Systematics and diversification of Old World shrews

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We are investigating the species-level diversity, phylogenetic relationships, and history of diversification of shrews from Asia and Africa. This work has been funded by the U.S. National Science Foundation through their international (OISE-0965856) and systematics programs (DEB-1343517). Old world shrews are a diverse (~240 species) group of small mammals with a highly conserved morphology. Their limited variation in morphology has made traditional approaches to taxonomy especially challenging and most molecular studies of this group find problems with morphologically defined species. We are therefore attempting to improve upon the current taxonomic resolution by emphasizing multilocus coalescent methods of delimiting species and estimating relationships. Our work on this project involves field-based inventories of shrews, and assessments of morphological and genetic variation. Recent publications include resolution of issues among the shrews of Java, the Philippines, and Tanzania. Project collaborators include Anang Achmadi and Maharadatunkamsi from the Indonesian Research Center for Biology, Kevin Rowe at Museum Victoria, and Bill Stanley, Julian Kerbis Peterhans, and John Bates at the Field Museum of Natural History.. The photograph shows Crocidura grayi, a white-toothed shrew endemic to Luzon Island, Philippines.

Building a better mammal tree of life

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With funding from NSF DEB-1441634, VertLife Terrestrial is a collaborative effort involving partners at Yale, University of Florida, UC Berkeley, and George Washington University. Our goals are to advance knowledge of phylogenetic relationships among tetrapods, while improving the availability of on-line resources that quantify phylogenetic and trait information. More specifically, we are adding unrepresented taxa to existing phylogenetic frameworks and we are incorporating trait data into existing databases, such as the Map of Life. At LSU, we are sequencing 1000s of loci in mammalian species that have not have not been included in previous phylogenetic estimates. Much of this effort relies on DNA extracted from dried museum skins that were collected prior to the regular preservation of frozen tissues. Ultimately, this project will provide better information on the relationships among tetrapod species, while generating critical tools for studying macroevolution, biogeography, and conservation biology.

Diversification of Sulawesi's rodent fauna

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I am currently collaborating with several folks, including Anang Achmadi and Kevin Rowe, on an investigation of the diversification patterns in Sulawesi's remarkable radiation of murine rodents. Sulawesi is a large island in central Indonesia with a complex history; it was once an archipelago, but the various paleo-islands have accreted over the last several millions of years. Diversity of rats and mice on the island is very high with nearly 50 species and 14 genera known thus far. We are interested in learning the extent to which in situ and ex situ diversification have contributed to this diversity and we're beginning to look at the tempo at which morphological diversity has arisen in this group. This will provide insights on the role of ecological opportunity in shaping the diversification of species and ecologically relevant variables such as morphology and habitat preferences. Completing this research will require continued surveys of Sulawesi's fauna, which is resulting in the discovery of several unknown species, including such oddities as a nearly toothless shrew-rat (Paucidentomys). This work is currently funded by the National Geographic Society and the Australia & Pacific Science Foundation. Pictured is Tateomys rhinogradoides, a Sulawesi endemic shrew rat. Shrew rats represent a diverse set of species that have converged on a similar morphology with elongate faces specialized for feeding on forest invertebrates. They are only found in the Philippines, New Guinea, and Sulawesi.

Population genomics of reproductive behaviors

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Reproductive systems span a range of systems in mammals, from social monogamy to extreme cases of polygyny, polyandry, and promiscuity. We are interested in learning whether mating systems can be predicted using patterns of genetic diversity on the sex chromosomes relative to those of the autosomes of mammals. We recently found that the effect of differential variance in reproductive success between the sexes of tonkean macaques was modest. We are currently exploring these same questions in rodents that span a 30-fold range of relative testes mass. Our expectation is that species with large testicles (up to 5% of body mass!) will have the greatest variance in male reproductive success due to the effects of sperm competition. This work is in collaboration with Ben Evans at McMaster University.

Biodiversity inventories

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Our research is heavily dependent on knowledge of where species live and how to tell them apart. In addition, our frequent use of genetic characters requires recently collected museum specimens with appropriately preserved tissue samples. Thus, much of our time is devoted to inventorying small mammals. We've done extensive fieldwork in the Philippines, Indonesia, and the Democratic Republic of the Congo. This fieldwork has supported phylogenetic and phylogeographic investigations of a number of lineages. The ultimate goal of this work is to contribute to an improved understanding of what species are, where they live, and how many of them are out there. Pictured here is Melasmothrix naso, a diurnal shrew-mouse from the highlands of central Sulawesi.