Extensive pollinator sharing does not promote character displacement in two orchid congeners

Abstract

Pollinator sharing between close relatives can be costly and can promote pollination niche partitioning and floral divergence.This should be reflected by a higher species divergence in sympatry than in allopatry. We tested this hypothesis in two orchid congeners with overlapping distributions and flowering times. We characterized floral traits and pollination niches and quantified pollen limitation in 15 pure and mixed populations, and we measured phenotypic selection on floral traits and performed controlled crosses in one mixed site. Most floral traits differed between species, yet pollinator sharing was extensive. Only the timing of scent emission diverged more in mixed sites than in pure sites, and this was not mirrored by the timing of pollinator visitation. We did not detect divergent selection on floral traits. Seed production was pollen limited in most populations but not more severely in mixed sites than in pure sites. Interspecific crosses produced the same or a higher proportion of viable seeds than intraspecific crosses. The two orchid species attract the same pollinator species despite showing divergent floral traits. However, this does not promote character displacement, implying a low cost of pollinator sharing. Our results highlight the importance of characterizing both traits and ecological niches in character displacement studies.

Digest: Extensive pollinator sharing does not promote character displacement in two orchid congeners

“…There was no difference in floral morphology or pollen limitation between pure and mixed sites for either species, potentially due to the limited flowering time overlap between the two This article corresponds to Joffard, N., Olofsson, C., Friberg, M., & Sletvold, N. (2022). Extensive pollinator sharing does not promote character displacement in two orchid congeners.…”

“…In this study, Joffard et al. (2022) examine two related orchid species ( Gymnadenia conopsea and Gymnadenia densiflora ) that share pollinators to test for evidence of increased trait divergence in communities where both species are present. They selected sites with either one or both species.…”

Fine‐scale genetic structure in the orchidGymnadenia conopseais not associated with local density of flowering plants

“…It is self compatible, but requires pollinators to produce fruits. In the study populations, pollination is mainly nocturnal, and the most frequent visitors are Deilephila porcellus (Sphingidae) and Autographa gamma (Noctuidae) (Joffard et al, 2022). Fruit set is usually high (60-100%), and a single fruit typically contains 300-1500 seeds that are dispersed by wind in late summer.…”

Triploid cultivars of Cymbidium act as a bridge in the formation of polyploid plants

“…It exhibits distinctive ecological diversification and occurs in terrestrial, epiphytic, lithophytic, and saprophytic life forms (Yukawa and Stern, 2002;Ning et al, 2018). The cross compatibility between different species was reported to be high, and even an increasing number of interspecific and intergeneric hybrids has been obtained through artificial pollination (Li et al, 2014;Ogura-Tsujita et al, 2014;Joffard et al, 2022). These interspecific hybrids have a high percentage in occurrence of 2n gametes and have been successfully employed to create sexual polyploids in breeding programs (Zeng et al, 2020;Kondo et al, 2022).…”