@ARTICLE{TreeBASE2Ref19691, author = {James Benjamin Beck and Michael D. Windham and Kathleen M. Pryer}, title = {Do asexual polyploid lineages lead short evolutionary lives? A case-study from the fern genus Astrolepis}, year = {2011}, keywords = {lineage-age, Mexico, phylogeny, plastid DNA, spore}, doi = {}, url = {http://}, pmid = {}, journal = {Evolution}, volume = {}, number = {}, pages = {}, abstract = {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 vs. 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 Mya, 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.} }

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