Floral biology, nectar secretion pattern and fruit set of a threatened Bignoniaceae tree from Brazilian tropical forest

Abstract

Zeyheria tuberculosa, a Bignoniaceae tree that occurs in a broad latitudinal range in Brazilian forests, is a threatened species of seasonal tropical forest. It is crucial to enhance the knowledge on this species’ floral biology, since interactions related to reproduction of plants are critical for the long term maintenance of their populations. Thus, we investigated the sexual reproduction and floral biology of Z. tuberculosa, focusing on nectar features, aiming to understand the ecological processes associated to this mutualistic plant-animal interaction in the current modified landscape. For this, we performed experiments under natural conditions and laboratory. All the evaluated plants were self-incompatible. Zeyheria tuberculosa was pollinated by Bombus pauloensis, a medium-sized bee, and offered hexose-rich nectar as resource. Flowers were also visited by small-sized bee species, Trigona spinipes, that acted as pollen thief, and Pseudoaugochlora pandora and P. graminae that acted as nectar thieves. These three bee groups exhibited temporal separation in the peak of visits throughout the day. The peak of pollinator visits occurred firstly, which may allow the pollinator to access nectar and pollen loads before they are exploited by thieves. However, bee pollinator visits were scarce, and this fact, associated to the self-incompatibility of Z. tuberculosa, may explain the low fruit set registered in the studied plants. It could be of special concern for this threatened species maintenance in the medium and long term, which depends on the offspring originated by sexual reproduction

Nectar Replaced by Volatile Secretion: A Potential New Role for Nectarless Flowers in a Bee-Pollinated Plant Species

“…The causes of this variation in nectar production rhythm in J. oxyphylla flowers are yet unknown. Most bee-pollinated Bignoniaceae species start nectar production before anthesis ( Galetto, 1995 ; Lopes et al, 2002 ; Maués et al, 2008 ; Guimarães et al, 2016 ; Quinalha et al, 2017 ; Souza et al, 2017 ), so that pollinators have high probability of finding nectar in freshly opened flowers. However, in J. oxyphylla , when searching for nectar in recently opened flowers, pollinators have a 78% chance of finding empty flowers, considering that 47% of flowers are nectarless and 31% start nectar release just in the second day of anthesis (‘late’ flowers).…”

Are food‐deceptive orchid species really functionally specialized for pollinators?

“…simia to be more functionally generalized for pollinators than expected from the phenotypic point of view. According to Ollerton et al (2009), primary pollinators can be predicted by the floral pheno- (Fantinato et al 2016a;Stebbins 1970), implying that floral characteristics should reflect adaptation to the pollinator that transfers the most pollen (Mayfield 2001;Souza et al 2017). However, specific floral traits for the most common guild of visitors, or the one most effective in transferring pollen, may not preclude visits by less efficient floral visitors (i.e., secondary pollinators; Stebbins 1970), which in many cases have been proven to contribute to pollination (Rosas-Guerrero et al 2014).…”

Persistence of pollination‐mutualisms under the effect of intermediary resource

“…Therefore, nectar plays an important role in the prosperity of pollination‐mutualisms. For additional relevant works, we refer to Wang, DeAngelis, and Holland (2012), Georgelin and Loeuille (2014), Rojas‐Nossa, Sanchez, and Navarro (2016), Souza, Nepi, Machado, and Guimaraes (2017), Ren, Zhu, and Wang (2019), Tan, Wang, and Wu (2019), Wang (2019), Wang and Wu (2019), and so forth.…”

“…and Holland (2012), Georgelin and Loeuille (2014), Rojas-Nossa, Sanchez, and Navarro (2016), Souza, Nepi, Machado, and Guimaraes (2017), Ren, Zhu, and Wang (2019), Tan, Wang, and Wu (2019), Wang (2019), Wang and Wu (2019), and so forth. Revilla (2015) established a model to describe pollination-mutualisms, in which plant, nectar, and pollinator are included.…”