Ghost lineages can invalidate or even reverse findings regarding gene flow

• Published in: PLoS biology Vol. 20; no. 9; p. e3001776
• Main Authors: Tricou, Théo, Tannier, Eric, de Vienne, Damien M.
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 14.09.2022; Public Library of Science (PLoS)
• Subjects: Bioinformatics; Biological Evolution; Biology and Life Sciences; Computer and Information Sciences; Computer Science; Discovery Report; Endangered & extinct species; Evolutionary genetics; Gene Flow; Gene transfer; Genes; Genetic research; Genome; Genomes; Ghosts; Malaria; Phylogenetics; Phylogeny; Statistical analysis; Statistical tests; Taxonomy; Trees; Vector-borne diseases; Vectors; France
• ISSN: 1545-7885; 1544-9173; 1545-7885
• DOI: 10.1371/journal.pbio.3001776

Introgression, endosymbiosis, and gene transfer, i.e., horizontal gene flow (HGF), are primordial sources of innovation in all domains of life. Our knowledge on HGF relies on detection methods that exploit some of its signatures left on extant genomes. One of them is the effect of HGF on branch lengths of constructed phylogenies. This signature has been formalized in statistical tests for HGF detection and used for example to detect massive adaptive gene flows in malaria vectors or to order evolutionary events involved in eukaryogenesis. However, these studies rely on the assumption that ghost lineages (all unsampled extant and extinct taxa) have little influence. We demonstrate here with simulations and data reanalysis that when considering the more realistic condition that unsampled taxa are legion compared to sampled ones, the conclusion of these studies become unfounded or even reversed. This illustrates the necessity to recognize the existence of ghosts in evolutionary studies.