Unsampled ghost lineages can invalidate phylogenetic findings on horizontal gene flow
Researchers have shown that unsampled taxa, both extinct and living, can overturn conclusions about horizontal gene flow between species. The team used evolutionary simulations and reanalyzed published datasets on malaria vectors and eukaryogenesis. When they accounted for the reality that unsampled taxa far outnumber sampled ones, previous claims about massive adaptive gene flows became unfounded. In some cases the conclusions reversed entirely. The problem stems from how these ghost lineages affect branch lengths in constructed phylogenies, a signature that existing statistical tests rely on to detect introgression, endosymbiosis, and gene transfer.
Evolutionary models need to explicitly recognize the existence of ghost lineages when inferring horizontal gene transfer from genome sequences. Studies that assume unsampled taxa have little influence may reach incorrect conclusions about how genes move between species.
Written by the Genomes desk from the primary source cited and linked above and checked against it. Research use only; not medical advice. Corrections: [email protected].