Population genomic sequencing of Coccidioides fungi reveals recent hybridization and transposon control

Daniel E. Neafsey, Bridget M. Barker, Thomas J. Sharpton, Jason E. Stajich, Daniel J. Park, Emily Whiston, Chiung Yu Hung, Cody McMahan, Jared White, Sean Sykes, David Heiman, Sarah Young, Qiandong Zeng, Amr Abouelleil, Lynne Aftuck, Daniel Bessette, Adam Brown, Michael FitzGerald, Annie Lui, J. Pendexter MacdonaldMargaret Priest, Marc J. Orbach, John N. Galgiani, Theo N. Kirkland, Garry T. Cole, Bruce W. Birren, Matthew R. Henn, John W. Taylor, Steven D. Rounsley

Research output: Contribution to journalArticlepeer-review

141 Scopus citations


We have sequenced the genomes of 18 isolates of the closely related human pathogenic fungi Coccidioides immitis and Coccidioides posadasii to more clearly elucidate population genomic structure, bringing the total number of sequenced genomes for each species to 10. Our data confirm earlier microsatellite-based findings that these species are genetically differentiated, but our population genomics approach reveals that hybridization and genetic introgression have recently occurred between the two species. The directionality of introgression is primarily from C. posadasii to C. immitis, and we find more than 800 genes exhibiting strong evidence of introgression in one or more sequenced isolates. We performed PCRbased sequencing of one region exhibiting introgression in 40 C. immitis isolates to confirm and better define the extent of gene flow between the species. We find more coding sequence than expected by chance in the introgressed regions, suggesting that natural selection may play a role in the observed genetic exchange. We find notable heterogeneity in repetitive sequence composition among the sequenced genomes and present the first detailed genome-wide profile of a repeat-induced point mutation (RIP) process distinctly different from what has been observed in Neurospora. We identify promiscuous HLA-I and HLA-II epitopes in both proteomes and discuss the possible implications of introgression and population genomic data for public health and vaccine candidate prioritization. This study highlights the importance of population genomic data for detecting subtle but potentially important phenomena such as introgression.

Original languageEnglish (US)
Pages (from-to)938-946
Number of pages9
JournalGenome research
Issue number7
StatePublished - Jul 2010

ASJC Scopus subject areas

  • Genetics
  • Genetics(clinical)


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