Date of Award


Degree Name

Master of Science


Biological Sciences


Jerry D. Johnson


The objective of this study was to compare the ectoparasitic loads between two syntopic whiptail lizard species (Teiidae) that differ in their reproductive modes; Aspidoscelis marmorata (bisexual) and A. tesselata (unisexual). The study site was located on Indio Mountains Research Station (IMRS) in a Chihuahuan Desert Scrub landscape in Hudspeth County, Texas. Previous studies conducted at IMRS showed the two species having similar diets, morphology, and reproductive characteristics, but fluctuated in nematode loads. No comparative study of ecotoparasitic mites (Eutrombicula alfreddugesi) between the two species has ever been done.

Aspidoscelis marmorata (n = 141) and A. tesselata (n = 144) were captured during the time period of August 2010 through October 2012 in over 100 pitfall traps arranged in transects and later marked by toe clipping. The total numbers of mites (4036 mites, A. marmorata; 3787 mites, A. tesselata) were counted on the entire body of each lizard using a dissecting microscope. During the first year cycle, Aspidoscelis marmorata (n = 33, µ = 101.8 mites) were about half (0.531) less likely for having mites as compared to A. tesselata (n = 46, µ = 53.9 mites) for the first year infection cycle (p = 0.044), but on average had significantly higher infection rates (p > 0.0001). In the second year, a role reversal occurred, with A. tesselata (n = 24, µ = 43.6 mites) having a significantly higher infection rate compared to A. marmorata (n = 32, µ = 21.7 mites), but with no differences in prevalence (p = 0.181). Analysis of body location of infection show A. marmorata (n = 97) having lower sacral loads compared to A. tesselata (n = 85), (p < 0.001), but with higher infection rates on the abdominal scales (p < 0.001). This research shows evidence both accepting and rejecting the Red Queen Hypothesis within a single lizard community on IMRS, with variability between the two sampling years.




Received from ProQuest

File Size

77 pages

File Format


Rights Holder

William Dawson Lukefahr