title: Using the Specialization Framework to Determine Degree of Dietary Specialization in a Herbivorous Woodrat.
abstract: To be considered a dietary specialist, mammalian herbivores must consume large quantities of a plant species considered "difficult" with respect to nutrient or toxin content, and possess specialized adaptations to deal with plant defensive compounds or low nutritional content. Populations of Neotoma lepida in the Great Basin consume Juniperus osteosperma, a plant heavily defended by terpenes, but a detailed dietary analysis of this population is lacking. Therefore, we investigated the extent of dietary specialization in this species in comparison with the better-studied specialist species, N. stephensi. Microhistological analysis of feces from N. lepida revealed that greater than 90% of their diet in nature was comprised of juniper. In laboratory tolerance trials, N. lepida tolerated a diet of 80% J. osteosperma, similar to that observed for N. stephensi. There was no difference in the abilities of N. lepida and N. stephensi to metabolize hexobarbital, a proxy compound for terpene metabolism. In preference tests of native and non-native juniper species, N. lepida did not exhibit a preference for its native or co-occurring juniper, J. osteosperma, over the non-native species, J. monosperma, whereas N. stephensi preferred its native or co-occurring juniper J. monosperma over non-native J. osteosperma. Behavioral and habitat differences between these woodrat species lead to the categorization of N. stephensi as an obligate juniper specialist with a small range that overlaps that of its preferred food, J. monosperma, and N. lepida as a facultative juniper specialist with a large range, and only a portion of its distribution containing populations that feed extensively on J. osteosperma.
authors.affiliation: Department of Zoology, Weber State University, 1415 Edvalson Dr., Ogden, UT, 84408, USA. micheleskopec@weber.edu.
authors.forename: Michele M
authors.initials: MM
authors.lastname: Skopec
authors.affiliation: Department of Biology, University of Utah, Salt Lake City, 84112, UT, USA.
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Kohl
authors.affiliation: Department of Zoology, Weber State University, 1415 Edvalson Dr., Ogden, UT, 84408, USA.|Department of Biology, University of Utah, Salt Lake City, 84112, UT, USA.
authors.forename: Katharina
authors.initials: K
authors.lastname: Schramm
authors.affiliation: School of Pharmacy, University of Connecticut, Storrs, CT, USA.
authors.forename: James R
authors.initials: JR
authors.lastname: Halpert
authors.affiliation: Department of Biology, University of Utah, Salt Lake City, 84112, UT, USA.
authors.forename: M Denise
authors.initials: MD
authors.lastname: Dearing
mesh_terms: D000818:Animals; D003889:Desert Climate; D004032:Diet; D017753:Ecosystem; D005243:Feces / Q000737:chemistry; D060434:Herbivory; D006591:Hexobarbital / Q000378:metabolism; D018653:Juniperus; D016205:Sigmodontinae / Q000502:physiology*; D013045:Species Specificity; D014589:Utah
chemical_list: D006591:Hexobarbital
keywords: Dietary specialization; Herbivory; Juniper; Neotoma