Current Research Projects

  1. Population genetics of local species of crayfish in the genus Orconectes.
  2. Spontaneous mutations affecting fitness in Arabidopsis thaliana.
  3. unPAK: Undergraduates Phenotyping Arabidopsis thaliana knockouts.

Publications

Detailed project descriptions

Sanborn's crayfish

1. Population genetics of local species of crayfish in the genus Orconectes.

My research on the population genetics of crayfish species began with the work described in Kahrl et al. (2014), performing paternity analysis in two species. Our success in this first exploration into the mating systems of crayfish allowed us to pursue further work, demonstrating hybridization between an invasive species and a local species -- an uncommon event in crayfishes.

Though hybridization is generally considered rare, we have reason to believe that the recent biogeographic history of these taxa increases the likelihood of hybridization among close relatives. We are interested in the effects of range contraction and expansion on the integrity of species boundaries and the distribution of genetic variation within and among species. The Central Highlands of the U.S. (which includes Ohio) were recently glaciated; thus, the crayfish living here now must have been displaced south when the glaciers advanced. During that time, close relatives may have been in contact and able to interbreed. These taxa would have expanded north again when the glaciers receded (about 13,000 years ago) but due to recent history, may have retained the capacity for gene flow -- should they meet again. Thus, when the invasive species arrived in local rivers, hybridization is possible.

The immediate trajectory of this project is two-pronged: 1) identifying factors contributing to the ability of these species to hybridize and 2) evaluating the current and potential future consequences of continued hybridization.

2. Spontaneous mutations affecting fitness in Arabidopsis thaliana.

My second research trajectory follows from my graduate work, seeking greater understanding of the ultimate source of new genetic variation: spontaneous mutation. Mutation is both a creative and destructive force in evolution as a new mutation may either improve an individual's survival and reproduction or reduce it. In addition to being the raw material of evolution, studies of spontaneous mutation have the potential to improve our understanding of human health and disease, particularly with respect to the dynamics of cancer (which is frequently caused by new spontaneous mutations arising within an individual).

In graduate school, my work began to explore the effect of environmental conditions on the effects of spontaneous mutations for fitness in plants. My work (with colleagues) demonstrated that mutational effects are often conditional (Rutter et al. 2012, Roles and Conner 2008), in contrast to work carried out in the laboratory. We also corroborated an interesting result first found in the lab: in our study system (Arabidopsis thaliana), up to half of new mutations may be beneficial for plant fitness rather than harmful! This result remains unexplained and is the subject of my current work - I am testing the hypothesis that somatic selection may bias the observed distribution of mutational effects on fitness.

3. unPAK: Undergraduates Phenotyping Arabidopsis thaliana knockouts.

The unPAK project is a multi-institutional collaboration focused on hands-on research experiences for undergraduates. We use a distributed research model in which groups at each participating institution follow a single set of procedures to phenotype Arabidopsis thaliana single-gene knockout mutants (SALK lines) for plant performance traits. There are thousands of SALK T-DNA lines with little or no information on plant phenotype currently available. In our standard experiments, we plant seeds from 11 phytometers (control genotypes) and 122 single-insert mutant genotypes, following the common protocols. In addition, institutions pursue individual projects exploring the effects of other factors on mutant phenotypes. Examples include studies of the impact of increased soil salinity or nutrient stress.

Updated August 2016
by Angela Roles