Date of Award:


Document Type:


Degree Name:

Master of Science (MS)



Committee Chair(s)

Joseph R. Mendelson III


Joseph R. Mendelson III


This study revealed that P. decurtatus primarily eat squamate eggs, and that the diet of P. browni appears to consist entirely of squamate eggs; gecko tails constitute a very small proportion of the diet of P. decurtatus. Feeding in both species occurred throughout their active seasons and both species increased prey consumption in August. The sexes of P. browni, but not P. decurtatus showed different monthly feeding patterns. Desert-of-collection did not affect P. decurtatus monthly feeding patterns. Phyllorhynchus decurtatus collected from the Sonoran Desert and P. browni, which is found only in the Sonoran Desert, showed similar monthly patterns of prey consumption. The mean number of eggshells consumed per individual P. browni increased significantly in August, but this was not the case for P. decurtatus. Both species seemed to slash the eggs at one end, probably with their enlarged maxillary teeth, and swallowed this end first.

The previously recognized subspecies artificially compartmentalize the inconsistent variation in this species. There was extensive overlap in all morphological characters examined between four subspecies and intergrades of P. decurtatus. ANOVA revealed that there were significant differences between mean scale and blotch counts between putative subspecies, but they did not represent discrete differences among the subspecies. Discriminant functions analysis revealed that individuals could often be classified correctly, but that misclassified animals were not classified by the analysis in a geographically consistent manner. Principal components analysis revealed that phenotypes did not group together in a geographically consistent manner. Regression analysis revealed a longitudinal cline in ventral scale number, as well as some weaker clinal trends in other characters.



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