title: Molecular heterochrony and the evolution of sociality in bumblebees (Bombus terrestris).
abstract: Sibling care is a hallmark of social insects, but its evolution remains challenging to explain at the molecular level. The hypothesis that sibling care evolved from ancestral maternal care in primitively eusocial insects has been elaborated to involve heterochronic changes in gene expression. This elaboration leads to the prediction that workers in these species will show patterns of gene expression more similar to foundress queens, who express maternal care behaviour, than to established queens engaged solely in reproductive behaviour. We tested this idea in bumblebees (Bombus terrestris) using a microarray platform with approximately 4500 genes. Unlike the wasp Polistes metricus, in which support for the above prediction has been obtained, we found that patterns of brain gene expression in foundress and queen bumblebees were more similar to each other than to workers. Comparisons of differentially expressed genes derived from this study and gene lists from microarray studies in Polistes and the honeybee Apis mellifera yielded a shared set of genes involved in the regulation of related social behaviours across independent eusocial lineages. Together, these results suggest that multiple independent evolutions of eusociality in the insects might have involved different evolutionary routes, but nevertheless involved some similarities at the molecular level.
authors.affiliation: Department of Integrative Biology, University of Texas at Austin, , Austin, TX 78712, USA, Department of Ecology, Evolution and Behavior, Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, , Jerusalem 91904, Israel, W. M. Keck Center for Comparative and Functional Genomics, University of Illinois, , Urbana, IL 61801, USA, Department of Entomology, University of Illinois, , Urbana, IL 61801, USA, Institute for Genomic Biology, University of Illinois, , Urbana, IL 61801, USA, Neuroscience Program, University of Illinois, , Urbana, IL 61801, USA.
authors.forename: S Hollis
authors.initials: SH
authors.lastname: Woodard
authors.forename: Guy M
authors.initials: GM
authors.lastname: Bloch
authors.forename: Mark R
authors.initials: MR
authors.lastname: Band
authors.forename: Gene E
authors.initials: GE
authors.lastname: Robinson
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001516:Bees / Q000235:genetics / Q000502:physiology*; D001522:Behavior, Animal; D005075:Biological Evolution; D020869:Gene Expression Profiling; D017344:Genes, Insect; D006608:Hierarchy, Social; D020411:Oligonucleotide Array Sequence Analysis; D012919:Social Behavior; D013045:Species Specificity; D014863:Wasps / Q000235:genetics / Q000502:physiology
keywords: bumblebees; cooperative brood care; eusociality; gene expression; microarrays