BIOINFORMATICS: PATTERNS OF GENE EXPRESSION

Correlating changes in patterns of gene expression that lead to different types of behaviour is the essential goal of the field of behavioural genetics, a field that is evolving from simple genetic mapping of behavioural mutants to sophisticated investigations of the influence of genes on behaviour, and of behaviour on genes.

Learning how genes influence the expression of altruism in social sweat bees is the fundamental goal of RICHARD's research. Halictine sweat bees are the most socially variable of any animal group, including species ranging from completely solitary to strongly eusocial, and even including facultatively social species. In all social species, newly emerged females are ‘totipotent’, that is, capable of acting as either queens or workers. Which caste they eventually join is strongly influenced by larval nutrition and genetic relationships among nestmates. By observing female sweat bees from larval to early adult stages, she can investigate how changes in gene expression influence and are influenced by the development of caste-specific behaviour. Particularly crucial is to investigate how different patterns of gene expression are associated with the expression of altruism, behaviour that typically is expressed only by workers. Recent technological advances in honeybee genomics have created molecular tools that can be used for sweat bee studies. At the DNA sequence level, strong similarities between honeybees and sweat bees allow her to use tools such as honeybee DNA chips to analyze gene expression patterns in sweat bees using microarray analysis. This means that elucidating genetic mechanisms determining behaviour, especially those underlying the specialized caste behaviours of queens and workers, is an achievable and worthwhile goal.

A second avenue of research is the use of DNA sequences for analyzing phylogenetic relationships among closely related sweat bee species, and in fact, for identification of cryptic species and subspecies, the existence of which greatly complicates the interpretation of behavioural data unless the species are confidently delineated. DNA sequence data are also being generated for molecular evolutionary studies of evolutionary rates (in terms of DNA and amino acid substitution rates) and mutational rates of haplodiploid vs diploid insects, a new line of research recently opened up in her research group.

RICHARDS is dealing with the mountains of microarray and DNA sequence data she is currently generating and studying. She is focusing on the development and expression of caste-specific behaviour in social sweat bees, using microarray analyses for both intra- and inter-specific comparisons of gene expression patterns. In honeybees and sweat bees, differences in larval nutrition appear to trigger a developmental switch that leads to the expression of the caste-specific behavioural repertoires. The timing of this switch and the nature of the genes that are turned off or on in queen- and worker-destined females will be investigated using microarray analysis of queen and worker-destined bees from early larvae to 3 days post-eclosion. Once candidate loci have been identified, the study will be enlarged to compare pairs of solitary vs. social sibling species to determine whether particular loci may be responsible for facultative variation in sociality.

For more information on her research please visit her homepage.