Population structure in Neotropical plants: integrating pollination
biology, topography and climatic niches
Abstract
Animal pollinators mediate gene flow among plant populations, but, in
contrast to well-studied topographic and (Pleistocene) environmental
isolating barriers, their impact on population genetic differentiation
remains largely unexplored. Comparatively investigating how these
multifarious factors drive microevolutionary histories is, however,
crucial for better resolving macroevolutionary patterns of plant
diversification. We here combined genomic analyses with landscape
genetics and niche modelling across six related Neotropical plant
species (424 individuals across 33 localities) differing in pollination
strategy to test the hypothesis that highly mobile (vertebrate)
pollinators more effectively link isolated localities than less mobile
(bee) pollinators. We found consistently higher genetic differentiation
(FST) among localities of bee- than vertebrate-pollinated species with
increasing geographic distance, topographic barriers and historic
climatic instability. High admixture among montane populations further
suggested relative climatic stability of Neotropical montane forests
during the Pleistocene. Overall, our results indicate that pollinators
may differentially impact the potential for allopatric speciation,
thereby critically influencing diversification histories at
macroevolutionary scales.