A global survey of eco-evolutionary pressures acting on horizontal gene transfer

Abstract

Abstract Horizontal gene transfer, the exchange of genetic material through means other than reproduction, is a fundamental force in prokaryotic genome evolution. Genomic persistence of horizontally transferred genes has been shown to be influenced by both ecological and evolutionary factors. However, the limited availability of ecological information apart from species’ isolation sources prevented deeper exploration of ecological contributions to horizontal gene transfer. Here, we assessed extensive ecological profiles of gene-exchanging organisms, focusing on transfers detected through explicit phylogenetic methods. By analysing the observed horizontal gene transfer events, we show distinct functional profiles for recent versus old events. Although most genes transferred are accessory, genes transferred earlier in evolution tend to be more ubiquitous within present-day species. Based on environmental information, we find that co-occurring, interacting, and high-abundance species tend to exchange more genes. Finally, we show that host-associated specialist species are much more likely to exchange genes with each other, while generalist species display less of a preference towards HGT with other species in their assigned habitat. Our study covers an unprecedented scale of integrated horizontal gene transfer and environmental information, highlighting broad eco-evolutionary trends.