"A thesis submitted to the Graduate Faculty of Georgia Southern University in partial fulfillment of the requirements for the degree Master of Science." Title from PDF of title page (Georgia Southern University, viewed on May 6, 2010). Dana Nayduch, major professor; Lance McBrayer, Oscar Pung, committee members. Electronic version approved: December 2009. Includes bibliographical references (p. 26-30).

Thesis (M.S.) -- Central Connecticut State University, 2006. / Thesis advisor: Tiffany M. Doan. "... in partial fulfillment of the requirements for the degree of Master of Science in Biology." Includes bibliographical references (leaves 44-49). Also available via the World Wide Web.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1955. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 121-123).

Area used by male and female Phrynosoma mcallii (Hallowell) was studied in a population locted on the Barry M. Goldwater Aerial Gunnery Range near Yuma, Arizona. Area used by males and females shifted through time and did not fit the definition of home range. Summer male and female area used was not significantly different (F=2.625, df=1, P=0.131), but male areas used were significantly larger for 15-day time periods (F=9.67, P=0.0003). Males overlapped the area they occupied in consecutive 15-day time periods more often than did females. Female area used never overlapped within a 15-day time period. Male area used overlapped those of other males and females within a 15-day time period.

We studied the Flat-tailed Horned Lizard, Phrynosoma mcallii, and the Sonoran Horned Lizard, P. goodei, in an area of narrow sympatry near Yuma, Arizona, and found they overlapped broadly in use of available food resources, body size, and growth rates. We compared diet (Chapter 2), growth and reproduction (Chapter 3), and survivorship (Chapter 4) of P. mcallii and P. goodei during two years of drought followed by a year of higher-than-average rainfall. We predicted that P. mcallii would be more tolerant of drought conditions than its congener, since P. mcalliiis found only in an extremely arid region while P. goodei is part of a more northerly-clade and that P. goodei is excluded from the sandy habitat of P. mcallii due largely to the paucity of rainfall and the lack of moisture-holding ability of the sand. During the extended period of drought food became limited, horned lizards lost mass, and there was less growth and reproduction. While both species showed strong differences between dry and wet years, the within-year differences between species were generally small. When resources were abundant we witnessed rapid growth for both P. mcallii and P. goodei and a much higher rate of reproduction. While both species showed similar growth patterns, P. mcallii had a smaller adult body size, larger hatchling size, and seasonally-delayed reproduction compared to P. goodei; differences we propose are adaptations for frequent periods of drought, but which may be disadvantageous in years of abundant resources. We used mark-recapture analysis to derive estimates of detection probability and survival rates. Contrary to prediction, survival rate estimates were higher for P. goodei than for P. mcallii, and higher in dry years than in wet years. However, decreased probability of detection and increased emigration in the wet year confounded survival rate estimates. We also reviewed the conservation and management of P. mcallii, a species of conservation concern (Chapter 5). We proposed using fine-scale scat surveys rather than mark-recapture surveys for the long-term monitoring of P. mcallii.