Biogeographical and phylogenetic constraints on horizontal gene transfer and genome evolution in <i>Streptomyces</i>

Horizontal gene transfer (HGT) is a vital ecological and evolutionary force in microbiology, but we still lack a precise understanding of how precisely HGT acts on the gene pool of a species or genus. While HGT can complicate phylogenetic analyses and assumptions of homology, its role in adaptation and acquiring secondary metabolites should not be overlooked. Microbial ecologists agree that the pangenome is a shifting collection of genes that can be influenced by both vertical inheritance and ecological factors. This study examines how the <i>Streptomyces</i> pangenome is shaped by these two forces and offers an important quantitative insight into how HGT shapes bacterial genome dynamics.