Record Details

Abts, Marvin L
Reproduction in the saxicolous desert lizard, Sauromalus obesus: the male reproductive cycle
Journal Article
Dipsosaurus dorsalis;Sauromalus obesus
Aspects of reproduction were examined for male chuckwallas, Sauromalus obesus as part of a 7-yr life history study. Size and age at reproductive maturity were 125 mm snout-vent length and 2 yr, respectively. All males exceeding minimum size and age produced mature spermatozoa in most years. Confirmation of spermatogenic activity was more reliable than testis volume or mass in estimates of breeding condition because testis size was highly correlated with body size at the time of breeding. The secretory cycle of interstitial cells was synchronized with development of reproductive organs and secondary sexual characteristics. Epididymal and vas deferens epithelia appeared capable of resorption and secretion. Secretions of the sexual segment of the kidney may contribute to formation of seminal fluid. Corpora adiposa were probably largely devoted to reproduction. Spermatogenesis appeared not to be energy limited because of the early age at reproductive maturity and because all adult males in the population typically produced spermatozoa. Seasonal changes in seminiferous and testicular accessory tissues were highly synchronized, and spermiation always occurred in May and June. The timing of spermiation was similar for male chuckwallas over much of the species' geographic range.