Co-evolution of offspring antipredator competence and parental brood defense in convict cichlids

Abstract

Convict cichlids are Neotropical freshwater fish with biparental brood defense of their free-swimming young. In this study, we correlate ontogenetic changes in swimming performance measured by maximum velocity and burst speeds with skeletal ossification of larvae and consider how these data provide insights into the proximate mechanisms for the evolution of parental care. In lab tests, swimming velocity and acceleration of the young increased nonlinearly with body length with a rapid improvement at 7 mm in standard length (SL). The timing of abrupt improvement in swimming velocity and acceleration coincided with the timing of skeletal ossification from cartilage to bone. Radii of defended broods in the field reflected the interaction of parental defense competence and offspring antipredator competence. In the Rio Cabuyo, Costa Rica, brood radii increased steadily until the young were 6.45 mm SL, and then plateaued. Taken together, these data indicate interdependent and co-evolved traits that encompass larval ontogenetic development, antipredator performance, habitat-specific predation regime, and parental care.