Pollinator Visitation Within a Single Crown of the Rare Rainforest Tree Firmiana daweishanensis Is Associated With Floral Colour Change
5 affiliations
- 1Yunnan Key Laboratory for Integrative Conservation of Plant Species With Extremely Small Populations, Kunming Institute of Botany Chinese Academy of Sciences Kunming China
- 2University of Chinese Academy of Sciences Beijing China
- 3Forestry and Grassland Bureau of Hekou County Hekou Yunnan China
- 4Maguan Gulinqing Provincial Nature Reserve Management and Protection Bureau Maguan Yunnan China
- 5State Key Laboratory of Plant Diversity and Specialty Crops, Kunming Institute of Botany Chinese Academy of Sciences Kunming China
Abstract
Floral colour change can signal floral state, but its role in rainforest canopy trees remains poorly understood. We investigated colour change and pollinator visitation in Firmiana daweishanensis , a Plant Species with Extremely Small Populations endemic to southeastern Yunnan, China. Using a 25‐m scaffold, we observed 16 flowering branches on one adult tree for 128 branch‐hours. We combined these observations with measurements of linalool emission, nectar accumulation, reproductive function, calyx reflectance and bee visual modelling. Six hymenopteran taxa visited the tree, with Megachile bees dominating visitation. Mixed models showed that yellow flowers received more visits and greater cumulative visitation time per flower‐hour than red flowers within both sexes. Neither the omnibus sex tests nor the colour × sex interactions were significant. Branch‐level floral abundance and colour composition were not significantly associated with visitation. This contrast was consistent with, but did not demonstrate, selection at a fine spatial scale; limited statistical power remained an alternative explanation. Yellow flowers showed higher linalool emission and stronger modelled green‐receptor contrast against a green background. Nectar availability and reproductive function were generally greater during earlier floral stages. Neither pollinator‐excluded nor artificially geitonogamously self‐pollinated flowers produced fruit, whereas naturally exposed flowers showed 6.19% fruit set. These observations support a contribution of floral visitors to fruit set, but the absence of a hand‐cross‐pollinated control prevented a conclusive assessment of self‐incompatibility. Because colour, age, scent, reward and reproductive state covaried, their individual contributions to visitation could not be distinguished. Floral colour change may therefore form part of a multimodal indicator of floral state, while any display function of retained red flowers remains hypothetical. This within‐tree case study documents canopy visitation patterns whose generality requires replication across individuals and populations.
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BibTeX
@article{wang2026pollinator,
title = {{Pollinator Visitation Within a Single Crown of the Rare Rainforest Tree Firmiana daweishanensis Is Associated With Floral Colour Change}},
author = {Bo‐Qiang Wang and Si‐Yue Xiao and Cheng‐Jie Li and Yan‐Mei Ping and Jin‐Guo Zhang and Wei‐Bang Sun and Jing Yang},
journal = {Ecology and evolution},
year = {2026},
month = oct,
doi = {10.1002/ece3.74490},
url = {https://europepmc.org/article/PMC/PMC13658850},
note = {CC BY},
}
RIS
TY - JOUR
TI - Pollinator Visitation Within a Single Crown of the Rare Rainforest Tree Firmiana daweishanensis Is Associated With Floral Colour Change
AU - Bo‐Qiang Wang
AU - Si‐Yue Xiao
AU - Cheng‐Jie Li
AU - Yan‐Mei Ping
AU - Jin‐Guo Zhang
AU - Wei‐Bang Sun
AU - Jing Yang
PY - 2026
DA - 2026/10/01
JO - Ecology and evolution
DO - 10.1002/ece3.74490
UR - https://europepmc.org/article/PMC/PMC13658850
AB - Floral colour change can signal floral state, but its role in rainforest canopy trees remains poorly understood. We investigated colour change and pollinator visitation in Firmiana daweishanensis , a Plant Species with Extremely Small Populations endemic to southeastern Yunnan, China. Using a 25‐m scaffold, we observed 16 flowering branches on one adult tree for 128 branch‐hours. We combined these observations with measurements of linalool emission, nectar accumulation, reproductive function, calyx reflectance and bee visual modelling. Six hymenopteran taxa visited the tree, with Megachile bees dominating visitation. Mixed models showed that yellow flowers received more visits and greater cumulative visitation time per flower‐hour than red flowers within both sexes. Neither the omnibus sex tests nor the colour × sex interactions were significant. Branch‐level floral abundance and colour composition were not significantly associated with visitation. This contrast was consistent with, but did not demonstrate, selection at a fine spatial scale; limited statistical power remained an alternative explanation. Yellow flowers showed higher linalool emission and stronger modelled green‐receptor contrast against a green background. Nectar availability and reproductive function were generally greater during earlier floral stages. Neither pollinator‐excluded nor artificially geitonogamously self‐pollinated flowers produced fruit, whereas naturally exposed flowers showed 6.19% fruit set. These observations support a contribution of floral visitors to fruit set, but the absence of a hand‐cross‐pollinated control prevented a conclusive assessment of self‐incompatibility. Because colour, age, scent, reward and reproductive state covaried, their individual contributions to visitation could not be distinguished. Floral colour change may therefore form part of a multimodal indicator of floral state, while any display function of retained red flowers remains hypothetical. This within‐tree case study documents canopy visitation patterns whose generality requires replication across individuals and populations.
SN - 2045-7758
ER -