Plasticity of functional traits and optimality of biomass allocation in elevational ecotypes of Arabidopsis halleri grown at different soil nutrient availabilities
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In mountainous areas, plant distribution is constrained by various environmental stresses. Plasticity and constancy in plant functional traits may relate to optimal strategies at respective habitats and to ecotypic differentiation along elevation. Although plant biomass allocation has been extensively studied in relation to adaptation to soil nutrient availability along elevation, its optimality is still poorly understood. We examined soil nutrient availability in the field and conducted growth analysis for two elevational ecotypes of Arabidopsis halleri grown under different nutrient availabilities. We determined plasticity in morphological and physiological traits and evaluated optimal biomass allocation using an optimality model. Our field investigation indicated that soil nitrogen (N) availability increased rather than decreased with increasing elevation. Our growth analysis revealed that lowland ecotype was more plastic in morphological variables and N concentrations, whereas the highland ecotype was more plastic in other physiological variables such as the net assimilation rate (NAR). The leaf mass ratio (LMR) in the lowland ecotype was moderately plastic at the whole range of N availabilities, whereas LMR in the highland ecotype was very plastic at higher N availabilities only. The optimality model indicated that the LMR of the lowland ecotype was nearly optimal throughout the range of studied N availabilities, whereas that of the highland ecotype was suboptimal at low N availability. These results suggest that highland ecotype is adapted only to high N availability, whereas the lowland ecotype is adapted to a relatively wide range of N availabilities as a result of natural selection in their respective habitats. We conclude that an adaptive differentiation has occurred between the two ecotypes and plasticity in the biomass allocation is directly related to its optimization in changing environments.
KeywordsFunctional differentiation Optimal allocation Phenotypic plasticity Root/shoot ratio Relative growth rate Functional traits
We thank Dr. Riichi Oguchi for providing valuable comments. This work was supported by grants from MEXT, Japan (KAKENHI nos. 17H03727, 25291095, 21114009), a research grant from the Mitsui & Co., Ltd. Environment Fund, and CREST (no. JPMJCR11B3), JST, Japan.
KH designed the research, SM, NY and KH conducted fieldwork, QWW, MD, and SN performed experiments and determined variables of samples, QWW analyzed data and performed simulation analysis, and QWW and KH wrote the manuscript.
- Hara H (1936) Arabis gemmifera var. alpicola. J Jpn Bot 12:900–901Google Scholar
- Lavorel S, Gachet S, Sahl A, Gaucherand S, Bonet R (2009) A plant functional traits data base for the Alps: understanding functional effects of changed grassland management. In: Spehn CKE (ed) Georeferenced biological databases as a tool for understanding mountain biodiversity. CRC Press, Boca RatonGoogle Scholar
- Molles MC (2005) Ecology: concepts and applications, 3rd edn. The McGraw-Hill Companies, Inc, New YorkGoogle Scholar
- Valladares F, Balaguer L, Martinez-Ferri E, Perez-Corona E, Manrique E (2002a) Plasticity, instability and canalization: is the phenotypic variation in seedlings of sclerophyll oaks consistent with the environmental unpredictability of Mediterranean ecosystems? New Phytol 156:457–467CrossRefGoogle Scholar
- Valladares F, Chico JM, Aranda I, Balaguer L, Dizengremel P, Manrique E, Dreyer E (2002b) The greater seedling high-light tolerance of Quercus robur over Fagus sylvatica is linked to a greater physiological plasticity. Trees Struct Funct 16:395–403Google Scholar
- Yamamoto H (1985) Geology of the late Paleozoic-Mesozoic sedimentary complex of the Mino Terrane in the southern Neo area, Gifu Prefecture and the Mt. Ibuki area, Shiga Prefecture, central Japan. J Meteorol Soc Jpn 91:353–369Google Scholar