Elsevier Editorial System(tm) for General and Comparative Endocrinology Manuscript Draft Title: Effects of Sex, Age, and Season on Plasma Steroids in Free-ranging Texas Horned Lizards (phrynosoma Cornutum)

The Texas horned lizard (Phrynosoma cornutum) is protected in several states due to its apparently declining numbers; information on its physiology is therefore of interest from both comparative endocrine and applied perspectives. We collected blood samples from free-ranging P. cornutum in Oklahoma from April to September 2005, spanning their complete active period. We determined plasma concentrations of the steroids, progesterone (P), testosterone (T), and corticosterone (CORT) by radioimmunoassay following chromatographic separation and 17β-estradiol (E2) by direct radioimmunoassay. T concentrations in breeding males were significantly higher than in non-breeding males. P showed no significant seasonal variation within either sex. CORT was significantly higher during the egglaying season compared to breeding and non-breeding seasons for adult females and it was marginally higher in breeding than in non-breeding males (P=0.055). CORT concentrations also significantly increased with handling in non-breeding males and egg-laying females. Perhaps most surprisingly, there were no significant sex differences in plasma concentrations of P and E2. Furthermore, with respect to seasonal differences, plasma E2 concentrations were significantly higher in breeding females than in egg-laying or non-breeding females, and they were significantly higher in breeding than in non-breeding males. During the non-breeding season, yearling males exhibited higher E2 concentrations than adult males; no other differences between the steroid concentrations of yearlings and adults were detected. In comparison to other vertebrates, the seasonal steroid profile of P. cornutum exhibited both expected and unexpected patterns, and our results illustrate the value of collecting such baseline data as a springboard for appropriate questions for future research. OSU O K L A H O M A S T A T E U N I V E R S I T Y Department of Zoology 430 Life Sciences West Stillwater, Oklahoma 74078-3052 405-744-5555 Fax: 405-744-7824 30 September 2007 Editorial Office General and Comparative Endocrinology Elsevier 525 B Street Suite 1900 San Diego, CA 92101-4495, USA Dear Ms. Shapiro: We were pleased to learn that our manuscript (Ms. No.: GCE-07-52), “Effects of sex, age, and season on plasma steroids in free-ranging Texas horned lizards (Phrynosoma cornutum)” has been favorably reviewed and is still being considered for publication by General and Comparative Endocrinology. We think that GCE is an excellent venue for this work and have carefully considered the reviewers’ comments in preparing our revision (for detailed responses, see ‘Responses to Reviews’). Our revised manuscript is 30 pages long, including one table and two figures. We hope that you will find it acceptable for publication, but please do not hesitate to contact me if I can provide any additional information. Thank you for the opportunity to have our work published in GCE. Sincerely, Corina L. Wack (Corresponding Author) Stanley F. Fox Department of Biological Sciences Department of Zoology Duquesne University Oklahoma State University Pittsburgh, PA 15282 Stillwater, OK 74078 412-396-4648 405-744-9682 [email protected] [email protected] Eric C. Hellgren Matthew B. Lovern Department of Zoology Department of Zoology Cooperative Wildlife Research Lab Oklahoma State University Southern Illinois University Stillwater, OK 74078 Carbondale, IL 62901 405-744-5551 618-453-6941 [email protected] [email protected] Cover Letter