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).