Horizontal gene transfer drives the evolution of dependencies in bacteria [article]

Akshit Goyal
2019 bioRxiv   pre-print
Many naturally-occurring bacteria lead a lifestyle of metabolic dependency, i.e., they depend on others for crucial resources. We do not understand what factors drive bacteria towards this lifestyle, and how. Here, we systematically explain the role of horizontal gene transfer (HGT) in metabolic dependency evolution. Across 835 bacterial species, we map gene gain-loss dynamics on a deep evolutionary tree, and assess the impact of HGT and gene loss on bacterial metabolic networks. Our analyses
more » ... rks. Our analyses suggest that genes acquired by HGT can affect which genes are later lost. Dependency evolution by gene loss is contingent on earlier HGT via two steps. First, we find that HGT typically adds new catabolic routes to microbial metabolic networks. This increases the chance of new metabolic interactions between bacteria, which is a prerequisite for dependency evolution. Second, we show how gaining new routes can promote the loss of specific ancestral routes (a mechanism we call "coupled gains and losses", CGLs). Phylogenetic patterns indicate that both types of dependencies − those mediated by CGLs and those purely by gene loss − are equally likely. Our results highlight HGT as an important driver of metabolic dependency evolution in bacteria.
doi:10.1101/836403 fatcat:fbywb47i4fcnng3lip6f7443r4