PT  - JOURNAL ARTICLE
AU  - Edward Susko
AU  - Mike Steel
AU  - Andrew J. Roger
TI  - Conditions under which distributions of edge length ratios on phylogenetic trees can be used to order evolutionary events
AID  - 10.1101/2021.01.16.426961
DP  - 2021 Jan 01
TA  - bioRxiv
PG  - 2021.01.16.426961
4099  - http://biorxiv.org/content/early/2021/01/19/2021.01.16.426961.short
4100  - http://biorxiv.org/content/early/2021/01/19/2021.01.16.426961.full
AB  - Two recent high profile studies have attempted to use edge (branch) length ratios from large sets of phylogenetic trees to determine the relative ages of genes of different origins in the evolution of eukaryotic cells. This approach can be straightforwardly justified if substitution rates are constant over the tree for a given protein. However, such strict molecular clock assumptions are not expected to hold on the billion-year timescale. Here we propose an alternative set of conditions under which comparisons of edge length distributions from multiple sets of phylogenies of proteins with different origins can be validly used to discern the order of their origins. We also point out scenarios where these conditions are not expected to hold and caution is warranted.Competing Interest StatementThe authors have declared no competing interest.