1. Phylogenetics of Speciation

We use molecular sequencing paired with field studies of reproductive barriers to investigate evolutionary relatonships, biogeographic patterns, and the evolution of pollination syndromes, as well as to conduct taxonimic revision in Malagasy Coleeae and other Old World clades of family Bignoniaceae. Zjhra, Sytsma, and Olmstead 2004.

Graduate Student Andreina Fuentes has recently initiated a project to identify and utilize additional nDNA gene regions for examining patterns and timing of the rapid radiation of species of Coleeae on Madagascar. These additional data sets will allow us to begin to test hypotheses of speciation regarding the effects of biogeography, key innovations, and rates of speciation.

2. Pollinators, Reproductive Barriers & Speciation

Based on extensive fieldwork and molecular sequencing, it is apparent that the evolution of diverse floral forms within Coleeae was influenced by shifts in pollinators.  Pollination in this tribe range from bees to birds to beetles to lemurs. In collaboartion with Dr. James Hutcheon, we are applying the comparative method to tease apart historical constraint from adaptation in the evolution of floral characteristics that correspond to the specialized pollination systems of Coleeae, and to examine the components of floral syndromes. 

Image by Joubert

3. Novel pollinators, Pollination Syndromes & Speciation

We are examining pollination characters of bat-pollinated flowers as potential key aspects of diversification using comparative studies among sympatric species as well as among sister clades. Using a phylogenetic framework, we are examining the constituent features of the bat flower syndrome (flower shape, color, odor, and placement on the tree) and testing these traits on bat perception and preference, in collaboration with bat phylogeneticist, Dr.  J. Hutcheon).

4. Novel Pollination Syndrome, the Role of Floral Odors & Speciation

In collaboration with Dr. R. Raguso, we are investigating the role of floral odors and other floral syndrome components in a suite of early spring flowers of the southeastern U.S. that share a number of pollination traits. We are interested in the traits that attract and provide context for pollinators, the evolutionary patterns of these traits across taxa, and their role in speciation and reversibility in terms of pollination syndromes.

Graduate student Kate Goodrich and undergraduates Courtney Ley and Gordon McFarlan are applying molecular and field approaches to help address these questions. Goodrich, Zjhra and Raguso 2006.

5. Key Innovations, Reproductive Barriers & Speciation

We are exploring cauliflory (placing flowers/fruits on the trunk of a tree) as a potential key adaptation that has evolved repeatedly in lineages within Bignoniaceae. Placing flowers at different heights in tropical forests -potentially partitioned by insect and vertebrate foragers (pollinators and seed dispersers)- may provide the plant with a novel strata niche resulting in reproductive isolation.

We are currently establishing collaborations with developmental biologists to address the underlying control of this trait, as well as continuing our comparative phylogenetic and field studies of this intriguing yet complex tropical phenomena.

Photo by Bryan Brunner

6. Role of Mammals in determining patterns of plant diversity

We are interested in the role mammals play in determining patterns of plant diversity, either due to seed dispersal or megaherbivore impact.

To look at the role of lemurs and other Malagasy mammals on patterns of plant distribution and endemism, we are collaborating with Dr. Beth Kaplin (Antioch New England Graduate School) and Dr. Vololoniaina Jeannoda (University of Antanananarivo, Madagascar).