Director of Research, California Academy of Sciences
Golden Gate Park, San Francisco, CA
Understanding the evolutionary relationships and distribution patterns of organisms is fundamental to most systematic research. My primary interest is the evolutionary history of gastropod mollusks, particularly the Opisthobranchia (nudibranchs and other sea slugs). Snails have independently evolved into slugs on numerous occasions. With the loss of the shell, the gill cavity and internal organs shift position, the nervous system becomes more concentrated, and the hermaphroditic (both male and female organs in a single individual) reproductive ducts become divided and more specialized. These changes have also occurred independently in various lineages of opisthobranchs. This parallel evolution makes opisthobranchs particularly interesting and problematic to modern techniques for determining the sequence of evolutionary change and has broad implications to phylogenetic methodology in general.
During their evolution, opisthobranchs have developed a wide range of toxic and noxious chemicals, largely derived from their prey. Toxicity provides effective protection from predators and has permitted this group of snails to discard their shells. Many opisthobranchs are brightly colored, warning visual predators of the toxicity. This aposematic coloration also involves elaborate patterns, that are shared among members of mimetic complexes, consisting of other groups of snails, flatworms, and sea cucumbers. Coloration related to toxicity has played a major part in the adaptive radiation and diversification of opisthobranchs.
Most opisthobranchs have a shelled larva capable of dispersing over large distances. Many opisthobranchs are therefore distributed widely within the world's oceans. The study of these patterns of biogeography is essential to the understanding of evolution of opisthobranchs.
My field studies have taken me to southern Africa, the western Indian Ocean, Papua New Guinea, the Philippines, and Hawaii. I have also collected extensively in the Caribbean, the Azores, Gough Island and Tristan da Cunha, Baja California, the Galapagos, and the Atlantic and Pacific United States.
A.B. University of California, Berkeley (1972);
M.S. University of Hawaii (1973);
Ph.D. University of New Hampshire (1978).
Lecturer, University of New Hampshire (1978-79).
Curator of Molluscs, South African Museum (1979-82).
Post Doctoral Fellow, Smithsonian Institution (1983-84).
Assistant Curator, California Academy of Sciences (1982-1985);
Associate Curator (1985-1990);
Senior Curator (1990- ).
Fellow, California Academy of Sciences, Hennig Society.
Research Associate, Smithsonian Institution.
President, Western Society of Malacologists (1985).
President, California Malacozoological Society (1987-1996); Vice-President (1996- ).
Councillor, American Malacological Union.
Member, Society of Systematic Zoology, American Society of Zoologists.