Theory of genomic imprinting conflict in social insects

David C Queller

doi:10.1186/1471-2148-3-15

Abstract

BackgroundGenomic imprinting refers to the differential expression of genes inherited from the mother and father (matrigenes and patrigenes). The kinship theory of genomic imprinting treats parent-specific gene expression as products of within-genome conflict. Specifically, matrigenes and patrigenes will be in conflict over treatment of relatives to which they are differently related. Haplodiploid females have many such relatives, and social insects have many contexts in which they affect relatives, so haplodiploid social insects are prime candidates for tests of the kinship theory of imprinting.ResultsMatrigenic and patrigenic relatednesses are derived for individuals affected in a variety of contexts, including queen competition, sex ratio, worker laying of male eggs and policing, colony fission, and adoption of new queens. Numerous predictions emerge for what contexts should elicit imprinting, which individuals and tissues will show it, and the direction of imprinting effects. The predictions often vary for different genetic structures (varying queen and mate number) and often contrast with predictions for diploids.ConclusionBecause the contexts differ from the normal imprinting case, and because nothing is currently known about imprinting in social insects, these predictions can serve as a strong a priori test of the kinship theory of imprinting. If the predictions are correct, then social insects, which have long served as exemplars of cooperation between individuals, will also be shown to be extraordinary examples of competition within individual genomes.

Highlights

Genomic imprinting refers to the differential expression of genes inherited from the mother and father
Transposons that jump to other places in the genome can spread though increased copy number even at some cost to their bearer. Genomic imprinting provides another likely case of within-genome conflict
Haig [14] first proposed that haplodiploidy would make social insects prone to imprinting effects for both sex ratio and for helping behavior

Summary

Introduction

Genomic imprinting refers to the differential expression of genes inherited from the mother and father (matrigenes and patrigenes). The kinship theory of genomic imprinting treats parent-specific gene expression as products of within-genome conflict. Transposons that jump to other places in the genome can spread though increased copy number even at some cost to their bearer. Genomic imprinting provides another likely case of within-genome conflict. An imprinted gene is one with parent-specific gene expression; it is expressed differently according to whether it was inherited from the mother or the father [4]. Whether or not a parent methylates a particular gene in the germ line may affect its expression in the offspring by altering the binding of enhancers or repressors

Results

Discussion

Conclusion