Evolutionary transitions in parental care in cichlid fish

Cichlid fishes (Cichlidae) are well suited for testing theories of the evolution of vertebrate parental care. These freshwater teleost fish provide parental care for their offspring, display many different forms of care and have interspecific variation in which sex stays with the young. Here, we assemble the first familywide composite phylogeny based on morphological and molecular studies, and trace two sets of character evolution: form of care (substrate guarding and mouthbrooding), and sex of caregiver (biparental, femaleonly, and maleonly). Mouthbrooding has evolved from ancestral substrate guarding with 10 to 14 transitions and 0 to 3 reversals. The data support hypothesized transitions in the sex of caregiver, with uniparental female care having arisen from biparental care 21 to 30 times with 0 to 10 reversals. There is also evidence that maleonly care evolved once from biparental care. These transitions in parental care characters are the most numerous reported for any family of vertebrates and, to our knowledge, provide the first quantitative support for models of parental care evolution in fish.