Year-round plasma steroid hormone profiles and the reproductive ecology of gopher tortoises (Gopherus polyphemus) at the southernmost edge of their range

•The first year-round sex hormone profiles for wild gopher tortoises.•Male testosterone is elevated from September to December, and in June.•Female testosterone and estradiol are elevated from August to February.•Female progesterone increases in November and December to a peak in March.•Hormone profiles suggest an extended breeding season in populations below the freeze line. Populations of wide ranging ectotherms often exhibit variation in traits that are influenced by local environmental conditions. Although the gopher tortoise, Gopherus polyphemus, is well studied in pine flatwoods habitats across their range, little attention has been given to coastal populations existing in the southern extreme portion of the range. We examined the reproductive physiology of a coastal dune population in southwest Florida to determine if reproductive cycles vary across populations. Here we present the first year-round sex hormone profiles for a wild population of gopher tortoises. Male testosterone concentrations varied across the year (F11,54 = 2.52, P = 0.015) with elevated values from September to December and minimal levels from April to July, with the exception of a secondary peak during the month of June. Female testosterone and estradiol concentrations varied across the sampling period (T: F11,66 = 8.54, P