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Notes on Modeling marine microbes in the global ocean, a presentation given by M. Follows (07/17/09)

Ecosystem model with self-assembling communities

  • Becking’s hypothesis:

    “Everything is everywhere but the environment selects.”

  • Governing principle for ocean model: combine genetics and physiology with the physical and chemical environment over which fitness and selection occur determining the ecosystem structure and function

  • Populate the model with a large variety of microbes with different physiological properties chosen randomly

  • The large-scale pattern of nutrients avoid the system to shift from one equilibrum to another equilibrium

  • Biodiversity: About 20 phytoplankton types dominate the biomass and there are many types with very low abundance

  • The spatial structure of some synthetic phytoplankton types fit observed phytoplankton types

Applications

Ecology: diversity and community

  • Plateau of diversity falling poleward, due to the large seasonal cycle (Stewart and Levin 1973; Tilman 1977; Falkowski and Oliver 2007)
  • In the subtropics, stable environment, different types but with same efficiency (found also in laboratory studies)
  • High diversity correlated with highly energetic areas (e.g., western boundary currents): “war adapted” phenotypes advected within the warm waters of the Gulf Stream contribute to diversity at mid-latitude as much as “cold adapted” phenottypes.
  • Hot spots off tropical eastern boundary currents and along the equator. Due to upwelling?

Challenges and opportunities

  • Modelling at the cellular and genomic levels