Actinopterygian fishes (subclass Actinopterygii) display considerable diversity regarding forms of parental behaviors and types of carer sex. Contrary to caregiver sex, parental behaviors were not traced at the subclass level. In order to understand the evolutionary history of parental care in the ray-finned fishes, parental care states were mapped upon an existing supertree using parsimony ancestral state reconstruction. We investigated the evolution of substrate guarding, mouthbrooding, external egg carrying and internal gestation. We aimed to test the general hypothesis, according to which, more advanced forms of care were always preceded by simpler ones. We show that, in this subclass, parental care traits evolved from ancestors devoid of parental care. The transition from the ancestral state of no care to substrate guarding was the most frequent, whereas the other transitions recorded low scores. The data supported the evolution of mouthbrooding from substrate guarding, whilst external egg carrying arose from both substrate guarding and the ancestral state, which might suggest independent evolutionary routes of external egg carrying. Consequently, our results did not fully corroborate the general hypothesis mentioned above. Internal gestation evolved both in clades devoid of parental care and in clades descendant from substrate guarders ancestors.

Actinopterygian fishes display considerable diversity of parental behaviors and forms of parenting. In order to understand the evolutionary history in the ray-finned fishes, both characters were mapped, using parsimony ancestral state reconstruction upon an existing supertree. According to the data, in this subclass, parental care and parenting traits evolved from ancestors devoid of parental care or parenting. The transition from the ancestral state to substrate guarding, and that from the ancestral state to uniparental male care were the most observed ones, whereas the remaining transitions recorded low scores. Concerning the evolution of parental care, the data supported the evolution of mouthbrooding from substrate guarding, whilst external egg carrying arose from both substrate guarding and the ancestral state, which suggested the lack of a unique evolutionary pattern. Regarding the evolution of caregiver sex, the data did not support the stepping-stone model since the complete predicted sequence was not observed. In addition, the evolution of carer sex showed higher diversity of transitions among states than recorded in the evolution of parental care, suggesting the absence of a unique evolutionary pattern fitting the entire subclass.