Beyond the Whole-Genome Duplication: Phylogenetic Evidence for an Ancient Interspecies Hybridization in the Baker's Yeast Lineage.

Marina Marcet-Houben,Toni Gabaldón,Laurence D Hurst

doi:10.1371/journal.pbio.1002220

Abstract

Whole-genome duplications have shaped the genomes of several vertebrate, plant, and fungal lineages. Earlier studies have focused on establishing when these events occurred and on elucidating their functional and evolutionary consequences, but we still lack sufficient understanding of how genome duplications first originated. We used phylogenomics to study the ancient genome duplication occurred in the yeast Saccharomyces cerevisiae lineage and found compelling evidence for the existence of a contemporaneous interspecies hybridization. We propose that the genome doubling was a direct consequence of this hybridization and that it served to provide stability to the recently formed allopolyploid. This scenario provides a mechanism for the origin of this ancient duplication and the lineage that originated from it and brings a new perspective to the interpretation of the origin and consequences of whole-genome duplications.

Highlights

Ancient whole-genome duplications (WGDs) are major evolutionary events that have impacted several eukaryotic lineages, including plants, animals, and fungi [1]
Ancestral WGDs have been identified in monocots and core eudicots [2], and more recent events are apparent in many lineages such as Arabidopsis, maize, and soybean [3,4,5]
To assess whether this peak was related to the WGD event, we limited our analysis to those duplications leading to conserved pairs of WGD-ohnologs as defined in the Yeast Gene Order Browser (YGOB) database [25]

Summary

Introduction

Ancient whole-genome duplications (WGDs) are major evolutionary events that have impacted several eukaryotic lineages, including plants, animals, and fungi [1]. Based on the high level of synteny found between reconstructed ancestrally duplicated gene blocks, it has been proposed that the yeast WGD has its origin in an autopolyploidization event [11]. This proposition has important implications with respect to the possible initial selective advantages that played a role after the polyploidization event. Polyploidy has been considered to promote evolutionary innovation because it facilitates neo- and subfunctionalization and buffers deleterious mutations These mechanisms only provide an advantage after some time has passed and a number of mutations have accumulated. The nature of the initial evolutionary advantage of the yeast WGD remains an open question

Methods

Results

Conclusion