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Performance, genomic rearrangements and signatures of adaptive evolution: lessons from fermentative yeasts.
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  • Roberto Nespolo,
  • Jaiber Solano-Iguaran,
  • Rocio Paleo-Lopez,
  • Julian Quintero-Galvis,
  • Francisco Cubillos,
  • Francisco Bozinovic
Roberto Nespolo
Universidad Austral de Chile
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Jaiber Solano-Iguaran
Universidad Austral de Chile
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Rocio Paleo-Lopez
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Julian Quintero-Galvis
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Francisco Cubillos
Universidad de Santiago de Chile
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Francisco Bozinovic
universidad catolica de chile
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Abstract

The capacity of some yeasts to extract energy from single sugars, generating CO2 and ethanol (=fermentation), even in the presence of oxygen is known as the Crabtree effect. This phenomenon represents an important adaptation as it allowed the utilization of the ecological niche given by modern fruits, an abundant source of food that emerged in the terrestrial environment in the Cretaceous. However, identifying the evolutionary events that triggered fermentative capacity in Crabtree positive species is challenging, as microorganisms do not leave fossil evidence. Thus, key innovations should be inferred based only on traits measured under culture conditions. Here, we reanalyzed data form a common-garden experiment where several proxies of fermentative capacity were recorded in Crabtree positive and negative species, representing yeast’s phylogenetic diversity. In particular, we applied the “lasso-OU” algorithm which detects points of adaptive shifts, provided trait values representing a given performance measure. We tested whether multiple events or a single event explains the actual fermentative capacity of yeasts. According to the lasso-OU procedure, evolutionary changes in the three proxies of fermentative capacity that we considered (i.e., glycerol production, ethanol yield and respiratory quotient) are consistent with a single evolutionary episode (a whole-genomic duplication, WGD), instead of a series of small genomic rearrangements. Thus, the WGD appears as the key event behind the diversification of fermentative yeasts, which by increasing gene dosage and maximized their capacity of energy extraction for exploiting the new ecological niche provided by single sugars.

Peer review status:ACCEPTED

13 Feb 2020Submitted to Ecology and Evolution
15 Feb 2020Assigned to Editor
15 Feb 2020Submission Checks Completed
18 Feb 2020Review(s) Completed, Editorial Evaluation Pending
20 Feb 2020Editorial Decision: Accept