Population-specific co-evolution of offspring anti-predator competence and parental brood defence in Nicaraguan convict cichlids

Parental care in fishes is a three-way interaction among brood predators, parental brood defence, and the escaping ability of the developing young. Convict cichlids are Neotropical freshwater fish with prolonged biparental brood defence of their eggs and free-swimming larvae. In a previous study, developmental timing of changes in larval swimming performance was correlated with larval skeletal ossification and biparental brood defence in convict cichlids in the Río Cabuyo, a stream in Costa Rica (Wisenden et al. 2015 ). Here, we repeat this study on a population of convict cichlids from Laguna de Xiloá, a volcanic crater lake in Nicaragua. We found that fish from Laguna de Xiloá also showed correlations among swimming performance and skeletal ossification of the larvae, and brood defence by the parents. However, in Laguna de Xiloá the developmental timing of these events was delayed relative to the Río Cabuyo population. The population difference between Costa Rica and Nicaragua could be an effect of genetic divergence or an artefact of phenotypic plasticity between lab-reared fish (Costa Rica) versus wild-caught fish (Nicaragua) for ossification scores. To resolve this question we repeated study using lab-reared fish of brood stock from Laguna de Xiloá. Comparing among the lab-reared Costa Rican fish, and lab-reared and field-collected Nicaraguan fish, we found that the timing of ossification was significantly delayed for both Nicaraguan samples relative to the Costa Rican samples. These shifts likely reflect population differences in selection on anti-predator competence of the young and, consequently, parental brood defence. These data indicate that larval ontogenetic development, anti-predator performance and parental care co-evolve with site-specific ecological differences.