Arrival of the fittest: examining the underlying mechanisms of morphological plasticity in an adaptive radiation

Phenotypic plasticity has become a central topic in evolutionary biology which is studied for its role in generating adaptive variation. Yet, despite a rapidly growing interest there is still little known about the underlying mechanisms of plasticity. This project will focus on uncovering some of these mechanisms using adaptive radiation in African cichlids. Cichlids are an exemplar system for evolution because they are derived from a recent common ancestor but exhibit vast amounts of adaptive skeletal variation controlled by few mutations on a common genetic background. We have previously uncovered candidate ‘plasticity genes’ that act within the craniofacial region. These genes have been implicated in bone development but also as potential role players in alternative mechanisms for mechanosensory function. The student would take these results forward with a series of exciting investigations in the lab and field aimed at understanding the molecular and cellular mechanisms involved in plasticity.

Specifically, the PhD candidate will aim to address three key questions:
1) What mechanisms underly species differences in plasticity?
2) Does bone plasticity rely on a range of mechanosensory mechanisms?
3) Are mechanisms of plasticity active in natural populations of cichlids?

Methodology
The student will learn a range of cutting edge techniques in the lab and be in charge of running plasticity experiments on different species of cichlids. This will include a focus on assessing responses in head morphology and associated bones using established protocols. These experiments will be used with a set of lab techniques to understand the molecular and cellular mechanisms of plastic responses. This will include targeting candidate genes for expression analysis using qPCR at different phases of the plastic response. However, this project will break new ground through the use of novel approaches that will allow for cichlid bone cells to be cultured and mechanically stressed in vitro (i.e. ‘nanokicking’) through approaches developed by Dalby. This approach greatly enhances the resolution of experiments by allowing specific bones to be targeted and responses compared. Finally, we have determined that the primary mode of adaptive divergence involve the lengthening and shortening of the oral jaws. This allows us to make predictions about the degree of plasticity whereby species at the extremes of morphospace should be less plastic than intermediate forms. This will be tested in the lab through experiments but the activity of identified genes will also be assessed in different species through field collections by the student in Africa.

Timeline
Funding is for 3.5 years with a 4 deadline to completion
Year 1- rearing of cichlids under different foraging treatments
- Collection of material for qPCR
- Establishment of in vitro protocols
Year 2 – measurement of gene expression
- Measurement from in vitro assays
- Measurement of morphometric variation
Year 3 - Field trip and collections in Africa (Malawi)
- Follow up lab work for field material
- completion of data collection
Analysis of data and writing of chapters

Training & Skills
The candidate will learn a broad range of transferable skills that will enhance his or her prospects and prepare them for a career in academia or industry. These skills include fish husbandry, data management and manipulation, fluorescent microscopy, molecular biology and genetic techniques, morphometrics and multivariate statistics. The student would also gain an understanding of functional morphology in skeletal systems and bone biology. In addition, the field work will enhance the candidate’s experience of international fieldwork and the regulatory landscape surrounding research in the tropics. We will take advantage of the close proximity of the supervisors to ensure frequent meetings, and the candidate will also profit from exposure to the extended networks of the collaborating team.