Meeting Abstract
The evolution of parent and offspring traits is likely shaped by the social dynamics of family life. Theory has explored how interactions between the sexes impacts variation in parental investment and how such variation favors offspring adaptations. Empirical tests, however, often focus on species with ‘conventional’ sex roles, where mothers provide most of the care. Our research examines how interactions between sexes impact the evolution of paternal and embryo behavior in glassfrogs. We conducted field observations of 40 species from across the family tree. Comparative analyses support that male-only care evolved repeatedly from female-only care, in association with extended care durations and changes in egg-clutch structure. These results suggest that male care and offspring need coevolve. Both care duration and hatching timing vary within and among species. Removal experiments in 6 species found that embryos hatch early to escape abandoned eggs and extend development in ovo under prolonged care. Experiments in 5 species reveal that delayed hatching benefits embryos in multiple ways. Across species, evolutionary changes in the magnitude of hatching plasticity are positively associated with extensions in care duration. These co-extensions occur in species where paternal males continue mating and care for several clutches concurrently. We tested whether social conditions affect paternal and embryo behavior by manipulating male mating-rates within 2 independent origins of male care. Males that mated more cared for eggs longer, and embryos delayed hatching. Thus, hatching plasticity allows embryos to exploit socially-driven changes in parenting. This work supports that embryo strategies are evolving in association with parental care, and provides insight on how family life can alter selection on offspring traits even within the egg.
