Do asexual polyploid lineages lead short evolutionary lives? A case study from the fern genus Astrolepis.

Journal Article

A life-history transition to asexuality is typically viewed as leading to a heightened extinction risk, and a number of studies have evaluated this claim by examining the relative ages of asexual versus closely related sexual lineages. Surprisingly, a rigorous assessment of the age of an asexual plant lineage has never been published, although asexuality is extraordinarily common among plants. Here, we estimate the ages of sexual diploids and asexual polyploids in the fern genus Astrolepis using a well-supported plastid phylogeny and a relaxed-clock dating approach. The 50 asexual polyploid samples we included were conservatively estimated to comprise 19 distinct lineages, including a variety of auto- and allopolyploid genomic combinations. All were either the same age or younger than the crown group comprising their maternal sexual-diploid parents based simply on their phylogenetic position. Node ages estimated with the relaxed-clock approach indicated that the average maximum age of asexual lineages was 0.4 My, and individual lineages were on average 7 to 47 times younger than the crown- and total-ages of their sexual parents. Although the confounding association between asexuality and polyploidy precludes definite conclusions regarding the effect of asexuality, our results suggest that asexuality limits evolutionary potential in Astrolepis.

Full Text

Duke Authors

Cited Authors

  • Beck, JB; Windham, MD; Pryer, KM

Published Date

  • November 2011

Published In

Volume / Issue

  • 65 / 11

Start / End Page

  • 3217 - 3229

PubMed ID

  • 22023587

Electronic International Standard Serial Number (EISSN)

  • 1558-5646

Digital Object Identifier (DOI)

  • 10.1111/j.1558-5646.2011.01362.x

Language

  • eng

Conference Location

  • United States