How do greenbeard kin recognition signals evolve?

Theme: Evolution & Adaptation

Primary Supervisor:

Chris Thompson

Genetics, Evolution and Environment, UCL

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Secondary Supervisor:

David Murrell

Genetics, Evolution and Environment, UCL

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Additional Supervisor(s):
Jason Wolf (University of Bath)

Project Description:

Organisms often make costly self-sacrifices to benefit others (e.g. watching for predators; public goods production). But why not simply freeload on the sacrifices made by others? One solution is that individuals direct help toward relatives that carry common genes (kin recognition). But how do individuals recognise relatives, and how does this elicit helping behaviour? The ‘greenbeard’ locus, named after a Richard Dawkins thought experiment, provides an elegant solution. In this, a single gene produces a signal (a green beard), identifies that signal in others, and modifies behaviour to direct help towards other green bearded individuals. However, the ability of a single gene to perform all these tasks has been questioned. Furthermore, the greenbeard’s selective advantage should ultimately cause all individuals to acquire green beards, thus erasing useful information content (Crozier’s paradox). Consequently, social cues (such as nest sharing) are generally favoured over genetic cues in the regulation of kin recognition. Paradoxically, many greenbeard kin recognition systems have been discovered. We recently identified one in a social microbial model, Dictyostelium discoideum (Gruenheit et al. 2017). In this cooperative system some individuals sacrifice themselves and die to help the others in the group survive. They also adjust how much of a sacrifice they are willing to make depending on their relatedness to their group (e.g. less when not with relatives) (Madgwick et al. 2018). This project will use modelling, genomics and cutting-edge molecular tools to understand how and why greenbeard systems evolve to control recognition and elicit this behavioural response.

Policy Impact of Research:

The project provides an unprecedented opportunity to understand the evolution and control of cooperative behaviour. You will test the idea that greenbeard sequence variation allows interacting individuals to measure gene sharing and use the degree of gene sharing to determine their level of cooperative self-sacrifice.

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