Genome-specific histories of divergence and introgression between an allopolyploid unisexual salamander lineage and two ancestral sexual species

Robert D. Denton, Ariadna E. Morales, H. Lisle Gibbs

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Quantifying introgression between sexual species and polyploid lineages traditionally thought to be asexual is an important step in understanding what drives the longevity of putatively asexual groups. Here, we capitalize on three recent innovations— ultraconserved element (UCE) sequencing, bioinformatic techniques for identifying genome-specific variation in polyploids, and model-based methods for evaluating historical gene flow—to measure the extent and tempo of introgression over the evolutionary history of an allopolyploid lineage of all-female salamanders and two ancestral sexual species. Our analyses support a scenario in which the genomes sampled in unisexual salamanders last shared a common ancestor with genomes in their parental species ~3.4 million years ago, followed by a period of divergence between homologous genomes. Recently, secondary introgression has occurred at different times with each sexual species during the last 500,000 years. Sustained introgression of sexual genomes into the unisexual lineage is the defining characteristic of their reproductive mode, but this study provides the first evidence that unisexual genomes have undergone long periods of divergence without introgression. Unlike other sperm-dependent taxa in which introgression is rare, the alternating periods of divergence and introgression between unisexual salamanders and their sexual relatives could explain why these salamanders are among the oldest described unisexual animals.

Original languageEnglish (US)
Pages (from-to)1689-1700
Number of pages12
JournalEvolution
Volume72
Issue number8
DOIs
StatePublished - 2018
Externally publishedYes

Bibliographical note

Funding Information:
We thank L. Blyth, J. David, K. Greenwald, G. Lipps, T. Matson, and R. Muehlheim for providing the tissue samples for this work. We thank J. Diaz and C. Ries for assistance in the laboratory. We acknowledge M. Broe, J. Clevenger, J. Wendel, H. Guanjing, C. Grover, C. Newman, B. Faircloth, and B. Arnold for their technical advice. This work was funded by a National Science Foundation Doctoral Dissertation Improvement Grant (#1600655) awarded to R.D.D. and H.L.G.

Publisher Copyright:
© 2018 The Author(s), 2018 The Society for the Study of Evolution.

Keywords

  • Ambystoma salamanders
  • Introgression
  • Polyploidy
  • Ultraconserved elements
  • Unisexual lineages

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