Speaker
Berenike Maier
Description
Horizontal gene transfer is an important factor in bacterial evolution
that can act across
species boundaries. Yet, we know little about rate and genomic targets
of cross-species gene transfer, and on its physiological and selective
effects in the recipient organism. Here we address these questions in a
parallel evolution experiment with two Bacillus subtilis subspecies of
6.8% sequence divergence. We observe rapid evolution of hybrids by
lateral gene transfer, and we show that these dynamics involve
physiological and evolutionary adaptation. The genome-wide uptake of
orthologous genes, together with insertions and deletions of accessory
genes and de-novo mutations, generates genome evolution. Each
recipient population replaces about 12% of its core genes, and 51% of
core genes are replaced in at least one population. While evolved
hybrids show a net loss of gene expression compared to the ancestral
recipient population, we identify a set of genes whose upregulation is
predictive of hybrid fitness. Moreover, the co-occurrence statistics of
orthologous transfers reveals a broad network of fitness epistasis
between essential genes. Together, these results show that gene
transfer can bridge epistatic barriers between closely related species
along multiple high-fitness paths.
Primary author
Berenike Maier
