Correlated evolution of parental care with dichromatism, colour, and patterns in anurans

Parental care is widespread among vertebrates, with clear fitness benefits. Caring parents however incur costs that include higher predation risk. Anurans have among the most diverse forms of parental care, and we test whether the occurrence of care is associated with morphology that minimizes predation risk. We first examine whether parental care co-occurs with sexual dichromatism, testing the hypothesis that when one sex is conspicuous, the other is cryptically patterned and cares for the young. From our phylogenetic comparative analyses of 988 anurans distributed globally, we find that parental care is less likely to co-occur with dichromatism, irrespective of the caring sex. We then examine whether colour gradients and patterns that enhance crypticity are associated with the occurrence of parental care. We found that species with male-only care were more likely to have Bars-Bands, but contrary to our expectation, other colours (Green-Brown, Red-Blue-Black, Yellow) and patterns (Plain, Spots, Mottled-Patches) were not associated with caregiving behaviours. The lack of strong correlations between dorsal morphology and parental care suggests that crypticity is not the dominant strategy to minimise predation risk for care-giving anurans, and that the evolution of body colour and parental care are driven by independent selection pressures.