Diversity of Reproductive Strategies Among Brazilian Lizards and Snakes: The Significance of Lineage and Adaptation

Abstract

At one time, it was believed that the local environment was the most important determinant of reproductive strategies in squamate reptiles (Tinkle et al. 1970). Long-term field studies demonstrating geographic differences in reproductive characteristics among populations of individual species occurring in different habitats (e.g., Tinkle and Ballinger 1972; Ballinger 1979) !ended support to this notion. If the local environment were the overriding variable contributing to life history variation, it would be expected that species at any given locality would be more similar to each other in reproductive characteristics than to species or populations occurring in very different habitats. More recently, it has been demonstrated that lineage (phylogeny), foraging mode, body size, and body shape. as dictated by habitat selection, account for more of the variation in life history characteristics among squamate reptiles than the local environment (Vitt and Congdon 1978; Vitt 1981; Vitt and Price 1982; Dunham and Miles 1985; Dunham et al. 1988), even though the latter certainly influences reproductive characteristics (see below). In order to understand the evolution of reptilian life histories, it will be necessary to consider all components of variation (Ballinger 1983). The greatest gap in our knowledge of reptilian reproductive palterns stems from a lack of data on tropical species, which comprise a vast majority of the species on earth. The taxonomically diverse reptilian fauna of Brazil is extremely complex in terms of biogeography, ecology, and life history patterns. In this report, I examine reproductive patterns among Brazilian lizards and snakes based primarily on my own research in the three predominant morphoclimatic domains (see Ab'Saber 1967, 1977); caatinga, cerrado, and the Amazonian portion of hylaea. Descriptions of important features of the squamate faunas of these domains and their biogeography have been recently presented (Vanzolini 1976, 1981, 1988; Rodrigues 1988). The squamate faunas of Brazil are ideal for examining reproductive strategies of tropical reptiles because of their taxonomic and ecological diversity, and because peculiarities of species with limited geographic distribution can be compared with geographic variation of species with extensive geographic distrib-utions. What I present will be based partially on published data and partially on my own unpublished studies. Data will appear in the form of summaries directed toward three general topics: ( l) diversity of reproductive strategies among squamate reptiles at single localities; (2) patterns within species and among closely related species occurring in drastically different habitats; and (3) local adaptation and habitat selection. My treatment of these topics is by no means exhaustive; rather, [ have selected examples to illustrate these points.