Ph.D., Princeton University, 1978
Postdoctoral Research: Harvard University
Address: 232B Birge Hall
Department: Botany and Environmental Studies
Research InterestsGene flow in relation to population genetic structure; Causes and consequences of inbreeding.
Research FieldsEvolutionary & Population Genetics
Small and/or inbred populations face many
hazards including the accumulation of deleterious mutations (increasing
the genetic load) and the increased expression of these mutations upon
inbreeding (inbreeding depression). While inbred populations may
eliminate some of their load via selection against deleterious recessive
alleles, such purging is inefficient in small populations for that part
of the load due to mildly deleterious mutations. We are measuring how
quickly and completely purging of the load occurs in experimental
populations of the fast-cycling self-incompatible annual plant, Brassica
rapa. Evaluating how much purging occurs in small inbred populations
helps us understand how selection modifies the evolution of plant
reproductive characters like flower size and selfing rates. It also
helps us understand what genetic threats exist for small and/or isolated
populations such as those maintained under captivity.
We also use isozyme and DNA markers to investigate gene flow and population differentiation in isolated populations of several plants, e.g., wild rice and several tropical tree species. These methods help to identify how genetic variation is distributed and maintained in natural plant populations. We also use markers to infer male and female reproductive success and thus selection on sexual characters in plants.
Steven, J.C. and Waller, D.M. 2004.
Reproductive alternatives to insect pollination in four species of
Thalictrum (Ranunculaceae). Plant Species Biology 19:73-80.
Keller, L. and Waller, D.M. 2002. Inbreeding effects in wild populations. Trends in Ecology and Evolution 17:230-241.
Callahan, H.S. and Waller, D.M. 2000. Phenotypic integration and the plasticity of integration in an amphicarpic annual. International Journal of Plant Sciences 161:89-98.
Byers, D. and Waller, D.M. 1999. Do plant populations purge their genetic load? Effects of population size and mating history on inbreeding depression. Ann. Rev. Ecol. Syst. 30:479-513.
Byers, D., and D.M. Waller. 1999. Do plant populations purge their genetic load? Effects of population size and mating history on inbreeding depression. Ann. Rev. Ecol. and Syst. 30:479-513.