JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. Society for the Study of Amphibians and Reptiles is collaborating with JSTOR to digitize, preserve and extend access to Journal of Herpetology.ABSTRACT-Sceloporus grammicus microlepidotus is a viviparous, high altitude Mexican lizard. Specimens were obtained from several locations in the Parque Nacional de Zoquiapan, Mexico, Mexico. This species exhibits a reproductive cycle in which ovulation and fertilization occur during the fall and parturition the following spring. Vitellogenesis begins in late July in female S. g. microlepidotus, whereas the onset of testicular development occurs in February. Thus, it appears that male reproductive activity is initiated in spring, whereas female reproductive activity is initiated in the fall. The adaptive significance of fall courtship and mating in lizards is discussed. Woodbury, M. and A. M. Woodbury. 1945. Life history of the sagebrush lizard Sceloporus g. graciosus with special reference to cycles in reproduction. Herpetologica 2:175-196.

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Optimal offspring size theory states that natural selection should balance reproductive output by optimizing between offspring size and offspring number. If a species has evolved an optimal offspring size, the fitness of larger females should be increased by simply producing more offspring of an optimum size. In contrast, when offspring size is not optimized, the morphological constraint hypothesis may apply, and in this case, maternal fitness is increased by producing the greatest number of the largest offspring that mothers are physically capable of producing. We used a log-log allometric regression approach on clutch size, egg size, and body size data to test the application of optimal offspring size theory and the morphological constraint hypothesis in the Mexican mud turtle (Kinosternon integrum) in southern Mexico. Our results indicate that this turtle seems to follow the morphological constraint hypothesis when all data are analyzed together, but when data are divided between small (< 140 mm plastron length) and large females (> 140 mm plastron length), optimal offspring (egg) size theory was supported only in large females, while the morphological constraint hypothesis was supported in small females. Our results thus indicate that K. integrum females may increase their fitness in two different, size-dependent ways as they grow from size at sexual maturity to maximum body size.

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