Trajectory and genomic determinants of fungal-pathogen speciation and host adaptation

Proc Natl Acad Sci U S A. 2014 Nov 25;111(47):16796-801. doi: 10.1073/pnas.1412662111. Epub 2014 Nov 3.


Much remains unknown regarding speciation. Host-pathogen interactions are a major driving force for diversification, but the genomic basis for speciation and host shifting remains unclear. The fungal genus Metarhizium contains species ranging from specialists with very narrow host ranges to generalists that attack a wide range of insects. By genomic analyses of seven species, we demonstrated that generalists evolved from specialists via transitional species with intermediate host ranges and that this shift paralleled insect evolution. We found that specialization was associated with retention of sexuality and rapid evolution of existing protein sequences whereas generalization was associated with protein-family expansion, loss of genome-defense mechanisms, genome restructuring, horizontal gene transfer, and positive selection that accelerated after reinforcement of reproductive isolation. These results advance understanding of speciation and genomic signatures that underlie pathogen adaptation to hosts.

Keywords: Metarhizium; genomic features; host specificity; speciation; transitional species.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adaptation, Physiological*
  • DNA Transposable Elements
  • Genomics*
  • Host-Pathogen Interactions*
  • Metarhizium / classification*
  • Metarhizium / genetics
  • Molecular Sequence Data
  • Phylogeny


  • DNA Transposable Elements

Associated data

  • GENBANK/ADNI00000000
  • GENBANK/ADNJ02000000
  • GENBANK/AZHE00000000
  • GENBANK/AZNE00000000
  • GENBANK/AZNF00000000
  • GENBANK/AZNG00000000
  • GENBANK/AZNH00000000