1. 1Department of Biology, Indiana University, Bloomington, IN 47405, USA
2. 2Department of Biological Sciences, University of the Sciences in Philadelphia, Philadelphia, PA 19104, USA
3. †Present address: Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
4. 3Center for Genomics and Bioinformatics, Indiana University, Bloomington, IN 47405, USA
5. 4Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA
6. ‡Present address: Department of Biological Sciences, University of Idaho, Moscow, ID 83844, USA.