Mixed Bat-Hummingbird Pollination Assures Reproductive Success in a Highly Variable Upper Montane Species

Area of Science:

• Ecology
• Botany
• Pollination Biology

Background:

• Callianthe sellowiana, a high-altitude Atlantic Forest endemic, displays floral traits suitable for both hummingbird (ornithophily) and bat (chiropterophily) pollination.
• Its reproductive system and the interplay between these pollination strategies remain largely unstudied.

Purpose of the Study:

• To investigate the reproductive system of Callianthe sellowiana and determine the contributions of bats and hummingbirds to its pollination success.
• To analyze floral traits in relation to pollinator visitation and visual perception.
• To understand the role of mixed pollination strategies in reproductive success and resilience.

Main Methods:

• Field observations and exclusion experiments were conducted in the Brazilian Atlantic Forest (2000m a.s.l.) to assess diurnal and nocturnal pollination contributions.
• Floral traits, including corolla shape and spectral reflectance, were analyzed.
• Pollen tube growth experiments were performed to evaluate self- vs. cross-pollen interactions.

Main Results:

• Both bats and hummingbirds contributed similarly to fruit and seed set, with no significant difference between diurnal and nocturnal exclusion treatments.
• Combined pollination (diurnal and nocturnal) resulted in higher reproductive success, indicating functional complementarity.
• Floral traits were adapted for both pollinators; spectral analysis showed low UV reflectance and peak red wavelengths, suitable for both visual systems.

Conclusions:

• Callianthe sellowiana employs a stable bimodal pollination strategy, leveraging functional and temporal complementarity between hummingbirds and bats.
• This mixed pollination strategy enhances reproductive success and resilience, potentially mitigating self-pollen interference in this self-incompatible species.
• The findings underscore the ecological importance of diverse pollinator interactions for plant reproductive success.