Abstract
Physiological, morphological and phenological attributes are potentially adaptive traits that determine functional responses to certain environmental conditions. They are crucial for understanding adaptations to environmental variation along a species natural range. In particular, leaf pigment content can be a good proxy to the physiological and phenological tree state. Our goal was to evaluate the variation in pigment traits among Nothofagus alpina populations in a common garden trail during two years to infer local adaptation and/or phenotypic plasticity. We also aim to analyse the correlation between pigment traits and phenological traits and climatic data from the geographic location of the populations. To comprise the entire range of the species in Argentina, we analysed 400 individuals from eight natural populations coming from four lake watersheds. Pigment traits were estimated using a spectrophotometer and analysed with linear mixed model (LMM). Significant differences among fixed factors (populations - years and watershed – years) were found in chlorophyl a, b, total, carotenoids and anthocyanins concentrations. Higher concentrations were found for 2018, year with the highest number of rainy days and accumulated precipitation. Two populations (Boquete and Tren Tren) were always the most contrasting ones. At population level, the correlation between the means of pigment concentrations and phenological traits was significant in almost all cases. Conversely, the correlation between the means of population pigment concentrations and the main geographic, climatic and bioclimatic variables of the home range were not significant. The significance of the environmental factor (year) in the linear mixed models tested is evidence of phenotypic plasticity of pigment content, suggesting flexibility for acclimatization to moderate inter-annual changes in climatic conditions. The significance of population and watershed and the influence of the family factor on the variance of the pigment traits are evidence of the genetic control as well as the potential adaptive value of leaf pigment content in N. alpina, giving a base for adaptation to a long-lasting change in climate. High correlations between phenological and pigment traits indicate that, in N. alpina, the determination of only one pigment concentration could be used as a proxy of bud burst, senescence and growing degree days.
Phenotypic Plasticity and Genetic Variation of Leaf Pigment Content in a Southern Beech
