First Advisor

Luis A. Ruedas

Term of Graduation

Spring 2020

Date of Publication


Document Type


Degree Name

Master of Science (M.S.) in Biology






Nuttall's cottontail -- Geographical distribution, Nuttall's cottontail -- Morphology, Nuttall's cottontail -- Classification, Lagomorpha, Leporidae, Biogeography



Physical Description

1 online resource (vi, 226 pages)


Widespread species often present taxonomic conundrums: are they truly a single panmictic species, or, is the widespread species in fact a polytypic species complex constituted by independently evolving, morphologically or otherwise cryptic species? One such broadly distributed taxon is Sylvilagus nuttallii, with distribution across the western United States, ranging from South Dakota to California, and from Canada to Arizona. The three subspecies constituting S. nuttallii are, however, geographically isolated and it has been hypothesized that they likely constitute independent, species level taxa. However, that study examined only two of the three holotypes, rather than broader geographic and non-geographic variation. In this study I examined the three subspecies under the framework of several distinct species concepts. I used 35 distinct cranial measurements, morphological, and dental, assessments, as well as molecular data in order to assess the taxonomic status of the subspecies in question constituting S. nuttallii. I collected de novo topotypic series, and examined all holotypes, as well as existing specimens in the American Museum of Natural History and Philadelphia Academy of Sciences. In addition, the effectiveness of species conservation efforts is contingent upon the understanding of its biology and evolutionary trajectory. By having a better understanding of the past, present, and hypothesized future of a species, conservation efforts may begin to mitigate the loss of biodiversity by the turn of the next century.


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