Some like it hotter: differential thermal preferences among lizard color morphs

Abstract

Temperature rules the lives of ectotherms. To perform basic biological functions, ectotherms must make behavioral adjustments to keep their body temperatures near a preferred temperature (Tpref). Many color polymorphic lizards are active thermoregulators and exhibit morph differences in traits related to thermoregulation, such as color, body size, and microhabitat use. The Aegean wall lizard,Podarcis erhardii, is a heliothermic lizard with orange, white, and yellow color morphs that differ in size, behavior, and microhabitat use. Here, we tested whetherP. erhardiicolor morphs from the same population from Naxos island, Greece, differ in Tpref. We hypothesized that orange morphs would prefer lower temperatures than white and yellow morphs because orange morphs are often found on cooler substrates and in microhabitats with more vegetation cover. We obtained Tpref for 95 individuals using laboratory thermal gradient experiments of wild-caught lizards and found that orange morphs do, indeed, prefer significantly cooler temperatures, regardless of body size differences. Average orange morph Tpref was 2.3 ºC lower than average white and yellow morph Tpref. Our results add support to the idea thatP. erhardiicolor morphs have multivariate alternative phenotypes and present the possibility that thermally heterogeneous environments play a role in the maintenance of color polymorphism in this species.

Multivariate models of animal sex: breaking binaries leads to a better understanding of ecology and evolution

“…In lizards, intrasexual color morphs occur in both females and males, and are often associated with alternative sexual phenotypes comprising discontinuous variation in genital morphology (Gilman et al 2019), clutch size (Sinervo et al 2000), mate preference (Pérez i de Lanuza et al 2013), mating strategies (Gross 1982; Sinervo and Lively 1996), and endocrine profiles (Huyghe et al 2009; Brock et al 2020). These distinct sexual phenotypes give rise to ecological specialization among morphs, including thermal preference (Thompson et al 2022), microhabitat selection (BeVier et al 2022), diet (Lattanzio and Miles 2016), and behavior (Brock and Madden 2022; Brock, Chelini, et al 2022). Although each morph utilizes a specialized set of resources, in aggregate this contributes to a greater niche breadth in polymorphic populations, relative to monomorphic populations (Forsman et al 2008); Figure 4).…”