Type of Resources

Dissertation/Thesis

Date Created

12-2018

Abstract

The Crotalus intermedius clade is a small group composed of four species: C. intermedius, C. transversus, C. pricei, and the recently identified C. tancitarensis (Alvarado-Díaz and Campbell, 2004; Reyes-Valesco et al. 2013). Though these species are restricted to high elevations of Sky Islands of southern Arizona and throughout México, little has been reported about their natural history and basic biology, including venom composition. Specifically, the Western Twin-spotted Rattlesnake (C. pricei pricei) is a small lizard specialist restricted to the more northern Sky Islands of México, with isolated populations in southern Arizona, where they are a protected species. Crotalus p. pricei is restricted to high elevations, dispersal between mountain tops is impossible, and few studies have investigated venom composition, the predator-prey relationship between C. p, pricei and its primary prey source, Yarrow’s Spiny Lizard (Sceloporus jarrovii), or ecological variables impacting distribution. This project aimed to characterize the venom of species within the Crotalus intermedius clade and the trophic and distributional relationships between S. jarrovii and C. p. pricei by using venom analysis techniques, lethal toxicity assays, and species distribution modeling techniques. Reverse-phase high-performance liquid chromatography (RP-HPLC), gel electrophoresis, and several enzyme assays were used to identify compounds present in crude venom. Lethal toxicity assays were used to determine venom lethality towards Hemidactylus frenatus.(House Gecko) and S. jarrovii. Resource selection probability functions (RSPF) were evaluated to determine spatiotemporal ecological requirements of both C. p. pricei and S. jarrovii. The results of this study provides insight into the venom composition of little known, mountain rattlesnakes, the coevolutionary relationship between a lizard specialist (C. p. pricei) and its natural prey (S. jarrovii), and novel information on the likely distribution of both species based on ecological requirements. This information provides a solid basis for future land management and conservation plans concerning the unique habitats and fauna of the Sky Island ranges.

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