PT  - JOURNAL ARTICLE
AU  - Rui Borges
AU  - Bastien Boussau
AU  - Gergely J. Szöllősi
AU  - Carolin Kosiol
TI  - Pervasive selection biases inferences of the species tree
AID  - 10.1101/2020.07.30.228965
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.07.30.228965
4099  - http://biorxiv.org/content/early/2020/07/31/2020.07.30.228965.short
4100  - http://biorxiv.org/content/early/2020/07/31/2020.07.30.228965.full
AB  - Despite the importance of natural selection in species’ evolutionary history, phylogenetic methods that take into account population-level processes ignore selection. Assuming neutrality is often based on the idea that selection occurs at a minority of loci in the genome and is unlikely to significantly compromise phylogenetic inferences. However, selection might behave more pervasively, as it the case of nearly neutral evolving mutations. Genome-wide processes like GC-bias and some of the variation segregating at the coding regions are known to evolve in the nearly neutral range. As we are now using genome-wide data to estimate species tree, it is just natural to ask whether weak, but pervasive, selection is likely to blur species tree inferences. Here, we employed a polymorphism-aware phylogenetic model, specially tailored for measuring signatures of nucleotide usage biases, to test the impact of nearly neutrally in the substitution process. Analyses with simulated data indicate that while the inferred relationships among species are not significantly compromised, the genetic distances are systematically underestimated, with the deeper nodes suffering more than the younger ones. Such biases have implications for molecular dating. We found signatures of GC-bias considerably affecting the estimated divergence times (up to 21%) of worldwide fruit fly populations. Our findings call for the need to account for nearly neutral forces (or any other form of pervasive selection) when quantifying divergence or dating species evolution.Competing Interest StatementThe authors have declared no competing interest.