Dewlap size in male water anoles associates with consistent inter-individual variation in boldness

Male sexually selected signals can indicate competitive ability by honestly signaling fitnessrelevant traits such as condition or performance. However, behavior can also influence contest outcomes;in particular, boldness often predicts dominance rank and mating success. Here, we sought to determi ne whether male ornament size is associated with consiste nt in dividual differences in boldness in water anoles Anol is aquaticus. We measured the relative size of the dewlap, a flap of skin under the chin that is a sexually selected ornament in Anolis lizards, and tested for associations with responses to a novel and potentially risky environment: time to emerge from a refuge into an arena and number of head sea ns post-emergence. We found that in dividuals con siste ntly differed in both time to emerge and head sea nning (i.e., in dividual resp on ses were repeatable), and that dewlap size was negatively related to nu mber of head sea ns. This suggests that orname nt size could indicate male boldness if seanning represents antipredator vigilance. We found that males that had larger relative dewlaps were also in better body condition, but boldness (i.e., head scann ing) was not related to condition. Lastly, we found con siste nt d iff ere nces in behavior betwee n trials, showing that anoles were becoming habituated or sensitized to the testing arena. Overall, our study shows that in additi on to indicating con dition and perform a nee, dewlap size could also honestly indicate male boldness in Anolis lizards.

Trait allometries generate super-honesty in Anolis dewlaps and may underlie sexual dimorphism

Whether or not sexually selected traits consistently exhibit positive allometry(i.e.are disproportionately large in larger individuals)is an ongoing debate.Multiple models and exceptions to this rule suggest that the underlying drivers of sexual trait allometry are nuanced.Here,we compare allometries of sexual and non-sexual traits of a species(Anolis aquaticus)within a well-studied lizard genus to test the competing hypotheses that sexual traits are,or are not,defined by positive allometry.We further consider the relationships of trait functions,which are relatively well understood in the genus Anolis,and allometry to identify potential drivers of allometric patterns.In particular,we explore how trait allometries interact to influence total organism function and generate sexual dimorphism.We quantified size(of targeted traits)and color of a sexual signal(the dewlap)in Anolis aquaticus in the field.The dewlap conveyed information relevant to intra-sexual combat and exhibited positive allometry.Overall,our results suggest that using single-trait allometries as indicators of past selection provides only an incomplete understanding of trait evolution.Although the function of positive allometry in some individual sexual signals(e.g.those conveying“super-honest”information)may be straightforward,we illustrate how scaling relationships interact synergistically to influence the function of phenotypes and propose avenues for future research.

Sexual signal conspicuity is correlated with tail autotomy in an anoline lizard

Sexual selection favors conspicuous signals that animals can use to communicate with conspecifics and/or to attract mates.However,natural and sexual selection are often in opposition,as conspicuous sexual signals can also be detected by eavesdropping predators,forcing these signals to also evolve in light of natural selection(Andersson 1994).