Figure 2.

Sample set of individuals from a Populus (poplar and aspen) species complex used for whole-genome phylogenomics. (a) Sampling locations of six Eurasian Populus species. (b) PCA of SNP data from resequenced genomes for seven Populus species, including the six Eurasian species (a) and one North American species, P. tremuloides. (c) Rooted NJ tree based on the genomic data, with P. trichocarpa and P. balsamifera as outgroups. (1) and (2) highlight the taxa selected for focused phylogenomic analysis in early stages of speciation (1) and late stages of speciation (2) as determined by IBD tract sharing (figure 3a). Species abbreviations: pade, P. adenopoda; palb, P. alba; pdav, P. davidiana; pqio, P. qiongdaoensis; prot, P. rotundifolia; ptma, P. tremula; ptmd, P. tremuloides; pbal, P. balsamifera; ptri, P. trichocarpa.