Diversification of the phaseoloid legumes: effects of climate change, range expansion and habit shift.

Honglei Li,Jianhua Li,Zhiduan Chen,Wei Wang,Li Lin,Xinyu Zhu,Xiangyun Zhu

doi:10.3389/fpls.2013.00386

Abstract

Understanding which factors have driven the evolutionary success of a group is a fundamental question in biology. Angiosperms are the most successful group in plants and have radiated and adapted to various habitats. Among angiosperms, legumes are a good example for such successful radiation and adaptation. We here investigated how the interplay of past climate changes, geographical expansion and habit shifts has promoted diversification of the phaseoloid legumes, one of the largest clades in the Leguminosae. Using a comprehensive genus-level phylogeny from three plastid markers, we estimate divergence times, infer habit shifts, test the phylogenetic and temporal diversification heterogeneity, and reconstruct ancestral biogeographical ranges. We found that the phaseoloid lineages underwent twice dramatic accumulation. During the Late Oligocene, at least six woody clades rapidly diverged, perhaps in response to the Late Oligocene warming and aridity, and a result of rapidly exploiting new ecological opportunities in Asia, Africa and Australia. The most speciose lineage is herbaceous and began to rapidly diversify since the Early Miocene, which was likely ascribed to arid climates, along with the expansion of seasonally dry tropical forests in Africa, Asia, and America. The phaseoloid group provides an excellent case supporting the idea that the interplay of ecological opportunities and key innovations drives the evolutionary success.

Highlights

Species diversity of different lineages inhabiting the Earth is strikingly heterogeneous
The most recent common ancestor (MRCA) of Pueraria phaseoloides and Pueraria lobata emerged at ca. 13.4 Ma (HPD: 9.9–17.0 Ma)
Based on our time estimates, the MRCA of Pueraria loata and Pueraria phaseoloides dated back to the Middle Miocene, which coincides with the oldest fruit and foliage fossil records of Pueraria (Wang et al, 2010, and References therein)

Summary

Introduction

Species diversity of different lineages inhabiting the Earth is strikingly heterogeneous. Ecological opportunity and/or key innovation have been considered as a cause of high diversification rates in many groups (e.g., Yoder et al, 2010; Duputié et al, 2011; Claramunt et al, 2012; Erkens et al, 2012). Little is known about how ecological opportunity and key innovation have interplayed to promote diversification of a group. The phaseoloid legumes represent one of the largest clades in Leguminosae and consist of 114 genera with ca. The aforementioned phylogenetic analyses of the clade usually sampled less than 40% of the generic diversity in the group; to understand the evolutionary dynamics responsible for its current diversity we need a well-resolved phylogeny of the phaseoloid genera with more comprehensive taxon sampling

Methods

Results

Conclusion