title: Convergent Evolution towards High Net Carbon Gain Efficiency Contributes to the Shade Tolerance of Palms (Arecaceae).
abstract: Most palm species occur in the shaded lower strata of tropical rain forests, but how their traits relate to shade adaptation is poorly understood. We hypothesized that palms are adapted to the shade of their native habitats by convergent evolution towards high net carbon gain efficiency (CGEn), which is given by the maximum photosynthetic rate to dark respiration rate ratio. Leaf mass per area, maximum photosynthetic rate, dark respiration and N and P concentrations were measured in 80 palm species grown in a common garden, and combined with data of 30 palm species growing in their native habitats. Compared to other species from the global leaf economics data, dicotyledonous broad-leaved trees in tropical rainforest or other monocots in the global leaf economics data, palms possessed consistently higher CGEn, achieved by lowered dark respiration and fairly high foliar P concentration. Combined phylogenetic analyses of evolutionary signal and trait evolution revealed convergent evolution towards high CGEn in palms. We conclude that high CGEn is an evolutionary strategy that enables palms to better adapt to shady environments than coexisting dicot tree species, and may convey advantages in competing with them in the tropical forest understory. These findings provide important insights for understanding the evolution and ecology of palms, and for understanding plant shade adaptations of lower rainforest strata. Moreover, given the dominant role of palms in tropical forests, these findings are important for modelling carbon and nutrient cycling in tropical forest ecosystems.
authors.affiliation: Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, China; University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Ren-Yi
authors.initials: RY
authors.lastname: Ma
authors.affiliation: Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, China.
authors.forename: Jiao-Lin
authors.initials: JL
authors.lastname: Zhang
authors.affiliation: School of Forest Resources and Environmental Science, Michigan Technological University, Houghton, Michigan, United States of America.
authors.forename: Molly A
authors.initials: MA
authors.lastname: Cavaleri
authors.affiliation: Forest Ecology and Forest Management Group, Wageningen University, Wageningen, the Netherlands.
authors.forename: Frank
authors.initials: F
authors.lastname: Sterck
authors.affiliation: Plant Ecophysiology and Evolution Group, State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, and College of Forestry, Guangxi University, Nanning, Guangxi, China.
authors.forename: Joeri S
authors.initials: JS
authors.lastname: Strijk
authors.affiliation: Plant Ecophysiology and Evolution Group, State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, and College of Forestry, Guangxi University, Nanning, Guangxi, China.
authors.forename: Kun-Fang
authors.initials: KF
authors.lastname: Cao
mesh_terms: D000222:Adaptation, Physiological; D028023:Arecaceae / Q000502:physiology*; D005075:Biological Evolution; D002244:Carbon / Q000378:metabolism*; D019069:Cell Respiration; D010788:Photosynthesis; D010802:Phylogeny; D018515:Plant Leaves / Q000502:physiology; D019655:Quantitative Trait, Heritable; D013045:Species Specificity
chemical_list: D002244:Carbon