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Abstract Detail

Population Genetics

Fehlberg, Shannon [1], Ty, Maureen [2], Ferguson, Carolyn [2].

Genetic evidence bolstering the hypothesis of a hybrid origin of Phlox pilosa subsp. deamii (Polemoniaceae).

Hybridization is recognized as an important process in the evolutionary history of plants and can lead to the generation of new species. Hybrid speciation is most commonly accompanied by a change in ploidy level (allopolyploidy), but may also occur at the homoploid level. In order to understand the role of homoploid hybrid origins in plant diversification more completely, additional examples and study systems are needed. Phlox, a genus consisting of ca. 60 species found mostly in North America, is an important subject for evolutionary studies because of its extensive diversification and hybridization. Of particular interest is Phox pilosa subsp. deamii, which is hypothesized to have arisen from hybridization between P. pilosa subsp. pilosa and P. amoena on the basis of past morphological, protein profile, and phylogenetic studies. In the present study, we used a combination of microsatellite data and chloroplast DNA sequence data to address the following questions: What are the patterns of genetic diversity and distance within and among populations of P. pilosa subsp. deamii and its putative parental taxa? Is there evidence for a homoploid hybrid origin for this taxon? A total of 144 individuals (five to seven populations for each taxon, eight individuals each) were sampled from Alabama, Kentucky, Illinois, Indiana, and Tennessee. All individuals were genotyped at five microsatellite loci, and sequences were obtained for a subset of individuals for three chloroplast regions. Data were analyzed using standard diversity and distance analyses, multivariate analysis (principle coordinates), and Bayesian clustering analysis (Structure). These analyses revealed that populations of each taxon harbor high levels of genetic diversity and are well differentiated, both within and among taxa. Ordination and hybrid index analyses suggest that diversity in P. pilosa subsp. deamii is generally intermediate between putative parental taxa. Relationships based on cpDNA sequences are consistent with the findings of the population genetic study, and these data are placed within the context of phylogenetic relationships for the genus. Overall, this genetic work strengthens the long-standing hypothesis of a homoploid hybrid origin of P. pilosa ssp. deamii, and has valuable implications for ongoing research on diversification in this study system.

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1 - Desert Botanical Garden, 1201 N. Galvin Pkwy., Phoenix, AZ, 85008, USA
2 - Kansas State University , Herbarium and Division of Biology, Manhattan, KS, 66506, USA

Homoploid hybrid speciation

Presentation Type: Oral Paper:Papers for Topics
Session: 40
Location: Marlborough B/Riverside Hilton
Date: Wednesday, July 31st, 2013
Time: 8:45 AM
Number: 40001
Abstract ID:441
Candidate for Awards:Margaret Menzel Award

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