Evolution of Viviparity and Placentation

Viviparity (live-birth) has evolved independently an extraordinary number of times (>150) among vertebrates. The origin of viviparity imposes several physiological challenges that need to be overcome (elimination of metabolic waste, exchange of respiratory gases, and transport of water and nutrients). Moreover, viviparity dramatically changes the way an organism interacts with its environment.
I have studied the evolution of viviparity in squamates (snakes and lizards), the group that, by far, exhibits most (~75%) origins of viviparity. Specifically, I focus on morphological, ecological, and phylogenetic aspects of the transition to viviparity. I aim to understand how and why multiple species have achieved this evolutionary transition.
A developing snake embryo.
Related publications

Reproductive Biology

Brazil has more than 730 species of squamates (lizards, snakes, and amphisbaenians), but the reproductive cycles of most of these species remain poorly known. One of my research interests is to describe various aspects of squamate reproductive output (clutch size, reproductive frequency) and reproductive cycles (gametogenesis, mating, sperm storage, ovulation, and egg-laying/parturition). Moreover, I also want to understand how reproductive traits are influenced by biotic and abiotic factors and how they are constrained by phylogeny.
A false-coral snake (Oxyrhopus guibei) laying eggs. Photo: Fausto Barbo.
Related publications ​(* = mentored student)

Natural History

As with reproductive biology, many other aspects of the natural history of Brazilian snakes and lizards are still poorly understood. ​Thus, I have always been interested in investigating various aspects of the natural history of squamates, including feeding ecology, feeding behavior, activity patterns, and geographic distribution. 
Enyalius iheringii. Photo: Serena Migliore
Related publications (* = mentored student)
© 2018 by Henrique Braz
Last updated May 2020