Parallel Behavioral Divergence with Macrohabitat inAnolis(Squamata: Dactyloidae) Lizards from the Dominican Republic

Abstract

The ecomorph concept of the adaptive radiation of Caribbean anoles is characterized by a suite of behavioral, ecological, and morphological traits that are tightly linked to microhabitat use in lizards. However, most studies on the adaptive radiation of anoles have been conducted in a single macrohabitat type—lowland tropical forests. Because behavior can help organisms cope with different environmental conditions, we can predict that there will be key shifts in behavior within ecomorphs when examined across different macrohabitats, although this idea remains empirically underexplored. Here we utilized the replicated evolution of montane endemics from a primarily lowland species in a clade of trunk–ground Anolis lizards to test the hypothesis that shifts in basking behavior, wariness, and display behavior accompany divergence into montane habitats. The montane specialists A. armouri and A. shrevei each independently evolved from the primarily lowland dwelling A. cybotes in two widely separated mountain chains on the island of Hispaniola. We found evidence for a convergent behavioral response to the high-altitude macrohabitat: A. armouri and A. shrevei spend more time basking, utilize more open environments, and are warier than lowland A. cybotes. We also found divergence in display behavior in A. shrevei. We detected no evidence of divergence in locomotor behavior with elevation among active lizards. Together, our results suggest that the ecomorph concept would be enriched by extending observations of behavior (and other aspects of the phenotype) into different macrohabitats. Future work should focus on whether the observed behavioral shifts are clinal, reflecting local adaptation within A. cybotes, or fixed differences between the lowland generalist and montane species. Adaptation to the macrohabitat has previously been underappreciated as a source of behavioral diversity in Anolis lizards; this study is the first step toward documenting intraecomorph behavioral variation across divergent habitats.