Systematics/Phytogeography / Taxonomie/ Section
Beck, James , Windham, Michael , Pryer, Kathleen M. .
Investigating the early stages of polyploid evolution in the star-scaled cloak ferns (Astrolepis).
Polyploidy, or the presence of more than two chromosome sets per nucleus, is a pervasive historical and contemporary feature of plant evolution. Most authors view the majority of angiosperms and up to 95% of the approximately 11,000 species of ferns to be polyploid. Although tremendous advances have been made in our understanding of the phylogenetic scope and genomic consequences of polyploidy, we still know relatively little about the initial stages of polyploid evolution in natural populations. Of particular interest are the adaptive potentials of new polyploid lineages. Do new polyploids occupy the same habitats as their parental species (thus implying immediate competition), or are they projected into novel niches? Do independently derived polyploid lineages occupy different niches? The polyploid fern species Astrolepis integerrima (Pteridaceae) provides a unique opportunity to address these questions. It is an apomictic triploid, the result of hybridization between the diploid species A. crassifolia and A. cochisensis, and has successfully colonized a large area including portions of the southwestern U.S.A. and northern Mexico. Interestingly, recent analyses of chloroplast and nuclear sequence data have unequivocally shown that A. integerrima is the result of several distinct hybridization events, consistent with the considerable morphological variation within the species. This recurrent evolution will allow for an evaluation of niche differentiation between A. integerrima and its parents and between independently derived A. integerrima lineages.
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1 - Duke University, Department of Biology, Box 90338, Durham, NC, 27708, USA
2 - Duke University, Department of Biology, Durham, NC, 27708, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Room 6/Woodward
Date: Tuesday, July 29th, 2008
Time: 8:15 AM