Population structure and disparity
Population structuring was variable between species and clustering mostly reflected geographic relationships (Fig. 3, Fig. S5). Individuals of lowland bee-pollinated Ad. adscendens grouped into two distinct clusters (South-Western versus Northern Costa Rica, Fig. 1A, Fig. 3A). While admixture analyses supported two ancestral populations with low admixture, co-ancestry estimates revealed shared co-ancestry between the two geographic clusters (Fig. 3A). In bee-pollinatedM. maxima , individuals clustered into three distinct groups (Fig. 3B) despite relative geographic vicinity among all localities (Fig. 1). Admixture analyses detected three ancestral populations with low admixture (below 10%) and were supported by co-ancestry estimates (Fig. 3B). We also detected population clustering in hummingbird-bat-rodent-pollinated M. sanguinea (two clusters, Fig. 3D) and in hummingbird-bat-pollinated M. tomentosa (three clusters, Fig. 3E), representing distant localities in Northern and Southern Ecuador (Fig. 1). Admixture was mostly below 20% in both species, with highest probability of two ancestral populations, and low co-ancestry between the geographic clusters (Fig. 3D, E). Population structuring was weak and admixture high (ca. 30%) in hummingbird-bat-pollinated M. phlomoides (Fig. 3C) and passerine-pollinated A. costaricensis (Fig. 3F). We found highest likelihood for three ancestral populations in M. phlomoides , and two ancestral populations in A. costaricensis , and overall high shared co-ancestry across localities (Fig. 3C, F, Fig. S5).
In all species, at least some localities were significantly differentiated from each other (Tables S15, S16), but adjacent localities were generally not differentiated (Fig. 1). Genetic differentiation was weakest in passerine-pollinated A. costaricensis and highest in bee-pollinated Ad. adscendens . We detected most significant differences in genetic disparity among localities in Ad. adscendens (6/15 comparisons) and M. tomentosa (4-5/10 comparisons) and no differences in M. sanguinea and A. costaricensis (Table S17, S18). Compared to the other species, montane bee-pollinated M. maxima showed lowest disparity within localities (Fig. S5).