Ecological determinants of mean family age of angiosperm trees in forest communities in China.

Hong Qian,Shengbin Chen

doi:10.1038/srep28662

Abstract

Species assemblage in a local community is determined by the interplay of evolutionary and ecological processes. The Tropical Niche Conservatism hypothesis proposes mechanisms underlying patterns of biodiversity in biological communities along environmental gradients. This hypothesis predicts that, among other things, clades in areas with warm or wet environments are, on average, older than those in areas with cold or dry environments. Focusing on angiosperm trees in forests, this study tested the age-related prediction of the Tropical Niche Conservatism hypothesis. We related the mean family age of angiosperm trees in 57 local forests from across China with 23 current and paleo-environmental variables, which included all major temperature- and precipitation-related variables. Our study shows that the mean family age of angiosperm trees in local forests was positively correlated with temperature and precipitation. This finding is consistent with the age-related prediction of the Tropical Niche Conservatism hypothesis. Approximately 85% of the variance in the mean family age of angiosperm trees was explained by temperature-related variables, and 81% of the variance in the mean family age of angiosperm trees was explained by precipitation-related variables. Climatic conditions at the Last Glacial Maximum did not explain additional variation in mean family age after accounting for current environmental conditions.

Highlights

Species assemblage in a local community is determined by the interplay of evolutionary and ecological processes
Hawkins et al found that in North America forest communities in lower latitudes are dominated by angiosperm trees from older families whereas those in higher latitudes are dominated by angiosperm tress from younger families[6], a finding consistent with the prediction of the Tropical Niche Conservatism hypothesis
Qian found that along a latitudinal gradient in South America, forest communities in warmer latitudes are dominated by angiosperm trees from older families[7], which is consistent with the finding of Hawkins et al.[6] and the prediction of the Tropical Niche Conservatism hypothesis

Summary

Introduction

Species assemblage in a local community is determined by the interplay of evolutionary and ecological processes. Our study shows that the mean family age of angiosperm trees in local forests was positively correlated with temperature and precipitation This finding is consistent with the age-related prediction of the Tropical Niche Conservatism hypothesis. The Tropical Niche Conservatism hypothesis proposes mechanisms underlying patterns of biodiversity and phylogenetic structure in biological communities[5] This hypothesis posits that ecological niches are phylogenetically conserved, most of the land surface of Earth was under tropical climates during the time when many clades (including most of extant angiosperm families) originated, and temperate environments have existed only since the global cooling initiated in the Eocene and is much younger than tropical environments. There is a need to investigate how mean family age is related with climatic variables in other regions of the world

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Results

Conclusion