Excess allele sharing and gene flow events among guenons. (A) D-statistic (circles) and f4-ratios (diamonds) as estimated by Dsuite illustrating excess of allele sharing caused by the 7 identified gene flow events. The combinations of tested taxa are shown on the left (with M. mulatta as outgroup). Positive D-statistic values indicate gene flow between P3 and P2 taxa and are connected by lines to the f4-ratios that reflect the proportion of gene flow. The values were obtained for all possible members of the respective species groups, for which more than a single representative was available in our dataset. In events C and E, we observed decreasing D-statistics with more closely related P1 taxa (annotated as dashed shapes), indicating directionality from P2 into P3. (B) Schematic overview of the identified gene flow events. Arrows are shown where directionality could be inferred. Mitochondrial introgressions, accompanying nuclear gene flow between internal branches, are shown as dashed circles with an arrow. Dashed circles on tips highlight species that carry an introgressed mitochondrion, with circle color corresponding to the most likely introgression event. The donor in B2 was not fully resolved, as illustrated by the question mark, and the dashed line of the C. cephus/ascanius divergence illustrates the likely overestimate of this node's age (see main text). Where available, annotations to the right of species labels show the chromosome number of extant species. (C) Schematic overview of the minimum time since divergence at the time of introgression, based on the divergence time estimates. The divergence time estimate between the eastern and western populations of C. mona was retrieved from Ayoola et al. (2021).