Assessing how ecology influences transitions to complex socislaity in African cichlid fishes

Abstract

Many human social behaviours, such as monogamy, biparental care, and our extreme ability to learn both independently and from others, are rare across animals. This is unsurprising, as each of these traits should, in theory, be rare. Monogamy greatly reduces male total reproductive output, biparental care should only occur when the potentially massive cost of care is outweighed by the resultant increase in offspring fitness, and non-social species should have little to no need to observe and learn from conspecifics. Despite this, each of these characteristics can be found across vertebrate taxa, and is even overrepresented in some groups. Consequently, these rare and highly derived behaviours have received significant interest and research effort. Research focus has largely centred on mammals, especially primates, and birds. Fishes are greatly overlooked in the literature, despite being the majority of all vertebrate species. This thesis aims to contribute to our understanding of the evolution and cognitive consequences of complex social behaviours, primarily considering African cichlid fishes. Chapter 2 uses phylogenetic comparative methods to investigate the evolutionary drivers of monogamy in marine reef fish and cichlids. The results reveal several potential drivers of monogamy, and clearly show male territoriality, hence, likely male mate guarding, to be a driver of monogamy in cichlids. Biparental care is also shown to be a consequence of the evolution of monogamy in cichlids. Chapter 3 then uses similar techniques to consider the evolutionary causes, consequences, and correlates of biparental care in cichlid fishes. These results show biparental care and type of care provided to be subject to independent evolutionary forces. Chapter 4 addresses the role of sociality and social environment in learning in several cichlid species, with a focus on the cooperatively breeding Neolamprologus pulcher and the non-grouping Telmatochromis temporalis. This chapter finds no clear pattern as to whether more- or less-social cichlids perform better in cognitive tasks than each other, but does show that social environment differently affects each species' performance. Finally, chapter 5 demonstrates social learning in the minimally social Telmatochromis temporalis when presented with a novel foraging task. In summary, cichlid fishes are a useful system to investigate broad questions of the evolution of complex sociality and the potential cognitive consequences.

Date of Award	1 Aug 2020
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Holly Shiels (Supervisor), Susanne Shultz (Supervisor) & John Fitzpatrick (Supervisor)