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Zygomycetes, microsporidia, and the evolutionary ancestry of sex determination

Tina Koestler1, Ingo Ebersberger

  • 1Center for Integrative Bioinformatics Vienna, University of Vienna, Medical University of Vienna, University of Veterinary Medicine Vienna, Vienna, Austria.

Genome Biology and Evolution
|February 11, 2011
PubMed

Insights

The shared gene cluster in zygomycetes and microsporidia, linked to sex determination, may not be phylogenetically informative. Its presence is likely an ancient trait, suggesting current placement of microsporidia needs reevaluation.

Area of Science:

  • Evolutionary biology
  • Genomics
  • Mycology

Background:

  • Zygomycetes and microsporidia share a unique gene cluster: sugar transporter, high mobility group (HMG)-type transcription factor, and RNA helicase.
  • In zygomycetes, the HMG-type transcription factor is the sole sex determinant, linking this gene cluster's evolution to sex determination evolution.
  • The phylogenetic placement of microsporidia as sister to zygomycetes is based partly on this shared gene cluster.

Purpose of the Study:

  • To investigate the evolutionary relationship between the gene clusters found in zygomycetes and microsporidia.
  • To determine if the shared gene cluster provides phylogenetic information for the placement of microsporidia.
  • To re-evaluate the sister-taxon relationship between microsporidia and zygomycetes.

Main Methods:

  • Comparative analysis of sugar transporter and RNA helicase genes to infer the evolutionary history of the gene cluster.
  • Genome-wide reanalysis of gene order conservation between microsporidia, zygomycetes, other fungi, and humans.

Main Results:

  • If the gene clusters share common ancestry, it dates back to early eukaryotic evolution, potentially making the zygomycete sex determination locus ancient.
  • An alternative hypothesis of independent gene cluster assembly (convergent evolution) is also considered.
  • Gene order conservation is not significantly higher between microsporidia and zygomycetes compared to other fungal taxa or humans.
  • The presence of the gene cluster in both groups is likely a plesiomorphy (ancient shared trait), rendering it phylogenetically uninformative.

Conclusions:

  • The shared gene cluster is not phylogenetically informative for the relationship between microsporidia and zygomycetes.
  • The sister-taxon status of microsporidia to zygomycetes requires reconsideration based on the lack of significant gene order conservation.
  • The evolutionary history of sex determination in fungi and animals may be more complex than previously assumed.

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