In addition to conceptual work on the biological bases of homology, variation, and parallel evolution, my research has focused on evolutionary changes in size and shape in mammals: the functional consequences of these changes, and the evolutionary modifications of ontogenetic processes that produce them. This work makes use of DNA sequences, morphometric data, and geographic distributions to study macroevolutionary changes within a phylogenetic context. Projects have included DNA sequence phylogenies of squirrels, experimental work on prenatal maternal effects on body size in large insular deermice, and morphometric studies of growth in elephants, dwarfism in an insular (Pleistocene) dwarf mammoth, and gigantism in insular deermice.