Maternal care in a glassfrog: care function and commitment to offspring in Ikakogi tayrona

Abstract

Parental care is important for offspring success for many animals. Both male-only and female-only care occur equally often among frogs, creating opportunities to examine ecological factors that may favor sex-specific patterns of care. Experimental tests of care function can elucidate such factors and identify benefits of parental behavior to offspring. In glassfrogs (Centrolenidae), only male egg attendance has been documented and male care is thought to have evolved repeatedly from a state of no-care. We provide experimental evidence demonstrating female care in the glassfrog Ikakogi tayrona—a species sister to all other members of the family. We used repeated observations to quantify egg attendance behaviors, and a removal experiment to evaluate the benefits of maternal care and test whether care function changes with embryonic development. Given the importance of care to female fitness, we examined maternal commitment to providing care in risky situations, using a simple behavioral challenge. We found that egg attendance reduces embryo dehydration and predation. Moreover, the specific benefits of care changed across embryo development, suggesting that different threats to embryos select for egg attendance at different stages. The maternal commitment assay revealed that caring females are more risk-tolerant than non-caring females. Our finding of maternal care in I. tayrona reveals previously unknown diversity in glassfrog parental care and contributes to emerging evidence that care functions are similar among frogs with female-only and male-only egg attendance. This suggests that a lack of sex-specific constraints may have facilitated evolutionary changes in sex roles.