Reproductive strategy of male and female eastern spiny lizards Sceloporus spinosus (Squamata: Phrynosomatidae) from a region of the Chihuahuan Desert, Mexico

We examined the reproductive strategy of male (n - 84) and female (n - 62) S. spinosus from a single population in San Luis Potosi, Mexico. The male reproductive cycle peaked in March and April and declined from May to September, and was not correlated with fat body mass, but was positively correlated with liver mass. The female reproductive cycle peaked in April and May and declined from June through November, and was not correlated with fat body mass, but was correlated with liver mass. Mean clutch size based on oviductal eggs was 17.5 +/- 1.9 (n = 12), and was not correlated with female snout-vent length. Our results for S. spinosus are generally similar to those of other populations of the S. spinosus species group. However, there are differences in some traits (e.g., timing of the initiation of the female reproductive cycle; clutch size), suggesting that the S. spinosus group could serve as another model group within Sceloporus to explore ecological and evolutionary causes of among population life history variation.