Current projects include:
Genetic and ecological mapping of molecular flowering time polymorphisms
Flowering is a crucial life history transition in plants. We can employ theory from analogous transitions in animals, like metamorphosis and diapause, to understand that flowering is a discrete and costly morphological transition to another stage of the life cycle.
Plants with determinant groth must carefully integrate genetic and environmental signals before committing themselves to flower, so as not to flower too early or too late and be out of synch with favorable environmental conditions or pollinators. To address questions on the evolution of life history transitions and their ecological implications, we are using high-throughput mapping approaches to identify loci that are associated with flowering time variation, and then we are using finer-scale techniques (near-isogenic lines, transgenic insertions) to verify these candidate genomic regions.
We are combining this molecular genetic information with landscape ecology approaches to understand the ecological, evolutionary, and environmental forces shaping the distributions of the functionally important alleles on the landscape. This is analogous to studying the distributions and evolutionary histories of organisms, except at a finer scale (genes rather than whole species).
The effect of herbivory on ecology and development
Herbivory on the reproductive structures has direct life history implications, because plants that lose their investment in reproduction to an herbivore either have to start all over again, at a metabolic cost to the organism and resulting in an altered phenology, or they have to miss out on reproduction for the season (or for their life).
We use population genetic and phylogenetic methods, combined with environmental information, to understand how tolerance evolves. Furthermore, we utilize gene expression arrays and mapping approaches to identify loci that are involved in modulating tolerance responses in Arabidopsis and other plants. We also verify candidate genes, using a combination of approaches, including RT-QPCR, near-isogenic lines, genetic transformations. We use natural populations for this work, and incorporate ecologically relevant environmental variation, to document loci with naturally occurring polymorphisms and with environmentally-specific effects.
The landscape-level ecology of East Texas freshwater mussels
We're not just about plants over here...
Freshwater mussels (Unionidae) have experienced dramatic declines in both
abundance and distribution throughout North America over the last century due, in part, to their extreme sensitivity to pollution and other environmental changes. Understanding the ecological factors controlling their distributions is paramount to mussel species survival and recovery plans.
While it is known that the glochidia (larval) stage of the life cycle in freshwater mussels normally requires a fish host, it is not understood which fish hosts are most important to which mussel species. Furthermore, it is not clear which mussel species are specialist parasites on particular fish species versus which mussel species are pluralist or generalist parasites. We are determining which fish species are most important to a particular mussel species’ life cycle (and, therefore, its distribution) using niche-modeling.
Combined with genetic evidence that specific mussel glochidia are found on particular host fish species, niche modeling adds more evidence that a particular fish species is an important component of the mussel’s survival and recovery plan. Furthermore, the knowledge about specific fish hosts refines predictions of the mussels’ habitats, since the association between the fishes’ habitats and the mussels’ habitats can be factored into the niche models.
(Photo courtesy of Ashley Dunithan.)