Oviparous species of Sceloporus exhibit either seasonal or continuous spermatogenesis and populations from high-elevation show a seasonal pattern known as spring reproductive activity. We studied the spermatogenic cycle of a high-elevation (2700 m) population of endemic oviparous lizard, Sceloporus aeneus, that resided south of México, D.F. Histological analyses were performed on the testes and reproductive ducts from individual lizards collected monthly. This population of S. aeneus showed a seasonal pattern of spermatogenesis, with 4 successive phases common in other lizards. These include: 1) Quiescence in August, which contained solely spermatogonia and Sertoli cells; 2) Testicular recrudescence (September-January) when testes became active with mitotic spermatogonia, spermatocytes beginning meiosis, and the early stages of spermiogenesis with spermatids; 3) Maximum testicular activity occurred from March to May and is when the largest spermiation events ensued within the germinal epithelia, which were also dominated by spermatids and spermiogenic cells; 4) Testicular regression in June was marked with the number of all germs cells decreasing rapidly and spermatogonia dominated the seminiferous epithelium. February was a transitional month between recrudescence and maximum activity. The highest sperm abundance in the lumina of epididymides was during maximum testicular activity (March-May). Thus, before and after these months fewer spermatozoa were detected within the excurrent ducts as the testis transitions from recrudescence to maximum activity in February and from maximum activity to quiescence in June. Maximum spermatogenic activity corresponds with warmest temperatures at this study site. This pattern known as spring reproductive activity with a fall recrudescence was similar to other oviparous species of genus Sceloporus.

The continued evolution of antibiotic resistance has increased the urgency for new antibiotic development, leading to exploration of non-traditional sources. In particular, snake venom has garnered attention for its potent antibacterial properties. Numerous studies describing snake venom proteomic composition as well as antibiotic efficacy have created an opportunity to synthesize relationships between venom proteomes and their antibacterial properties. Using literature reported values from peer-reviewed studies, our study generated models to predict efficacy given venom protein family composition, snake taxonomic family, bacterial Gram stain, bacterial morphology, and bacterial respiration strategy. We then applied our predictive models to untested snake species with known venom proteomic compositions. Overall, our results provide potential protein families that serve as accurate predictors of efficacy as well as promising organisms in terms of antibacterial properties of venom. The results from this study suggest potential future research trajectories for antibacterial properties in snake venom by offering hypotheses for a variety of taxa.

The urogenital system of male squamates consists of the testis, testicular ducts, and sexual segment of the kidney. These structures undergo seasonal variation, and their morphology is variable across taxa. Despite multiple studies examining the morphology of the various components of the reproductive system, few studies have examined squamates in sympatry. The purpose of this study was to investigate the morphology and seasonal variation of the reproductive system in two taxa that are sympatric with one another, Anolis carolinensis and Sceloporus undulatus, from southeastern Louisiana. Specimens were collected monthly for an entire year and processed for histological and ultrastructural analysis. Both species have a single rete testis leading from the testis to the ductuli efferentes, which leads into the proximal portion of the epididymis. The rete testis consists of a simple squamous epithelium with irregularly shaped nuclei, the ductuli efferentes consists of a ciliated simple cuboidal epithelium, and the epididymis a pseudostratified columnar epithelium. No differences were observed in the morphology of the urogenital systems between taxa but phenological variation was observed in terms of the tissue development for reproduction. Anolis carolinensis has an extended active period and two separated periods of maximal activity evidenced by two peaks in the ductuli efferentes epithelial height and tubular diameter (March and July) whereas Sceloporus undulatus only had a single peak occurring in June. These results suggest that reproductive morphology may be conserved at taxonomic levels above family level, and reproductive activity may be constrained phylogenetically and is not solely dependent on environmental factors, at least in terms of geographic range, though it is acknowledged that microhabitats may play a major role in cyclicity of reproductive events. Future studies examining species at various taxonomic levels, as well as species in sympatry, will provide additional insight into hypotheses concerning abiotic factors and reproductive biology.