Affiliations 

  • 1 Department of Organismic and Evolutionary Biology, Harvard University Herbaria, 22 Divinity Avenue, Cambridge, MA, 02138, USA
  • 2 Departamento de Ciências Biológicas, Universidade Estadual de Santa Cruz, Ilhéus, 45.662-900, Bahia, Brazil
  • 3 Rimba Ilmu Botanic Garden, Institute of Biological Sciences, University of Malaya, 50603, Kuala Lumpur, Malaysia
  • 4 Department of Ecology and Evolution, Stony Brook University, Stony Brook, NY, 11794, USA
  • 5 Department of Statistics and Institute of Bioinformatics, University of Georgia, Athens, GA, 30602, USA
New Phytol., 2019 01;221(1):565-576.
PMID: 30030969 DOI: 10.1111/nph.15357

Abstract

Whole-genome duplications (WGDs) are widespread and prevalent in vascular plants and frequently coincide with major episodes of global and climatic upheaval, including the mass extinction at the Cretaceous-Tertiary boundary (c. 65 Ma) and during more recent periods of global aridification in the Miocene (c. 10-5 Ma). Here, we explore WGDs in the diverse flowering plant clade Malpighiales. Using transcriptomes and complete genomes from 42 species, we applied a multipronged phylogenomic pipeline to identify, locate, and determine the age of WGDs in Malpighiales using three means of inference: distributions of synonymous substitutions per synonymous site (Ks ) among paralogs, phylogenomic (gene tree) reconciliation, and a likelihood-based gene-count method. We conservatively identify 22 ancient WGDs, widely distributed across Malpighiales subclades. Importantly, these events are clustered around the Eocene-Paleocene transition (c. 54 Ma), during which time the planet was warmer and wetter than any period in the Cenozoic. These results establish that the Eocene Climatic Optimum likely represents a previously unrecognized period of prolific WGDs in plants, and lends further support to the hypothesis that polyploidization promotes adaptation and enhances plant survival during episodes of global change, especially for tropical organisms like Malpighiales, which have tight thermal tolerances.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.