Phylogenetic Relationships and Skeletomuscular Evolution of the Arachnids

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9615526 SHULTZ Arthropods (spiders, crabs, insects and their relatives) have a long and complex history (phylogeny), and the greatest diversity in shape and form of all the animal groups. In order to better understand how these complex, and often economically important, animals actually work, it is important to know how they are put together; it is especially important to know how muscles are attached to the hardened outer surface (exoskeleton) of each animal, forming Oskeletomuscular complexesO that permit the animals to move, feed, and reproduce. Certain skeletomuscular complexes may have occurred only once in the histories of arthropods; others, which may look alike and function in a similar way, may have appeared in several different places in the arthropod phylogenetic tree. However, since not enough information has yet been obtained to determine the true phylogeny of arthropod groups, it is, at present, difficult to assess whether particular skeletomuscular complexes appeared once or more than once in arthropod history. In this study, Jeffrey W. Schultz will examine the details of skeletomuscular complex structures in a major group of arthropods, the arachnids (spiders, scorpions, mites and their relatives). He will use skeletomuscular characters, both alone and with molecular sequence data, to reconstruct the phylogeny of the arachnids, and will then use the phylogeny to estimate when, how, and how often particular skeletomuscular complexes appeared in arachnids, and how these complexes changed, in form and function, throughout the history of these animals. It is expected that this analysis will solve long-standing problems in the phylogeny and evolutionary morphology of an important group of arthropods.