A Genetic Locus Determining Altruism Identified in Microbial Eukaryotes

physorg |  Geneticists from the Universities of Manchester and Bath are celebrating the discovery of the elusive 'greenbeard gene' that helps explain why organisms are more likely to cooperate with some individuals than other.

The renowned evolutionary biologist Richard Dawkins coined the term "greenbeard gene" in his 1976 best seller The Selfish Gene.

The greenbeard is a special type of gene that, said Dawkins, could solve the conundrum of how organisms identify and direct selfless behaviour to towards other selfless individuals.

The existence of greenbeard genes once seemed improbable, but work published in Nature Communications by the team of geneticists has identified a gene that causes a whole range of 'beard colours' in a social microbe.

The microbes - 'slime moulds' - live as single celled organisms, but clump together to form a slug like creature when they run out of food. The newly formed slug can move to help them find new sources of food, but this depends on successful cooperation.

With funding from the Wellcome Trust, NERC and the BBSRC the research team found that slime mould cells are able to decide who they collaborate with. By sequencing their genomes, they discovered that partnership choices are based on a greenbeard gene.

The gene encodes a molecule that sits on the surface of a slime mould cell, and is able to bind to the same molecule in another slime mould cell.

Greenbeard genes stand out because they harbour enormous diversity, with most slime mould strains having a unique version of the gene.

The team discovered that individuals prefer to partner with those that have similar versions of the gene, and the slugs formed with preferred partners do better than those with non-preferred partners.

This demonstrates, according to the team, that there is a whole range 'beard colours' that function to identify compatible partners for cooperation.