Abstracts (first author)
Genomic adaptation to different hosts - What makes better-adapted viruses?
The interplay between ecological and genomic adaptation is at the heart of evolutionary processes. If we consider that species evolve as groups of genomes adapting to particular ecological niches, shifts to a new ecological niche should be connected with the adaptation and differentiation of a genome population to this particular niche. To study how ecological adaptation affects genomes simultaneously at both ecological and whole genome levels, we focussed on large DNA viruses because their ecological niches are mostly defined by their hosts. Among viruses, baculoviruses are uniquely transmitted between insect hosts as groups of genomes, which sets them further apart for studying the effect of niches on populations. We investigated this question of ecological genomic adaptation by an experimental evolution approach on a baculovirus. As their infectious particles contain >100 virions each enclosing a genome of 134 kb, baculoviruses foster the maintenance of high genetic diversity, as we discovered from ultra-deep illumina sequencing of the AcMNPV wild-type isolate. We found different level of polymorphism: few SNPs at high frequency located in essential genes involved in replication, transcription and transmission, and low frequency SNPs in every position, suggesting any potentially beneficial mutation is already present within the population. We used this diverse virus population to perform experimental evolution in two lepidopteran host species Trichoplusia ni and Spodoptera exigua. We performed 10 infection cycles in 10 replicate lines. We analysed the evolution of virulence phenotypes in parallel to resequencing the evolved progeny lines.