School of Life Sciences
University of Nevada, Las Vegas
4505 Maryland Parkway
Box 454004
Las Vegas, NV 89154-4004
(702) 895-2478
mantooth (at) unlv.nevada.edu
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My research interests are focused on the historical biogeography and systematics of various mammalian taxa, particularly those restricted to desert regions of the world. The biogeographic questions I ask deal with a level and interpretation of biogeographic scale and the resulting patterns. In other words, I examine taxa at different taxonomic levels (e.g. species, genera, families) that are distributed on various different scales. For example, most species are geographically restricted to particular local regions (e.g. North American aridlands). Thus, we can examine the embedded phylogeographic structure of a single species (within and between populations) on a regional scale. A single species can also be distributed across various different geographic and climatic zones, encompassing a much broader scale.
A single genus, which can include multiple species, can exhibit a distribution that covers a much broader geographical area, such as an entire continent or biogeographic zone, or even several biogeographic zones. By examining the phylogenetic structure of these taxa, we are expanding the biogeographic scale. When we examine the biogeographic properties of various species within a widely distributed genus, we can examine multiple scales of historical biogeography, from the locally distributed populations to the more widely distributed higher taxon.
In order to address these questions, I examine the molecular evolution and phylogenetics of mammalian taxa using various molecular techinques, including DNA sequecing of specific molecular markers. I can then use the sequence data to reconstruct the evolutionary histories of the taxa I am examining. These evolutionary histories can be correlated with past geologic and climatic events to explain the phenomena that have led to the current distributions of particular taxa. These patterns are often evidence of past events stemming from either vicariant or dispersal events in the evolutionary history of the organisms.
| INTERESTING LINKS |
| Mammalogy @ UNLV |
| American Society of Mammalogists |
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I am examining the molecular variation at both the population and specific levels within the antelope squirrels (Ammospermophilus). This genus ranges throughout and is restricted to the aridlands of western North America. The most widespread species, the white-tailed antelope squirrel (A. leucurus), occurs from southeastern Oregon to the southern tip of Baja California. Four other species are found in the various regional deserts of North America: A. harrisii occurs in the Sonoran Desert, A. insularis is an isular form found off the coast of Baja California in the Sea of Cortez, A. interpres is found in the Chihuahuan Desert, and A. nelsoni is restricted to the San Joaquin Valley in south-central California. It is hypothesized that this genus originated at approximately the same evolutionary time as the earliest desert-adapted flora, suggesting that this taxon and the deserts of North America may share a common evolutionary history. The phylogeographic patterns found within this genus, particularly within A. leucurus, are concordant with patterns seen in other taxa with similar distributions (e.g. Dipodomys, Chaetodipus).Similar phylogeographic patterns observed in co-distributed taxa may indicate that these groups shared a common evolutionary history and were exposed to the same or similar geologic or climatic events that have led to their current systematic affinites and geographic distributions.
I am also examining the phylogeographic substructure within Pipistrellus hesperus, the western Pipistrelle, which is restricted to the aridlands of western North America (see map). This species exhibits a geographic distribution similar to other species that have evolved with and within the deserts of this region (e.g. Ammospermophilus, above). By examining the phylogeography throughout the range of this species, we can assess and compare similar phylogenetic patterns between codistributed taxa. By examining similar biogeographic and geologic patterns, we can begin to formulate convincing hypotheses to explain the biogeographic histories and the evolution of the habitats and the species that are distributed within those habitats. This comparative phylogeographic approach allows much more robust conclusions about the species we study and their evolutionary histories.
