Reproduction of the yellow-backed spiny lizard, Sceloporus uniformis (Squamata: Phrynosomatidae) from California

The reproductive cycle of Sceloporus uniformis was studied by a histological examination of gonads from specimens collected from five California counties: Inyo, Kern, Los Angeles, Riverside and San Bernardino. Males followed a testicular cycle in which sperm production (spermiogenesis) started in March and was completed in August. The smallest reproductively active male measured 79 mm SVL. Females were reproductively active from March into July. Mean clutch size for 20 females = 6.75 ± 2.0 Sd, range = 3-10. The smallest reproductively active female (enlarged follicles \u3e 5 mm) measured 78 mm SVL. Histological evidence is presented (oviductal eggs and concomitant yolk deposition) that multiple clutches are produced by some females of S. uniformis