Lizards that display sociality are viviparous species; in contrast, oviparous lizards do not appear ...

Viviparity could facilitate the evolution of social behavior in two ways. First, viviparous lizards give birth in the mother's retreat sitethat is, in the shelter where the mother livesand this is likely to be a safe place for the newborn lizards to remain. In contrast, the nests of oviparous lizards are not usually in the mother's retreat site and may not even be within her home range. As soon as the newly hatched lizards emerge from the nest, they must seek shelter and they are likely to scatter as they do that. Second, the mother and babies are in the same place when viviparous species give birth, and the mother may be able to defend her babies against some predators, making it beneficial for the newborn lizards to remain with the mother. In contrast, oviparous lizards do not guard their nests, so the mother is not present when her babies hatch.