Jesper Smærup Bechsgaard
The evolution of sociality in spiders is expected to be accompanied by changes at the molecular level. Population genetic theory predicts that the structuring of genetic variation of highly inbreeding species will be different than for outbreeding species. Within populations diversity is expected to be low, whereas between populations diversity is expected to be high. The biology of social spiders (inbreeding, female biased sex ratio, meta-population structure) is expected to result in highly reduced effective population size and thereby less efficient selection. If so, it will leave footprints in the genomes of social spiders.
Very little molecular work has been done to test these predictions in social spiders. From transcriptome sequencing we have developed a catalog of about 1800 genes which can be used to e.g. design primers to be used across all species in the Stegodyphus genus.
We will take advantage of this catalog to build a precise and reliable molecular phylogeny as the basal framework for other molecular studies. We will investigate how genetic diversity is structured within and between populations and do comparisons between the social species and their sub-social sister species. Also, we will investigate if selection is relaxed in the social species by estimation of synonymous and non-synonymous diversity, and if so, if we can find footprints in the genomes by estimation of synonymous and non-synonymous divergence between species. We will use the obtained data to estimate when sociality evolved, to get an idea of the evolutionary stability of sociality.