Baldwin, Bruce G. , Kalisz, Susan , Armbruster, W. Scott .
Diversification and diversity in Collinsia and Tonella (Plantaginaceae).
Diversity in reproductive morphology, genomic arrangements, and ecology of Collinsia has made this annual, North American genus an important subject for studies of mating-system evolution, adaptation, and speciation. Extensive sampling of populations across Collinsia and its putative sister-group, Tonella, was undertaken initially to gain a fine-grained perspective on evolutionary lineages for mating-system analyses and here is examined more broadly in the context of systematics, phytogeography, and diversification. Phylogenetic analyses representing 169 populations of Collinsia and Tonella (and three outgroup genera) were conducted from DNA sequences of nuclear ribosomal transcribed spacers (ITS and ETS), the chloroplast trnK intron, and, for a subset of samples, the single-copy nuclear gene CYCLOIDEA-1. Resultant trees provide a robust set of hypotheses on relationships throughout Collinsia and Tonella, with both genera monophyletic. Our findings demonstrate that diversity in Collinsia has been underrepresented by past taxonomies, with both cryptic and morphologically distinctive lineages. Although most taxa appear to have arisen by divergent evolution, multiple lines of molecular evidence point to a homoploid hybrid origin of C. tinctoria involving lineages represented by C. bartsiifolia/C. corymbosa and C. heterophylla. Phylogenetic evidence indicates that evolutionary divergence in Collinsia often has been associated with shifts in habitat (including distinct climatic and edaphic settings), phenology, and/or floral traits, with shifts in putative mating-system occurring repeatedly throughout the tribe. A chronogram of Collinsia + Tonella indicates that sympatric sister-taxa that differ in floral traits putatively associated with different mating-systems range widely in divergence times, but that divergence of such taxa can occur quickly (e.g., < 0.1 Ma, for varieties of C. sparsiflora). Phylogeographic patterns indicate an origin for Collinsia + Tonella in the NW California Floristic Province (CA-FP), with initial diversification of Collinsia in that region followed by repeated dispersals to the north, east, and south.
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1 - University of California, Berkeley, Jepson Herbarium and Department of Integrative Biology, 1001 Valley Life Sciences Building #2465, Berkeley, CA, 94720-2465, USA
2 - University of Pittsburgh, Department of Biological Sciences, Langley Hall, Pittsburgh, Pennsylvania, 15260, USA
3 - King Henry I. St. University of Portsmouth, School of Biological Sciences, King Henry Bldg, Portsmouth, PO1 2DY, United Kingdom
Presentation Type: Oral Paper:Papers for BSA Sections
Location: Rendezvous A/Snowbird Center
Date: Tuesday, July 28th, 2009
Time: 10:15 AM