title: Phytoplankton biogeography and community stability in the ocean.
abstract: BACKGROUND
  Despite enormous environmental variability linked to glacial/interglacial climates of the Pleistocene, we have recently shown that marine diatom communities evolved slowly through gradual changes over the past 1.5 million years. Identifying the causes of this ecological stability is key for understanding the mechanisms that control the tempo and mode of community evolution.
  
  
  RESULTS
  If community assembly were controlled by local environmental selection rather than dispersal, environmental perturbations would change community composition, yet, this could revert once environmental conditions returned to previous-like states. We analyzed phytoplankton community composition across >10(4) km latitudinal transects in the Atlantic Ocean and show that local environmental selection of broadly dispersed species primarily controls community structure. Consistent with these results, three independent fossil records of marine diatoms over the past 250,000 years show cycles of community departure and recovery tightly synchronized with the temporal variations in Earth's climate.
  
  
  CONCLUSIONS
  Changes in habitat conditions dramatically alter community structure, yet, we conclude that the high dispersal of marine planktonic microbes erases the legacy of past environmental conditions, thereby decreasing the tempo of community evolution.
authors.affiliation: Environmental Biophysics and Molecular Ecology Program, Institute of Marine and Coastal Sciences, Rutgers University, New Brunswick, New Jersey, USA. pedro@uvigo.es
authors.forename: Pedro
authors.initials: P
authors.lastname: Cermeño
authors.forename: Colomban
authors.initials: C
authors.lastname: de Vargas
authors.forename: Fátima
authors.initials: F
authors.lastname: Abrantes
authors.forename: Paul G
authors.initials: PG
authors.lastname: Falkowski
mesh_terms: D005075:Biological Evolution; D004463:Ecology; D017753:Ecosystem; D004777:Environment; D005843:Geography; D008386:Marine Biology; D009792:Oceans and Seas; D010839:Phytoplankton / Q000235:genetics*; D011157:Population Dynamics