Taylor, Benjamin Aaron; (2021) The evolution and mechanisms of caste plasticity in vespid wasps. Doctoral thesis (Ph.D), UCL (University College London).

Preview	Text THESIS.pdf - Accepted Version Download (5MB) | Preview
	Archive BAT_thesis_supplementary_tables.zip - Supplemental Material Download (923kB)

Abstract

Social insects are ecologically dominant predators, pollinators, herbivores and detritivores across many terrestrial ecosystems. Key to the ecological success of these species is a uniquely strong division of labour between reproductives (‘queens’) and non-reproductives (‘workers’). In some social insect species, reproductive division of labour is obligate and developmentally determined, but many other taxa possess full reproductive plasticity, which is the basal state for social insect evolution. Answering the question of how division of reproductive labour is maintained in the presence of reproductive plasticity is an important prerequisite to understanding how and why this plasticity has been lost in the most derived social insect taxa. In this thesis, I address this question using two species of social wasp which exhibit strong division of reproductive labour but full reproductive plasticity. Two chapters of the thesis examine responses to queen loss in the European paper wasp P. dominula, in order to understand the mechanisms by which groups accommodate the loss of a reproductive. In Chapter 2 I show that in this species, groups generate replacement reproductives rapidly and with little conflict by relying on an age-based succession criterion. In Chapter 3 I analyse the transcriptomic mechanisms that underlie this succession process, and show that variation in individuals’ phenotypes only partially explains their transcriptomic responses, a result that suggests hidden costs of queen loss. In Chapter 4, I analyse individual-level transcriptomic data from a facultatively social tropical hover wasp, Liostenogaster flavolineata, which forms linearly age-based dominance hierarchies in which individuals exhibit progressively reduced foraging effort as they move up in rank. I show that despite differences in social structure, variation in gene expression in colonies of this species is surprisingly similar to that of obligately social species such as P. dominula. I also find that genes that are associated with indirect fitness in L. flavolineata are more strongly evolutionarily conserved than genes associated with direct fitness, a surprising result that runs counter to results obtained for other social insect species. Additionally, in Chapter 5 I argue for a reconceptualization of the loss of reproductive plasticity that has occurred in more complex insect societies. Taken as a whole, this thesis sheds light on the behavioural and transcriptomic mechanisms by which distinct fitness strategies are maintained in reproductively skewed societies as well as revealing potential limitations of these mechanisms, emphasising the value of reproductively plastic social insects as models for the evolution of sociality.

Download activity - last month

Export as JSONCSVXML

Download activity - last 12 months

Export as JSONCSVXML

Downloads by country - last 12 months

Export as JSONXMLCSV

Archive Staff Only

View Item