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  1. Interactions between species can influence access to resources and successful reproduction. One possible outcome of such interactions is reproductive character displacement. Here, the similarity of reproductive traits – such as flowering time – among close relatives growing in sympatry differ more so than when growing apart. However, evidence for the overall prevalence and direction of this phenomenon, or the stability of such differences under environmental change, remains untested across large taxonomic and spatial scales. We apply data from tens of thousands of herbarium specimens to examine character displacement in flowering time across 110 animal-pollinated angiosperm species in the eastern USA. We demonstrate that the degree and direction of phenological displacement among co-occurring closely related species pairs varies tremendously. Overall, flowering time displacement in sympatry is not common. However, displacement is generally greater among species pairs that flower close in time, regardless of direction. We additionally identify that future climate change may alter the nature of phenological displacement among many of these species pairs. On average, flowering times of closely related species were predicted to shift further apart by the mid-21st century, which may have significant future consequences for species interactions and gene flow.Competing Interest StatementThe authors have declared no competingmore »interest.« less
  2. Abstract
    Reproductive character displacement has long been hypothesized to be a key determinant of speciation and co-existence in flowering plants. A central tenet of this hypothesis is that reproductive traits of close relatives growing in sympatry diverge more than they do where close relatives do not grow together. However, this idea remains untested across taxa and at large spatial scales. Here, we use data collected from tens of thousands of herbarium specimens to examine evidence for character displacement in flowering time for 91 closely-related pairs of animal-pollinated angiosperm species in the eastern USA. We see no evidence for overall phenological divergence in sympatry across regions, clades, or life histories. Rather our results indicate widespread convergence of flowering times in sympatry for species pairs that generally tend to flower close in time. We also find that climate change could alter the nature of these convergent flowering events by shifting them further apart in a majority species pair comparisons. Specifically, congeneric species in New England and the Atlantic Coastal Plain are projected to flower 2–4 days further apart, on average, by the mid-21st century as warming temperatures drive species-specific phenological shifts within genera. This may have significant consequences for species interactions andMore>>
  3. Record, Sydne (Ed.)