Molecular Ecology

Robert C. Vrijenhoek, Principal Investigator

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.

Giant tubeworms such these as have evolved to live at the boundary between oxygen-poor vent fluids and oxygen-rich seawater. If past catastrophic global environmental changes caused the deep seawater to become oxygen-poor, these worms would have had to adapt, evolve, or die off and be replaced by other animals. ©2003 MBARI

Giant tubeworms such these as have evolved to live at the boundary between oxygen-poor vent fluids and oxygen-rich seawater. ©2003 MBARI

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.

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.

Molecular systematics

Worldwide expeditions led by Bob Vrijenhoek and his colleagues have resulted in the discovery of many new species of deep-sea crabs, clams, mussels, snails, tubeworms and bacteria. Understanding the evolutionary relationships among deep-sea species and placing them in the tree-of-life has been a major goal of research efforts.

Sampling and identifying marine zooplankton

Sampling and identifying marine zooplankton (SIMZ) is a project aimed at advancing our understanding of plankton ecology. SIMZ uses autonomous underwater vehicles (AUVs) to collect samples of zooplankton and molecular genetic techniques to assess their diversity and abundance.

Bone-eating worms

In 2002, MBARI scientists first observed two very odd species of worms living on the bones of a gray whale. Their trunks and brilliant red plumes produced a flowing "shag" carpets that covered many of the bones. The genus Osedax (Latin for bone eater) was formally described in 2004.

Gene flow and dispersal

Analyses of DNA sequences from nuclear and mitochondrial genes have allowed us to reconstruct the recent demographic history of species. Rates of gene flow, geographical patterns of differentiation, and interspecific hybridization have been documented now for a number of deep-sea animals that live at vents and seeps.




Upper-ocean systems
Acoustical ocean ecology
Acoustic instruments
Acoustic fingerprinting
Acoustic community ecology
Acoustics in the news
Biological oceanography
Global modes of sea surface temperature
Krill hotspots in the California Current
Nitrate supply estimates in upwelling systems
Chemical sensors
Chemical data
Land/Ocean Biogeochemical Observatory in Elkhorn Slough
Listing of floats
SOCCOM float visualization
Periodic table of elements in the ocean
Biogeochemical-Argo Report
Profiling float
Interdisciplinary field experiments
Ecogenomic Sensing
Genomic sensors
Field experiments
Harmful algal blooms (HABs)
Water quality
Environmental Sample Processor (ESP)
ESP Web Portal
In the news
Ocean observing system
Midwater research
Midwater ecology
Deep-sea squids and octopuses
Food web dynamics
Midwater time series
Respiration studies
Zooplankton biodiversity
Seafloor processes
Revealing the secrets of Sur Ridge
Exploring Sur Ridge’s coral gardens
Life at Sur Ridge
Mapping Sur Ridge
Biology and ecology
Effects of humans
Ocean acidification, warming, deoxygenation
Lost shipping container study
Effects of upwelling
Faunal patterns
Previous research
Technology development
High-CO2 / low-pH ocean
Benthic respirometer system
Climate change in extreme environments
Station M: A long-term observatory on the abyssal seafloor
Station M long-term time series
Monitoring instrumentation suite
Sargasso Sea research
Antarctic research
Geological changes
Arctic Shelf Edge
Continental Margins and Canyon Dynamics
Coordinated Canyon Experiment
CCE instruments
CCE repeat mapping data
Monterey Canyon: A Grand Canyon beneath the waves
Submarine volcanoes
Mid-ocean ridges
Magmatic processes
Volcanic processes
Explosive eruptions
Hydrothermal systems
Back arc spreading ridges
Near-ridge seamounts
Continental margin seamounts
Non-hot-spot linear chains
Eclectic seamounts topics
Margin processes
Hydrates and seeps
California borderland
Hot spot research
Hot-spot plumes
Magmatic processes
Volcanic processes
Explosive eruptions
Volcanic hazards
Hydrothermal systems
Flexural arch
Coral reefs
ReefGrow software
Eclectic topics
Submarine volcanism cruises
Volcanoes resources
Areas of study
Bioluminescence: Living light in the deep sea
Microscopic biology research
Open ocean biology research
Seafloor biology research
Automated chemical sensors
Methane in the seafloor
Volcanoes and seamounts
Hydrothermal vents
Methane in the seafloor
Submarine canyons
Earthquakes and landslides
Ocean acidification
Physical oceanography and climate change
Ocean circulation and algal blooms
Ocean cycles and climate change
Past research
Molecular ecology
Molecular systematics
SIMZ Project
Bone-eating worms
Gene flow and dispersal
Molecular-ecology expeditions
Ocean chemistry of greenhouse gases
Emerging science of a high CO2/low pH ocean
Maas, Paula A.Y., O'Mullan, Gregory D., Lutz, Richard A., Vrijenhoek, Robert C., (1999). Genetic and morphometric characterization of mussels (Bivalvia: Mytilidae) from Mid-Atlantic hydrothermal vents. Biological Bulletin, 196: 265-272.
Peek, Andrew S., Gaut, Brandon S., Feldman, Robert A., Barry, James P., Kochevar, Randall E., Lutz, Richard A., Vrijenhoek, Robert C., (2000). Neutral and nonneutral mitochondrial genetic variation in deep sea clams from the family Vesicomyidae. Journal of Molecular Evolution, 50: 141-153.
O'Mullan, G.D., P.A.Y. Maas, R.A. Lutz, R.C. Vrijenhoek, (2001). A hybrid zone between hydrothermal vent mussels (Bivalvia: Mytilidae) from the Mid-Atlantic Ridge. Molecular Ecology, 10: 2819–2831.
Full publications list