Does breeding season variation affect evolution of a sexual signaling trait in a tropical lizard clade?

Abstract

AbstractSexually selected traits can be expected to increase in importance when the period of sexual behavior is constrained, such as in seasonally restricted breeders.Anolislizard male dewlaps are classic examples of multifaceted signaling traits, with demonstrated reproductive function reflected in courtship behavior. Fitch and Hillis found a correlation between dewlap size and seasonality in mainlandAnolisusing traditional statistical methods. Here, we present two tests of the Fitch-Hillis Hypothesis using new phylogenetic and morphological data sets for 44 species of MexicanAnolis. A significant relationship between dewlap size and seasonality is evident in phylogenetically uncorrected analyses but erodes once phylogeny is accounted for. This loss of statistical support for a relationship between a key aspect of dewlap morphology and seasonality also occurs within a species complex (A. sericeusgroup) that inhabits seasonal and aseasonal environments. Our results fail to support seasonality as a strong driver of evolution ofAnolisdewlap size. We discuss the implications of our results and the difficulty of disentangling the strength of single mechanisms on trait evolution when multiple selection pressures are likely at play.