How do viviparous and oviparous lizards reproduce in Patagonia? A comparative study of three species of Liolaemus

In the cold temperate climate of Patagonia, reproduction and growth of ectotherms are restricted to brief seasons, particularly at high latitudes. This energy constraint has affected the evolution of life history traits such as sexual maturity, clutch size, offspring size, reproductive effort, and fecundity. Limitations on the timing of reproductive events and the allocation of energy to offspring have a vital role in the fitness of the species, and it is expected that oviparous and viviparous lizards respond with inter- and intra-specific differences to different environmental conditions partly because of thermal constraints on the development of nestlings. We studied the reproductive cycles of two populations in Patagonia, Argentina (43° and 46°S), of each of three species: the southernmost oviparous liolaemids, Liolaemus bibronii, and Liolaemus boulengeri, and the viviparous Liolaemus lineomaculatus. The three species showed annual and synchronous reproductive cycles between males and females with birth or hatching occurring at the end of summer, showing common evolutionary paths in their reproductive biology. In addition, the oviparous species seem to have adapted to cold and arid environments at high latitudes, in contrast to a major prediction of the cold climate hypothesis for the evolution of viviparity.