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.