The Evolution of Live-Bearing in Lizards and Snakes

摘要: Most reptiles lay eggs, but many lizards and snakes give birth to live young by retaining the eggs within oviducts until birth. The origin of live-bearing in is investigated here posing a theoretical model testing with published data. Predictions are (1) that should evolve cold environments (2) maternal care facilitates evolution live-bearing. Analyses data from over 1,000 species reveal has evolved recently at least 38 times, an additional 60 show intermediate evolutionary stages (egg retention). Tests these support predictions: Species which have or much more likely be found climates than squamates general. presentation this paper differs those most earlier workers distinguishing cases arises i...