Movement of DNA from one genomic location to another, or from one genome to another, has been an important process in the structuring of genomes and has manifold consequences. One system that has comprised much of our past research efforts in this area is the study of retrotransposons (Cummings 1992, Cummings 1994, Konieczny et al. 1991, Voytas
et al. 1990, Voytas et al. 1992). I am interested in evolution and distribution of retrotransposons and how their special properties influence their evolutionary patterns. Our past research on these elements focused on a class most similar to the copia elements of Drosophila melanogaster. This research ranged from characterizing these elements in the crucifer Arabidopsis thaliana to a broad phylogenetic survey including nine of ten divisions of plants and several protist groups. One of the more significant results of this research was demonstrating that this class of transposable elements is present in all plant lineages, making it the most widespread group of transposable elements yet characterized.
Another class of transposition events important in evolution involve the movement of genetic material between different sub-cellular genomes; nuclear, chloroplast and mitochondrial. We completed a project using analysis of Southern blot hybridization and DNA sequence data to examine the evolutionary dynamics of transposition events from the plastid genome to the mitochondrial genome in angiosperms (Cummings et al. 2003). Analyses show that interorganelle transposition events have happened repeatedly and independently during angiosperm evolution and that they have involved movement of DNA rather than RNA, which is in contrast to some mitochondrion to nucleus transfers.
Phylogenetic systematics, like population genetics, constitutes one of the principal conceptual frameworks for much of our research and provides the appropriate context for addressing many hypotheses in molecular evolutionary genetics. Additionally, several past projects are explicitly systematic, in whole or in part, in that particular hypotheses regarding relationships are examined. Examples include past research on avocados (Persea spp.; Furnier et al. 1990); grasses (Poaceae; Cummings et al. 1994), flatworms (Platyhelminthes;
Blair et al. 1996, Campos et al. 1998), green algae (Cladophoraspp.; Marks and Cummings 1996), plant pathogens (Phytophthora
spp.; Förster et al. 2000), and horny-head worms (Acanthocephala;
García-Verela et al. 2000, García-Verela et al. 2002). The most recent systematic project focused on the genus Agalinis (Orobanchaceae). The relationships within the genus present several interesting systematic problems and no previous molecular work within the group has been published. Our results both confirmed and refuted several points in the current taxonomy for the genus (Neel and Cummings 2003). We take a very broad view toward systematics, and focus on the implications of the relationships between taxa and what they can tell us about the patterns and processes of evolution.