Robert C. Vrijenhoek

Bob Vrijenhoek’s interest in gene flow and population genetics evolved from work on the ecology, evolution, and conservation of sexually and asexually reproducing fish in northwestern Mexico and the southwestern US. Genetic tools used for assessing historical connectivity among recently fragmented populations of endangered, stream-dwelling, desert fish were easily transferred to studies of geographically distant populations of invertebrate animals inhabiting nutrient-rich “islands” on the seafloor such as hydrothermal vents, cold seeps, wood, and whale falls.

As adults, most benthic marine invertebrates are either anchored to the seafloor or unable to swim (or crawl) great distances. Despite the lack of mobility as adults, many of these animals maintain species distributions that are separated by great distances, strong currents, and even underwater mountain ranges. The Molecular Ecology Group studied the genetic connections among populations such as these, especially those that thrive in environments like hydrothermal vents, hydrocarbon seeps, wood, and whale falls.

The Molecular Ecology Group described how factors—such as geographic distance, topology of the seafloor, and deep-sea currents—affect the stability and dispersal of vent clams, mussels, snails and tubeworms, and they discovered the first mid-ocean hybrid zones. These genetic studies also revealed rapid evolution of the modern vent and seep animals during the Cenozoic era. Worldwide marine expeditions over the past 25 years have resulted in Bob Vrijenhoek and his collaborators discovering and describing many species of crabs, clams, mussels, snails, and annelids that were new to science, including Osedax, the unusual polychaete worms that devour sunken bones and produce “harems” of dwarf males.

Most recently, the research team worked with MBARI engineers and external collaborators to develop and test new methodologies for sampling and identifying marine zooplankton. Highly focused, adaptive, sampling of microscopic zooplankton with remotely operated vehicles (ROVs) and autonomous underwater vehicles (AUVs) are coupled with laboratory-based, high-throughput, DNA sequencing to assess their diversity and how physical and biological processes affect their distributions and diversity.