Biology subjects

Riley, R. J.

Publications and source records attributed to Riley, R. J..

3 recordsLinked to original sources

bioRxiv2018

The development of social interactions in Corydoras aeneus larvae

Very young animals develop life skills as they mature, and for social animals this includes the acquisition of social abilities such as communication. Many animals exhibit changeable patterns of social behavior based on development, and social experience during the juvenile period can be vital for the development of necessary social behaviors in adulthood. We investigated the development of a distinctive tactile interaction behavior in Corydoras aeneus, the Bronze Cory catfish. Adults use this behavior to coordinate group activities during foraging and flight responses from predators, and the development of this behavior in larvae is of interest in investigating how communication and social behaviors develop as an individual matures, and which factors affect their development. We found that larvae respond to applied tactile stimulation with a flight response far less often as larvae matured, implying that larvae become less sensitive to tactile stimulation with age. Given that adults frequently interact with one another tactilely, this development is consistent with developing appropriate social behavior in adulthood. We also found that social exposure affects the development of the larval response to tactile interactions with conspecifics, and that isolation in the earliest larval stage leads to a greater likelihood of responding to a tactile interaction with a conspecific with a flight response. This suggests that social exposure is important for developing an appropriate response to tactile stimulation in social settings and underscores the particular importance of early life experiences in the development of sociality.

animal behavior and cognition↗

bioRxiv2018

The role of tactile interactions in flight responses in the Bronze Cory catfish (Corydoras aeneus)

One of the primary functions of animal aggregations is defense against predators. Many social animals enjoy reduced predation risk as a result of grouping, and individuals within groups can benefit from information transferred by their group-mates about a potential predator. We present evidence that a tactile interaction behavior we term nudging substantially modified group responses to a potential threat in a highly social catfish species, Corydoras aeneus. These catfish deployed nudges during flight responses, and these nudges were associated with a greater likelihood of group cohesion following a threat event. Increased nudging behavior resulted in longer flight responses. In addition, individuals that perceived the threat first were more likely to initiate nudges, implying that nudges could be used to alert group-mates to the presence of a threat. Taken together, our results suggest that tactile communication plays an important role in gaining anti-predator benefits from sociality in these fish.

animal behavior and cognition↗

bioRxiv2018

Coping with strangers: how familiarity and active interactions shape group coordination in Corydoras aeneus

Social groups whose members have had sustained prior experience with each other frequently exhibit improved coordination and outperform groups whose members are unfamiliar with one another. The mechanisms by which familiarity assists coordination are not well known. Prior social experience may simply allow individuals to learn the behavioral tendencies of familiar group-mates and coordinate accordingly. In the absence of prior social experience, it would be adaptive for individuals to develop strategies for coping with unfamiliar others to minimize the disadvantage of unfamiliarity. To explore the dynamics of familiarity in shaping group behaviors, we used a highly social catfish, Corydoras aeneus, that utilizes a distinctive, observable tactile interactions. Here we describe this tactile interaction behavior, physical \"nudges\" that are deployed to initiate group movements and maintain contact with group-mates during group movements. We then report the results of two experiments exploring the relationship between nudges and coordination. First, within triplets of two familiar and one unfamiliar individual, we found no individual differences in nudging rate based on familiarity. Despite all individuals interacting at similar rates, however, unfamiliar individuals failed to coordinate as well as their familiar group-mates, and were more frequently absent from group movements. Second, comparing pairs of familiar with pairs of unfamiliar fish, there was no difference in the level of coordination between pairs. Instead, we found that unfamiliar pairs exhibited significantly higher nudging rates, suggesting that unfamiliar pairs could compensate for their unfamiliarity by nudging more frequently. In contrast, familiar individuals coordinated with comparatively little nudging, presumably because they were experienced with each other. Overall, these results suggest that nudges can be used to improve coordination of group activities, but that their usage is reduced in the case of familiar individuals, implying that these potential signals may be costly.

animal behavior and cognition↗