a major impact on ecosystems; understanding the dynamics of their fossil record will illuminate their historical impact on ecosystems. We will test the hypothesis that decapods are arrayed in a series of discrete evolutionary faunas; remarkably, the vast array of living and fossil decapods in diverse interrelated groups have exploited four basic body plans repeatedly. Other hypotheses to be tested are that the Decapoda have repeatedly adopted a limited number of baupläne, or generalized architectures, throughout their history; that they have experienced explosive evolutionary radiations followed by periods of no determinable change; and that they are generally resistant to mass extinction events. These hypotheses will be tested using a unique dataset compiled and assessed by the Principle Investigators: a compilation of all fossil decapod species, arrayed in a classification scheme including fossil and living taxa, with geologic and geographic ranges of all species, including a phylogeny (i.e. "family tree") for many sub-groups within the Decapoda. The dataset will be expanded to include ecological data for each taxon and will be entered into the Paleobiology Database, an NSF-supported vehicle for analyzing the fossil record. Employing its methodology, patterns of diversity and macroevolution of the decapods will be generated at levels ranging from the entire Order to species level. This will result in a comprehensive analysis of macroevolutionary patterns of this major group for the first time. Available paleoecological data derived from field studies and published records will be used to determine the effects of various environmental factors such as seafloor conditions, reef development, water depth, and temperature on morphology, extinction survivorship, and diversity. Because decapods have a remarkable range of morphological variation preservable in the fossil record, the diversity of the groups of decapods can be assessed in relation to their morphological characteristics. Defining the history of taxa with specialized morphology will permit recognition of body plans that have been exploited by different decapod groups throughout the history of the clade.
Intellectual merit. This study will provide the most comprehensive analysis of macroevolution of the Decapoda yet conducted, all based upon a unique dataset that is internally consistent by virtue of its having been developed entirely by the investigators. It will document the significance of employing a high resolution, species-level database for interpretation of diversity. The hypotheses and conclusions derived here will provide a model and the foundation for future work on Decapoda, Arthropoda, and macroevolution of well-constrained groups. It will provide a test for the efficacy of PBDB data versus a constrained dataset assessed by specialist systematists.
Broader impacts. The work will introduce undergraduate students at Kent State at Stark, an undergraduate campus, and Kent State at Kent, to research that involves paleoecological, paleogeographical, and functional morphological elements which, in turn, will be communicated to other students. Because decapods are known to virtually everyone, they form an excellent group to use to inform the public about ancient patterns of diversity and the relationship between the morphology of organisms, variations in their environmental requirements, and their adaptability to different physical conditions. This will be conveyed in a professionally constructed display which has the potential to be exhibited in museums and universities around the country. Small kits designed for use in elementary and middle schools will be available to allow students to make their own observations about the adaptations of decapods to their environment and its effect on diversity. Published papers and presentations on results of research at meetings will be prepared throughout the course of the research. Because the study of modern biodiversity is a concern of the general public, presentations to broader audiences as well as geology classes will provide a broad historical context for understanding modern patterns of diversity. Data entered into Paleobiology Database and Ohio Data Resource Commons will be openly available to other researchers and the general public. Combined, the databases will assure archival storage and public access, following a proprietary period.
