Abstract
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.