Understanding plant evolution, or evolution in general, requires research in a diversity of disciplines.  Research in the Baum lab spans many of these approaches.  The philosophy is to support individuals from diverse disciplinary backgrounds so they can learn from each other while pursuing personally fulfilling research programs.  Below is a summary of some of the ongoing research, organized by discipline.

1) Systematics

We have had a long-standing interest in the phylogeny of Malvaceae s.l., and especially the Malvatheca clade, which includes the traditional families Bombacaceae and Malvaceae. Within this group current work is focused on the phylogeny of the Malagasy Hibisceae (see Maggie’s page); the Matisieae clade, and Bombacoideae.  We are also trying to understand the possible causes ad consequences of a massive increase in the rate of molecular evolution (estimated at as much as nine-fold) that occurred somewhere near the base of Malvoideae.

A second emerging theme is the use of molecular markers to study “species” maintenance.  Two students are currently using nuclear gene genealogies to explore these phenomena.  Maggie Koopman (link to page) is studying species maintenance in the face of documented hybridization among three sympatric, Malagasy species of Megistostegium (Malvaceae/Malvoideae/Hibisceae).  Ivalu Cacho (link to page) is studying geographic patterns of genetic variation within Euphorbia tithymaloides, which forms a possible ring species around the Caribbean basin.

In collaboration with Statistics colleagues, Cecile Ané and Bret Larget , David Baum and former student Stacey Dewitt Smith have developed Bayesian concordance analysis, a new method for using multilocus sequence data to quantify genealogical discordance within genomes and to estimate the proportion of the genome for which a given clade is true (link to: http://www.stat.wisc.edu/~larget/bucky.html). Also in the area of theory, David Baum continues to work on the concepts of species, homology, and phylogenetic nomenclature.

2) Evo-Devo: Evolutionary Developmental Genetics

The Baum lab has endeavored to develop a number of experimental systems in which one can study the genetic basis of morphological evolution above the species level.  A number of projects started in the lab are now continuing elsewhere: TCP genes and the evolution of stamen number evolution in wild relatives of Antirrhinum (Lena Hileman: link: http://www.people.ku.edu/%7Elhileman/); MADS-box floral homeotic genes and the evolution of dioecy in Thalictrum (Vernonica Di Stilio: link http://protist.biology.washington.edu/bio2/people/bio.html?parecID=514); anthocyanin pathway genes and the evolution of flower color in Sinningia (Mathieu Perret) and Iochroma (Stacey Dewitt Smith).  Research is continuing in the following three areas.

Talline Martins  is studying the molecular basis of variation in the presence and position of petal spots in Clarkia gracilis.  This involves studies of petal development, molecular evolution of genes in the anthocyanin pathway, secondary biochemistry, and studies of gene expression.

Ivalu Cacho  and collaborators Gerhard Prenner and Paula Rudall (RBG Kew) are studying the patterns of gene expression in Euphorbia cyathia in an effort to clarify the evolutionary origin of this unusual pseudanthial structure.

Kevin Miller, Raul Correa and a soon to arrive post-doc are using mainly transgenic experiments to try and understand why the flowering architecture of Leavenworthia (Brassicaceae) is so different from typical Brassicaceae species, as illustrated by Arabidopsis thaliana. This work is an extension of previous work on inflorescence architecture in Leavenworthia and other “rosette flowering” Brassicaceae (Shu et al. 2000; Yoon and Baum 2004; Baum et al. 2005; Sliwinski et al. 2006; 2007; Bosch et al. In review).

3) Transgenomics

A new approach being explored in the laboratory, primarily by Raul Correa (link), is transgenomics.  The basic strategy is to isolate large random fragments of genomic DNA from a donor species and introduce them into a recipient species (in our case A. thaliana) by transformation.  The resultant transgenic lines will then be screened for phenotypes of interest: interesting developmental defects and/or traits that resemble the donor species.  We are also interested in genomic fragments from the donor species that cause dominant lethality or sterility in the recipient species, because such genomic fragments may provide information on the kind of genetic mechanisms that underlie postzygotic reproductive isolation.  Raul has developed a high-throughput clone-by-clone strategy for screening 20-25 Kb inserts in a 96-well format.