Strategic and tactical fighting decisions in cichlid fishes with divergent social systems

Abstract

The costs and benefits of engaging in a contest will differ depending on the social situation of the individuals involved. Therefore, understanding contest behaviour can help to elucidate the trade-offs of living in differing social systems and shed light on the evolution of social behaviour. In the current study, we compared contest behaviour in two closely related species of Lamprologine cichlid fish. Neolamprologus pulcher and Telmatochromis temporalis are both pair-breeding cichlids, but N. pulcher are highly social, group-living fish, while T. temporalis display no grouping behaviour. To examine how competition varies by species, sex and familiarity, we staged same-sex conspecific contests over a shelter, a resource that is highly valued by both species, where contestants were either familiar or unfamiliar to one another. When we examined tactical and strategic components of these contests, we found that the highly social species had shorter contests and engaged in fewer costly aggressive acts than did the non-social species. Individuals of the highly social species were also more likely to resolve conflicts through the use of submissive displays, while individuals of the non-social species were more likely to flee from conflict. Familiarity increased the use of submissive displays in the highly social species but not in the less social species. Our findings suggest that conflict resolution behaviour and dominance hierarchy formation are fundamentally linked to the evolution of complex social systems.

Group response to social perturbation: impacts of isotocin and the social landscape

“…Between 0900 and 1700 hours, we observed each of these 40 focal subordinate fish for 10 min prior to capture and recorded all social behaviours produced and received. Following published ethograms for this species (Hick et al, 2014;Reddon et al, 2015;Sopinka et al, 2009), we categorized all social behaviours as overt physical attacks (ram, bite, mouth fight), restrained aggressive displays (operculum spreads, fin raises, head shakes), submissive displays (tail quivers, hook displays, submissive postures) or affiliative behaviours (parallel swims, follows, soft touches). We also recorded any aggression produced by the focal fish towards any heterospecific fish.…”

“…They also allow the signaller to remain in the same spatial location rather than fleeing from the dominant (Issa & Edwards, 2006;Ligon, 2014;Matsumura & Hayden, 2006). Consequently, the expression of submissive behaviour is essential for the formation and maintenance of stable groups (Hick, Reddon, O'Connor, & Balshine, 2014;Schenkel, 1967).…”

“…Submissive signals are well developed in N. pulcher (Bender et al, 2006;Bruintjes & Taborsky, 2008;Dey, Reddon, O'Connor, & Balshine, 2013;Reddon, O'Connor, Marsh-Rollo, & Balshine, 2012;Reddon et al, 2015;Reddon et al, 2011;Taborsky, 1985) and appear to facilitate social stability in this species (Hick et al, 2014). To explicitly examine the role of submissive behaviour in modulating the group's response to the focal subordinate, we gave each focal subordinate an injection of isotocin (IT), the teleost fish homologue of oxytocin (Godwin & Thompson, 2012;Thompson & Walton, 2013), or a saline vehicle control, before returning it to the group.…”

The placid slavemaker: avoiding detection and conflict as an alternative, peaceful raiding strategy

“…Conflict escalation within social groups can be avoided through the establishment of dominance hierarchies, the use of ritualized appeasement gestures or displays, or chemical signaling (Preuschoft and van Schaik 2000;van Wilgenburg et al 2005;Ratnieks et al 2006;Hick et al 2014). Encounters between social groups are more difficult to prevent from escalating, but if both sides benefit from it, mediating behavioral mechanisms can evolve (e.g., Neat et al 1998).…”

Cognitive skills and the evolution of social systems

“…As physical contests require a significant investment in time and energy and have a potential cost of physical damage (Huntingford and Turner, 1987), animal social systems have evolved to avoid these, usually signaling with threats or postures that typically emphasize body size and often teeth. Comparing two closely related cichlid fish species from Lake Tanganyika, Hick et al (2014) found that highly social species were more likely to resolve disputes through submissive displays as compared with non-social species, suggesting that the dominance hierarchy formation is likely linked to the evolution of complex social systems.…”