Systematics/Phytogeography / Taxonomie/ Section
Shaw, Joey , Small, Randall .
Concordant phylogeographic patterns of the chloroplast and nuclear genomes in the North American plum syngameon (Prunus subgenus Prunus Section Prunocerasus; Rosaceae).
The North American plums (Prunus subgenus Prunus section Prunocerasus; Rosaceae) are infamous for their very poor development of reproductive isolating barriers. Many North American plum species are interfertile in many combinations and natural hybrids blur nearly all morphologically-based taxonomic boundaries. In previous studies, we showed that the North American plums are monophyletic and that chloroplasts were geographically, rather than taxonomically distributed. Conclusions from our earlier work showed that frequent hybridization has allowed regional sharing of the three primary chloroplast haplotypes among the 17 putative taxa in the section. Here we examined the relationships of the North American plums using intron 1 of the nuclear encoded NADP+ dependent sorbitol-6-phosphate dehydrogenase gene (s6pdh) to test the phylogenetic / phylogeographic conclusions of our earlier studies. Our sampling included multiple accessions of each of the putative species creating a data set parallel to our ealier work. The results showed that most section Prunocerasus taxa are not monophyletic. Although some nuclear haplotypes are more common in some taxa, few are exclusive. Coupled with evidence from our previous studies, these results support the hypothesis that North American plums are an evolutionarily complicated species complex, or syngameon. Another important contribution of this study is to highlight the problem of undersampling in closely related groups of species. However, our results also show that problems can be circumvented by increased sampling.
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1 - University of Tennessee, Chattanooga, Department of Biological and Environmental Sciences, 215 Holt Hall, Department 2653, 615 McCallie Avenue, Chattanooga, Tennessee, 37403, USA
2 - University of Tennessee, Department of Ecology and Evolutionary Biology, 442 Hesler Biology, Knoxville, Tennesee, 37996, USA
Presentation Type: Oral Paper:Papers for Sections
Date: Tuesday, July 29th, 2008
Time: 2:15 PM