RT Journal Article
SR Electronic
T1 Evolutionary jumps in bacterial GC content
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2021.02.16.431469
DO 10.1101/2021.02.16.431469
A1 Saurabh Mahajan
A1 Deepa Agashe
YR 2021
UL http://biorxiv.org/content/early/2021/02/17/2021.02.16.431469.abstract
AB The diversity of bacterial GC content (ranging from 13-75%) has been studied for many decades, yet its evolution remains incompletely understood. Since it is difficult to observe GC content evolve on realistic time scales in the laboratory, comparative approaches are instrumental for its study. Additionally, investigating phylogenetic patterns in a trait’s diversity can provide greater insight into its evolution; but this dimension is rarely studied systematically in the case of bacterial GC content. Therefore, we applied phylogenetic models – typically used for studying morphological or behavioral traits of animals and plants – to the study of this fundamental molecular trait. We find that GC content diversifies via a combination of gradual evolution and evolutionary “jumps” in multiple bacterial groups across two major bacterial phyla. In a systematic survey of these GC content jumps, we retrieved many well-studied cases of severe evolutionary reduction in GC content of endosymbiotic bacteria, but also identified GC content jumps in bacterial lineages beyond such peculiar contexts. Surprisingly, unlike prior reports that solely focused on reductions in GC, we found a comparable number of jumps with both increased and decreased GC content. Our preliminary analysis of potential ecological explanations of GC jumps suggests that most of these GC jumps are not concomitant with changes in previously implicated factors such as host association or oxygen dependence. Thus, the ecological and evolutionary drivers of rapid and large shifts in GC content remain open questions. Our systematic identification of bacterial lineages experiencing GC jumps provides new datasets and novel contexts to address these questions.Competing Interest StatementThe authors have declared no competing interest.