The generalistInga subnudasubsp.luschnathiana(Fabaceae): negative effect of floral visitors on reproductive success?

Abstract

Inga species are characterised by generalist or mixed pollination system. However, this feature does not enhance reproductive rates in species with very low fruit set under natural conditions. Some ecological and genetic factors are associated with this feature, and to test the effect of massive visits on pollination success in Inga subnuda subsp. luschnathiana, we studied the efficacy of polyads deposited on stigmas of flowers isolated from visitors and polyads exposed to visitors. The proportion of polyads fixed in stigmas decreased after exposure to visitors (24 h) in comparison to stigmas isolated from visitors (hummingbirds, bees, wasps, hawkmoths and bats), and fruit set was very low. Furthermore, nectar production, sugar composition and other floral biology traits were evaluated. Increased nectar production, sugar availability and sucrose dominance during the night indicates adaptation to nocturnal visitors and supports their role as main pollinators; although the brush-flower morphology, time of anthesis, nectar dynamics and chemical composition also allow daytime visitors. Thus the species is an important resource for a diverse group of floral visitors. We conclude that excess visits (diurnal and nocturnal) are responsible for the decrease in fixed polyads in stigmas of I. subnuda subsp. luschnathiana flowers, thus contributing, with others factors, to its low fruit set. Therefore, the generalist pollination system does not result in reproductive advantages because the low fruit set in natural conditions could be the result of a negative effect of visitors/pollinators.

Pollination by the locally endangered island flying fox (Pteropus hypomelanus) enhances fruit production of the economically important durian (Durio zibethinus)

“…Such a scenario was observed by Wilmott and Búrquez () for the self‐incompatible desert climbing vine Merremia palmeri of Mexico, where more than five visits by its primary pollinator actually resulted in lower fruit set. A similar effect has been postulated by Avila, Pinheiro, and Sazima () for the generalist forest tree Inga subnuda luschnathiana in Brazil, where visitations by animals to flowers resulted in decreased fixed polyads in stigmas. If a similar scenario occurs for durian, P. hypomelanus may not have had this effect in our study since it fed solitarily, occupied the same branch for extended lengths of time even when not feeding, and due to its territorial feeding behavior would have defended its floral resources against other visitors.…”

Floral traits driving reproductive isolation of two co-flowering taxa that share vertebrate pollinators

“…2015 ). Negative effect has been rarely observed in terms of fruit and seed set, as reported to Inga ( Avila et al . 2015 ).…”

Floral and reproductive biology of Matisia cordata (fam: malvaceae)

“…The possibility of adapting to changing conditions is one of the advantages of generalist pollination system (AVILA et al, 2015). In species such as sapoti, which has a limited flowering period per year, it is possible that the best strategy to assure fecundation is to attract as many pollinators as possible during the short flowering period.…”