Possible tobacco progenitors share long-tongued hawkmoths as pollen vectors

Abstract

The putative ancestors of the allopolyploid hybrid Nicotiana tabacum have distinct flower features, apparently suited either for hawkmoth or bat pollination. This suggests that progenitors were reproductively isolated by mechanical and ethological barriers. However, the present data show that in natural populations pollen vectors could be shared by two of the possible progenitors. Pollen vectors of one of the possible male progenitors (N. otophora) were short- and long-tongued hawkmoths and a nectar-feeding bat, while those of the female ancestor (N. sylvestris) were only long-tongued hawkmoths. The latter are then the most likely vectors responsible for the presumed spontaneous hybridization. These data also suggest that interspecific pollen transfer occurred more likely in one direction.