Wind or insect pollination? Ambophily in a subtropical gymnosperm Gnetum parvifolium (Gnetales)

Abstract

Gnetum (Gnetales) has long been regarded as insect pollinated due to its range-restricted distribution in tropical rain forests, where wind pollination is supposed to be detrimental. However, ubiquitous pollen limitation in the tropics might cause transition to anemophily, or even ambophily for reproductive assurance, especially for gymnosperms such as Gnetum, which exhibit various anemophilous syndromes, including absence of petals, greenish color of strobili, dioecy and uniovulate flowers. Pollination treatments applied to Gnetum parvifolium in southern China revealed this rare and endangered species to be pollen limited and incapable of apomixis. Pollen grains of G. parvifolium did not adhere to each other and could be trapped by interception traps near the male and female strobili. Seed set in the netted treatment (anemophily) was significantly higher than in the bagged treatment (apomixis) but lower than open pollination (anemophily and entomophily), indicating that both wind and biotic pollination contributed to seed production of G. parvifolium. The occurrence of ambophily in Gnetum and the prevalence of anemophily in Ehpedra and Welwitschia suggest that wind may also play a role in the pollination of the ancient Gnetales.

Single-Molecule Long-Read Sequencing Reveals the Diversity of Full-Length Transcripts in Leaves of Gnetum (Gnetales)

“…together form a monophyletic group-order Gnetales [1,2]. The phylogenetic relationship of the Gnetales with other seed plant groups has been a longstanding but controversial question of seed plant evolution [3][4][5][6][7]. On the basis of morphological and anatomical data, the Gnetales was inferred to be a sister group of angiosperms [2,8].…”

“…On the basis of morphological and anatomical data, the Gnetales was inferred to be a sister group of angiosperms [2,8]. However, the most recent molecular phylogenies have placed the Gnetales as a sister group to Pinaceae or entire conifers [3][4][5]9]. Genus Gnetum, comprising approximately 40 species, are woody climbers, with a few exceptions being shrubs and trees [1,10,11].…”

The Gnetales: Recent insights on their morphology, reproductive biology, chromosome numbers, biogeography, and divergence times

“…While wind pollination is the prevalent mode of pollination in extant Gnetales (Niklas & Buchmann, 1987;Kubitzki, 1990;Bolinder et al, 2015) and most gymnosperms (Takaso & Owens, 1996;Owens et al, 1998;Nepi et al, 2009), field observations and experimental studies have documented insect visitation in all three genera of the Gnetales. Specifically, small moths and flies feed on the pollination droplets of Gnetum, (Kato & Inoue, 1994;Kato et al, 1995;Gong et al, 2015), flies and beetles on those of Welwitschia (Pearson, 1907;Wetschnig, 1997;Wetschnig & Depisch, 1999), and small wasps, flies (Bino et al, 1984a(Bino et al, , 1984bBolinder et al, 2016), and ants of the subfamilies Formicidae and Myrmicinae on the droplets of Ephedra (Figs. 7A-7G; Bolinder et al, 2016).…”

Intensified wind pollination mediated by pollen dimorphism after range expansion in an ambophilous biennialAconitum gymnandrum

“…The frequency of ambophily is generally very low (Culley et al, 2002) but might be underestimated. For example, some plants that were once considered to be only wind pollinated or insect pollinated were identified to be pollinated by both wind and insect (Anderson, Overal, & Henderson, 1988;Gong et al, 2015;Peeters & Totland, 1999). Therefore, ambophily might represent an adaptation to different environments that vary in conditions favoring wind or animal pollination.…”