Phenotypic diversity in natural populations of an endangered plant Tetracentron sinense

Background: Tetracentron sinense, distributed mainly in central and southwest China, is a threatened deciduous broadleaved canopy tree. Presently, little is known about the phenotypic diversity in natural populations of T. sinense, and its fitness and evolutionary potential to the fragmental habitat, which is very important for its conservation. Questions: (1) How is the level of phenotypic diversity in natural populations of T. sinense? (2) Which factors influenced the phenotypic variation? Species study: Tetracentron sinense. Study dates: Between September and October 2014 Methods: 20 phenotypic traits from 11 populations were measured. Nested analysis of variance, multicomparison, principal components analysis, cluster analysis and correlation analysis were used to study the phenotypic variation and its relation to geoclimate factors. Results: Analysis of nested variance showed significant difference among and within populations, but thephenotypic differentiation coefficient and variance component among populations was higher than that within populations. Variation of phenotypic traits in T. sinense was mainly associated with annual sunshine hours, and showed cline variation along longitude and elevation. 11 provenances of T. sinense were clustered into four groups based on PCA. Conclusions: Phenotypic variation in T. sinense mainly existed among population, and there was moderate level of phenotypic differentiation among populations and low level of phenotypic variation within populations in T. sinense. Autogamy or geitonogamy may be the major factor contributing to the low phenotypic variation and moderate genetic divergence within this species. Suggestions for conservation strategies are provided.