If selective forces on locomotor ability and reproductive biology differ among habitats, we expect to see relationships between habitat, morphology, and life-history traits. Comparative (phylogenetically based) analysis of data from 12 pythonid and 12 boid snake species reveals multiple evolutionary shifts in habitat use, notably in the evolution of arboreal habits. Compared to terrestrial and aquatic taxa of the same overall body size, arboreal species have narrower and more laterally compressed bodies and relatively longer tails. Offspring sizes are not affected by arboreality, but presumably reflecting space constraints within their narrow bodies, arboreal species (1) produce smaller clutch sizes relative to maternal body length and (2) have left and right ovaries that overlap little if at all along the length of the body (i.e., the right ovary is positioned anterior to the left ovary) whereas in terrestrial snakes the two ovaries overlap along much of their length. This modification of ovarian morphology in arboreal snakes presumably reduces the degree of bodily distension during vitellogenesis and pregnancy, thus enhancing climbing ability and camouflage among the branches.

Macroscopic and microscopic examination of the female reproductive tract of Philodryas patagoniensis was conducted in order to observe sperm storage structures and determine morphological changes throughout the reproductive cycle. The oviduct of P. patagoniensis is composed of the infundibulum (anterior and posterior), uterus, utero-vaginal junction, and vagina. The uterine epithelium showed constant secretory activity throughout the reproductive cycle, although increased production of secretory granules was observed in secondary vitellogenic females. Sperm storage occurs in the posterior infundibulum and utero-vaginal junction in pregnant, primary (postpartum), and secondary vitellogenic females. These data suggest that P. patagoniensis may be able to produce several clutches from a single mating. Sperm storage in the posterior infundibulum occurs in sperm receptacles, while in the utero-vaginal junction sperm is stored in crypts. Histochemical tests by periodic acid-Schiff revealed that both sperm storage sites increase the production of neutral carbohydrate-rich granules in the presence of sperm, similar to snakes from temperate regions. This is the first report of sperm storage in the posterior infundibulum of a neotropical snake.

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, pelo apoio a esse trabalho e pelo exemplo de luta, coragem e principalmente por me apresentar ao Prof. Orsi. Ao amigo Otavio pelo carinho e grande incentivo profissional. A amiga Iara Lúcia, obrigada por acreditar em mim. A amiga Graça por todos esses anos de trabalhos, lutas, convívio e amizade! A todos os meus colegas do Butantan, obrigado pelo carinho e ajuda!

This study describes the male reproductive cycle of Sibynomorphus mikanii from southeastern Brazil considering macroscopic and microscopic variables. Spermatogenesis occurs during spring-summer (September-December) and spermiogenesis or maturation occurs in summer (December-February). The length and width of the kidney, the tubular diameter, and the epithelium height of the sexual segment of the kidney (SSK) are larger in summer-autumn (December-May). Histochemical reaction of the SSK [periodic acid-Schiff (PAS) and bromophenol blue (BB)] shows stronger results during summer-autumn, indicating an increase in the secretory activity of the granules. Testicular regression is observed in autumn and early winter (March-June) when a peak in the width of the ductus deferens occurs. The distal ductus deferens as well as the ampulla ductus deferentis exhibit secretory activities with positive reaction for PAS and BB. These results suggest that this secretion may nourish the spermatozoa while they are being stored in the ductus deferens. The increase in the Leydig cell nuclear diameter in association with SSK hypertrophy and the presence of sperm in the female indicate that the mating season occurs in autumn when testes begin to decrease their activity. The peak activity of Leydig cells and SSK exhibits an associated pattern with the mating season. However, spermatogenesis is dissociated of the copulation characterizing a complex reproductive cycle. At the individual level, S. mikanii males present a continuous cyclical reproductive pattern in the testes and kidneys (SSK), whereas at the populational level the reproductive pattern may be classified as seasonal semisynchronous.

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