Maintenance of flower color dimorphism in Ophiorrhiza japonica (Rubiaceae): responses to fluctuating temperatures in a dolomite Karst region

Fluctuating temperatures, not pollinators, are the primary driver of flower color dimorphism in Ophiorrhiza japonica within the UNESCO-listed dolomite karst region of Shibing. Research compared pink and white flower morphs, finding no significant difference in pollinator visitation but a marked shift in their ratio between spring and winter. Temperature experiments revealed that pink flowers maintained higher temperatures at moderate ranges (0–24°C), while white flowers dominated at extreme cold (-4°C). These findings challenge traditional hypotheses linking color polymorphism to pollinator selection, instead supporting the pleiotropic effect hypothesis—where temperature directly influences flower coloration. The study provides a model for understanding such traits in karst ecosystems.

Wang, X.-Y., Tang, H.-Q., Liu, Y.-J., Xiang, M.-D., Yao, R.-X., Li, B.-Z., Li, Y., Yi, Y., Wen, Z.-R., Tang, M., & Tang, X.-X. (2024). Maintenance of flower color dimorphism in Ophiorrhiza japonica (Rubiaceae): responses to fluctuating temperatures in a dolomite Karst region. Frontiers in Plant Science, 15. https://doi.org/10.3389/fpls.2024.1495112