Sexual dichromatism in a cryptic poison frog is correlated with female tadpole transport

Abstract

Sexual dichromatism has provided important information for understanding sexual selection, but its link to reproductive success has received little attention. Poison frogs and their relatives within the superfamily Dendrobatoidea present striking color variation. Despite this variability, evidence of sexual dichromatism in the over 330 species described is limited to the gular region of some cryptically colored species. Colostethus imbricolus is a cryptically colored dendrobatid with distinct orange and yellow spots at the axillar, inguinal and femoral regions. Here we show that these spots stand clearly out from the environment during behavioral displays and that they present marked sexual differences in their conspicuousness, with females having more conspicuous spots. Unlike most species of Dendrobatoidea that provide parental care in the form of male tadpole transport, we found that in C. imbricolus, females performed this behavior. By correlating color measurements and behavioral observations, we show that females with a higher number of transported tadpoles are also the most conspicuous. Our findings show a significant association between sexual dichromatism of the spots and female parental care while opening exciting perspectives for the occurrence of both traits. In addition, our results provide significant insights to address the function of dual-color patterns (i.e., cryptic from distance—aposematic from nearby) in amphibians.