Size-Assortative Pairing and Social Monogamy in a Neotropical Lizard, Anolis limifrons (Squamata: Polychrotidae)

Abstract

Social monogamy, the formation of stable male-female pairs, is uncommon among reptiles and is particularly rare among squamates, in which only a handful of cases has been reported. Only one case of persistent pair formation has ever been reported in anoles, for Anolis limifrons, at a single site in Costa Rica. Detailed studies of A. limifrons at other sites, however, have not shown evidence of pair formation. I revisited the site where pairing was originally reported to observe pair behavior in this species and to measure morphological traits of paired and unpaired animals. I confirmed that male-female pairs are commonly encountered in the wild, although a smaller proportion of the animals observed in this study were found in pairs than previously reported. I also found evidence for size-assortative pairing; larger males tended to be found with larger females and smaller males were found with smaller females. I did not find any differences in the morphology of paired and unpaired animals. Although social monogamy has not been widely reported in squamates, I suggest that more examples of this phenomenon will be described as the social behaviors of poorly known species are increasingly subject to study.