Climate change is and will continue to have a negatively impacting biodiversity. In a new paper Wang et al. (2017) note that lizards may experience population declines and extinctions on a similar scale to that experienced by amphibians. Within lizards, viviparous species are hypothesized to be more vulnerable to climate warming, because they have evolved reduced body temperature and heat tolerance, but this idea remains untested. To test this hypothesis, Wang et al. conducted three temperatures (20, 24, and 28 °C) factorial designed experiments on two lizard species Phrynocephalus przewalskii (oviparous) and P. putjatia (viviparous). The experiments simulated warming on oviparous versus viviparous lizards. Their manipulation of ambient temperature affected activity and thermal preference in both species, birth dates in P. putjatia, and egg mass in P. przewalskii. The other examined traits (fecundity, reproductive output, and size, morphology, and sprint speed of offspring) were not affected. Neither lizard species showed different behavioral responses to rising temperatures between the sexes. The viviparous species thermoregulated more actively than did the oviparous species, but the two species did not differ in thermal preference. Warming reduced the activity time allotted for thermoregulation in both species, but the effect was more dramatic in the viviparous species. Their data supports one of the central predictions that lead to the hypothesis that viviparous lizards are more vulnerable to climate warming. Warming constrains activity more dramatically in viviparous species, not because viviparous lizards have evolved reduced body temperature and heat tolerance.
Wang Z, Ma L, Shao M, Ji X. Are viviparous lizards more vulnerable to climate warming because they have evolved reduced body temperature and heat tolerance?. Oecologia. 2017 Oct 10:1-0.