Porter, J. Mark , LaDoux, Tasha , Friar, Elizabeth A. .
Evolution of Self-incompatibility in Polemoniaceae.
Many types of self-incompatibility (SI) have been described in angiosperms, however the evolutionary relationships among SI types are largely unknown. Previous studies within Polemoniaceae have reported three homostylous SI systems and one heterostylous SI system. In addition, both stigmatic and ovarian pollen tube inhibition has been reported. We evaluate the evolution of self-incompatibility and the correlated traits that compose SI syndromes in Polemoniaceae, using Bayesian phylogenetic inference of an eight gene supermatrix. Crossing experiments and the literature reveal that of the 395 taxa sampled, 49 are SI, while 137 are self-compatible. The evolution of SI was evaluated using maximum likelihood and employed the posterior distribution of trees. Different rates for gain and loss of SI is always preferred over Dollo (irreversible) or a single rate for gain and loss. We find no evidence for concomitant or correlated change among site of pollen tube arrest, single or multiple locus genetic control of the SI response, or sporophytic vs. gametophytic recognition. While likelihood methods reject Dollo evolution of SI in Polemoniaceae, we show that similar analysis of a trait that that is expected evolve according to Dollo’s law, i.e., polyploidy (with a nearly identical frequency of character states), also rejects Dollo evolution. If one of the character states influences diversification, then likelihood-ratio tests may be a biased against Dollo evolution. Even so, employment of the BiSSE model fails to support the Dollo evolution hypothesis for either SI or polyploidy.
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1 - Rancho Santa Ana Botanic Garden, 1500 North College Avenue, Claremont, California, 91711, USA
2 - University of California Riverside, Granite Mtns. Desert Research Center, HC1 Box 101, Kelso, CA, 92351, USA
3 - Rancho Santa Ana Botanic Garden, Botany, Claremont Graduate University, 1500 N. College Ave., Claremont, CA, 91711, USA
Presentation Type: Oral Paper:Papers for Sections
Location: 552B/Convention Center
Date: Wednesday, August 4th, 2010
Time: 10:15 AM