Phylogenetic structure and formation mechanism of shrub communities in arid and semiarid areas of the Mongolian Plateau.

Ying Zheng,Jinghui Zhang,Zhiyong Li,Lei Dong,Chengzhen Jia,Frank Yonghong Li,Lixin Wang,Zijing Li,Cunzhu Liang,Bailing Miao

doi:10.1002/ece3.5787

Abstract

The mechanisms of species coexistence within a community have always been the focus in ecological research. Community phylogenetic structure reflects the relationship of historical processes, regional environments, and interactions between species, and studying it is imperative to understand the formation and maintenance mechanisms of community composition and biodiversity. We studied the phylogenetic structure of the shrub communities in arid and semiarid areas of the Mongolian Plateau. First, the phylogenetic signals of four plant traits (height, canopy, leaf length, and leaf width) of shrubs and subshrubs were measured to determine the phylogenetic conservation of these traits. Then, the net relatedness index (NRI) of shrub communities was calculated to characterize their phylogenetic structure. Finally, the relationship between the NRI and current climate and paleoclimate (since the Last Glacial Maximum, LGM) factors was analyzed to understand the formation and maintenance mechanisms of these plant communities. We found that desert shrub communities showed a trend toward phylogenetic overdispersion; that is, limiting similarity was predominant in arid and semiarid areas of the Mongolian Plateau despite the phylogenetic structure and formation mechanisms differing across habitats. The typical desert and sandy shrub communities showed a significant phylogenetic overdispersion, while the steppified desert shrub communities showed a weak phylogenetic clustering. It was found that mean winter temperature (i.e., in the driest quarter) was the major factor limiting steppified desert shrub phylogeny distribution. Both cold and drought (despite having opposite consequences) differentiated the typical desert to steppified desert shrub communities. The increase in temperature since the LGM is conducive to the invasion of shrub plants into steppe grassland, and this process may be intensified by global warming.

Highlights

The formation and maintenance mechanisms of community biodiversity have been an interesting theme in ecological research for several decades (Roughgarden, 1983; Tilman, 2004; Yang et al, 2011)
Our results show that the phylogenetic structures of shrub communities in the western Mongolian Plateau demonstrate a general trend toward phylogenetic overdispersion, though differences exist among the three groups corresponding to sandy, steppified desert, and typical desert habitats
Desert shrub and sandy shrub community lineage are dominated by overdispersion, with niche limiting similarity the main mechanism of community composition; shrubs in desert‐steppe and steppe‐desert transition areas are affected by herbaceous plant competition and restricted by low temperature, showing a trend of phylogenetic clustering

Summary

| INTRODUCTION

The formation and maintenance mechanisms of community biodiversity have been an interesting theme in ecological research for several decades (Roughgarden, 1983; Tilman, 2004; Yang et al, 2011). If the phylogenetic relationship between species within a community is closer than that predicted by the null model (i.e., phylogenetic clustering), habitat filtering is more important, since it has served to cluster species with similar niches. Given that the study of phylogenetic structure combines regional environment, interspecific relationships, and geological history processes (Fine & Kembel, 2011), the western Mongolian Plateau constitutes an ideal location for phylogenetic study because of its ancient flora and harsh modern environment. We took plant communities in the western Mongolian plateau as a model, for exploring species coexistence mechanisms and how phylogenetic structure responds to climate change in temperate arid and semiarid areas. We hypothesized that low temperature was more restrictive than drought for construction of shrub communities in temperate arid and semiarid areas, and that shrub communities would become phylogenetically more overdispersed under climate warming. This research will allow better understanding of the underlying mechanisms of community assembly and provide insight on biodiversity and ecosystem stability in arid and semiarid areas under global warming

| MATERIALS AND METHODS

| DISCUSSION

| CONCLUSIONS

Findings

CONFLICT OF INTEREST