Douglas E. & Pamela S. Soltis

Washington State University

Current Research Activities:
Our lab's major research interests are (1) angiosperm phylogeny and character evolution, (2) polyploidy, (3) phylogeny and evolution in Saxifragales, and (4) conservation genetics. Our recent work on reconstructing angiosperm phylogeny has produced a well-resolved and strongly-supported tree (P. Soltis et al., 1999a; D. Soltis et al., 2000). Most significantly, the branching order at the base of the tree is now clear (P. Soltis et al., 2000; Zanis et al., submitted). This resolution allows us to reconstruct the evolutionary history of morphological and biochemical characters across the angiosperms, as we have for numerous characters in the asterids (Albach et al., 2000, in press) and for floral characters in basal angiosperms (Zanis et al., submitted). Our interest in large-scale phylogenetic analyses has led to contributions on data analysis as well (D. Soltis et al., 1998; Mort et al., 2000). Our interest in polyploidy has focused on the genetic and genomic consequences of polyploidy and recurrent polyploid formation (see reviews by D. Soltis and Soltis, 1999; P. Soltis and Soltis, 2000). We have examined both the population-level genetic consequences of polyploidy (e.g., D. Soltis and Soltis, 1989; P. Soltis et al., 1995; Cook et al., 1998) and gene structure and expression in putative "ancient polyploids" (D. Soltis and Soltis, 1990; Pichersky et al., 1990). Ongoing work is examining possible genome rearrangement in polyploids of known ancestry and age in Tragopogon. Phylogenetic analyses of Saxifragales (e.g., Fishbein et al., in press) have clarified relationships and patterns of evolution in this clade that includes large trees, shrubs, and annual and perennial herbs. This phylogenetic framework is being used to explore the evolution of floral form through analyses of ovary position and floral development. This work has demonstrated that ovary position is a more complex character than typically recognized and that simple allometric shifts early in development can result in major morphological changes (Kuzoff et al., 2000). Our work in conservation genetics has explored conceptual issues, such as the role of systematics in conservation biology (Soltis and Gitzendanner, 1999), new molecular and analytical approaches to conservation genetics (Gitzendanner and Soltis, 2000a, 2000b; Gitzendanner et al., submitted), and case studies in which the data will be used in management plans (e.g., Richter et al., 1994; Koontz et al., submitted; Gitzendanner and Soltis, 2000b).

Relationship to the Proposed Project:
We view the proposed RCN as an outstanding opportunity for us to initiate new projects in molecular and genome evolution. Specifically, we are interested in (1) the evolution of genes and gene families across the angiosperms and across the green plants, and (2) the evolution of polyploid genomes and the causes and effects of genome doubling. We have examined the evolution of 18S rDNA in angiosperms (D. Soltis et al., 1997; P. Soltis and Soltis, 1998) and in land plants (P. Soltis et al., 1999b), but interactions with plant genomics researchers through this RCN will allow us to formulate more sophisticated questions and to develop the appropriate methodology to address them. For example, we envision a study where a gene family from Arabidopsis is examined in other angiosperms and perhaps other green plants. How has the structure of the gene family changed? What are the rates and patterns of sequence evolution? What constraints are evident? Have the function and expression patterns changed? Our phylogenetic perspective for the angiosperms and beyond (P. Soltis et al., 1999b) will help us to select appropriate taxa for comparison (cf. D. Soltis and Soltis, 2000). Our proposed collaboration with paleobotanists (RCN proposal, D. Soltis, PI) will help us to provide accurate dates for the divergence points in the angiosperm tree, and this calibration will allow us to compute both relative and absolute rates of molecular evolution. We are also interested in larger-scale genomic changes across evolutionary time, the topic of a pending Biocomplexity Incubation Activity proposal (P. Soltis, PI). We would like to explore both the role of genome doubling in the diversification of angiosperms and all green plants and the patterns and mechanisms of genome evolution following genome doubling. For example, what are the effects of recent and ancient polyploid events on gene evolution and diversification? How rapidly do polyploid genomes rearrange, and are these rearrangements mediated by transposable elements? This RCN would promote interactions between our lab and those of genomic scientists studying the mechanisms and consequences of genome doubling in maize.