Maintenance of Spatial Distribution by Convict Cichlid Pairs Is Influenced by Parental Defense Behavior toward Conspecific and Heterospecific Parental Pairs

Parental defense of offspring may be risky, so parents should balance costs and benefits, making context-dependent decisions based on the threat to offspring. Our previous field studies on Convict Cichlids, Amatitlania nigrofasciata, showed that the risk of brood mixing impacts aggression toward conspecific intruders. We also previously observed that parental pairs distribute differently in relation to conspecifics versus heterospecific pair locations with brood defense appearing to vary depending on intruder species (i.e., there appeared to be more aggression toward conspecifics than heterospecifics at closer distances). In the current study, we mapped pair distribution and found that more Convict Cichlid pairs had at least one neighboring pair within 3 m than did not. In addition, pairs with neighbors tended to be closer to heterospecific pairs than to conspecific pairs. To explore the relationship between the spatial distribution of pairs and parental defense behavior, we presented pairs of parental Convict Cichlids with stimuli consisting of a conspecific parental pair or a heterospecific parental pair (Hypsophrys nematopus). Each focal pair was exposed to each species separately and then simultaneously at both near (20 cm) and far (60 cm) distances. During separate presentations, focal parents were more aggressive at near distances versus far distances for both conspecifics and heterospecifics, though the aggression toward heterospecifics was always less than that toward conspecifics at each distance. In the simultaneous presentations, the focal parents were always more aggressive toward conspecific stimuli. These results support the idea that each species represent separate risks (such as conspecific brood mixing or predation) and benefits (such as shared offspring or territory defense) to reproductive fitness, which help shape the observed natural distribution of pairs.