Meeting Abstract

116.3  Saturday, Jan. 7  Temperature-Dependent Sprint Performance of Nocturnal and Diurnal Geckos: Does Dollo’s Law Apply to Physiological Traits? LUKEN, Alissa N.*; ESPINOZA, Robert E.; California State University, Northridge

One of the most intriguing and rare phenomena in evolutionary biology is the occurrence of evolutionary reversals because of the presumed difficulty of re-evolving “lost” traits (AKA: Dollo’s law). Most of the world’s 1200+ gecko species are nocturnal and active at body temperatures that are suboptimal for performance. Yet, geckos descended from ancestrally diurnal lizards, which are generally active at temperatures near their thermal optimum. Several gecko lineages have independently reversed to diurnality, possibly to take advantage of activity temperatures closer to their optimum for performance. We tested whether these reversals to diurnality are associated with a return to performance levels of typical diurnal lizards or whether their long history of nocturnality has compromised gecko performance. We hypothesized that diurnality in geckos would be associated with higher sprint performance at warmer temperatures (as for typical diurnal lizards) and a decrease in performance at lower temperatures compared to closely related nocturnal geckos. Following Dollo’s law, we predicted that the maximum performance of diurnal geckos would not approach values of typical diurnal lizards. We used a comprehensive phylogeny of geckos to identify the nocturnal sister taxa of secondarily diurnal geckos. 17 gecko species were sprinted at five ecologically relevant temperatures and maximum sprint performance was determined for each temperature. Sprints analyzed to date (three nocturnal:diurnal species pairs), show no difference in temperature-dependent sprint performance between the nocturnal and diurnal species. This may indicate that thermal physiology is evolutionarily conserved in geckos; however, data from additional species are needed to determine whether this pattern is widespread.