Floral scent composition predicts bee pollination system in five butterfly bush (Buddleja, Scrophulariaceae) species

Abstract

Traditionally, plant-pollinator interactions have been interpreted as pollination syndrome. However, the validity of pollination syndrome has been widely doubted in modern studies of pollination ecology. The pollination ecology of five Asian Buddleja species, B. asiatica, B. crispa, B. forrestii, B. macrostachya and B. myriantha, in the Sino-Himalayan region in Asia, flowering in different local seasons, with scented inflorescences were investigated during 2011 and 2012. These five species exhibited diverse floral traits, with narrow and long corolla tubes and concealed nectar. According to their floral morphology, larger bees and Lepidoptera were expected to be the major pollinators. However, field observations showed that only larger bees (honeybee/bumblebee) were the primary pollinators, ranging from 77.95% to 97.90% of total visits. In this study, floral scents of each species were also analysed using coupled gas chromatography and mass spectrometry (GC-MS). Although the five Buddleja species emitted differentiated floral scent compositions, our results showed that floral scents of the five species are dominated by substances that can serve as attractive signals to bees, including species-specific scent compounds and principal compounds with larger relative amounts. This suggests that floral scent compositions are closely associated with the principal pollinator assemblages in these five species. Therefore, we conclude that floral scent compositions rather than floral morphology traits should be used to interpret plant-pollinator interactions in these Asian Buddleja species.

Natural Hybridization between Two Butterfly Bushes in Tibet: Dominance of F1 Hybrids Promotes Strong Reproductive Isolation

“…It has been hypothesized that it should be more common for the selfcompatible species to be the maternal parent [7] . Previous studies have con rmed self-compatibility in B. crispa from the substantial seed set attributed to geitonogamous pollination, similar to that following outcrossing when owers [29] , whereas no seeds were obtained in self-pollination treatments in B. alternifolia (Liao RL, unpublished data). Additionally, the peak owering time of B. crispa is earlier than B. alternifolia with only very limited overlap.…”

“…× wardii [1] . Sympatric distribution, overlapping owering periods (B. alternifolia ranging from April to June, while B. crispa from March to August) [27][28] (personal observation) and shared pollinators (bees, bumblebees and butter ies) [29] (personal observation) all facilitate natural hybridization between the two parental species. In addition, Buddleja in Asia is a young clade that began diversifying approximately 10 Ma during the uplift of the Himalayas, and reproductive isolation between them is still incomplete [16,30] .…”

Natural hybridization between two butterfly bushes in Tibet: dominance of F1 hybrids promotes strong reproductive isolation   

“…× wardii [1] . Sympatric distribution, overlapping owering periods (B. alternifolia ranging from April to June, while B. crispa from March to August) [27][28] (personal observation) and shared pollinators (bees, bumblebees and butter ies) [29] (personal observation) all facilitate natural hybridization between the two parental species. Another factor favoring natural hybridization between B. alternifolia and B. crispa was that they are both diploid with 2n = 38 [16] , which may facilitate hybridization [30][31] .…”

Genetic diversity and population structure of Buddleja crispa Bentham in the Himalaya-Hengduan Mountains region revealed by AFLP

“…Each individual is represented by a vertical bar, colored according to the assigned group(s). maintained by the species due to environmental heterogeneity (Ewing, 1979;Gillespie and Turelli, 1989;Yeaman and Jarvis, 2006). Thus, the different habitats in the HHM region might promote accumulation and accommodation of new mutations in B. crispa and enable it to adapt to a wide variety of habitats.…”