Systematics/Phytogeography / Taxonomie/ Section
Johnson, Leigh A. , Chan, Lauren M. , Burr, Kirsti A. .
Relationships and reticulation among the vernal pool navarretias (Polemoniaceae) revisited: insights from single-copy nuclear gene PISTILLATA sequences.
Hybridization is recognized as an important process in species formation among some genera of the phlox family, whereas cladogenesis is the only process invoked in others. Building on previous work in our lab, we added intron sequences from the nuclear single-copy PISTILLATA gene to clarify patterns of reticulation evident when comparing cpDNA and nrDNA ITS sequences in Navarretia section Navarretia. This group of 10 species (17 taxa) presumably is composed of only diploids that diversified through adaptive evolution as populations fragmented or were isolated following dispersal. Our sampling of multiple populations from geographic disparate localities reveals complex patterns of hybridization and genome merging. Whereas ITS and cpDNA sequences implicate allopolyploidy in a single species, PISTILLATA sequences indicate that allopolyploidy, rather than introgression alone, is the source of discordance for two more species. Three additional species are likely polyploids, or contain at least some polyploid populations. Furthermore, one morphospecies of allopolyploid derivation has at least two independent origins, and primary hybrids between two polyploids have been collected in the field, indicating that hybridization remains a potentially active force for generating diversity in this clade. Combined with comparative morphological study, our results provide insights into problems encountered with species delimitation in this ecologically interesting group of Navarretia.
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1 - Brigham Young University, Department of Biology, 401 Widtsoe Building, Provo, Utah, 84602, USA
2 - Brigham Young University, Department of Biology, 401 Widstoe Building, Provo, Utah, 84602, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Room 5/Woodward
Date: Tuesday, July 29th, 2008
Time: 2:30 PM