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Robert May ecologist

Robert May ecologist. We have a catalog of all the celestial bodies our instruments can detect in the universe, but …. Photo: Hubble Telescope. … we ignore how many living beings share the Earth with us. Census of Marine Life. The known, the unknown and the knowable.

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Robert May ecologist

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  1. Robert May ecologist

  2. We have a catalog of all the celestial bodies our instruments can detect in the universe, but … Photo: Hubble Telescope

  3. … we ignore how many living beings share the Earth with us

  4. Census of Marine Life The known, the unknown and the knowable O’Dor & Gallardo 2005 Scientia Marina (modified from Falkowski & de Vargas 2004)

  5. www.icm.csic.es/scimar O’Dor & Gallardo Yarincick & O’Dor 2005 Scientia Marina 69 (Suppl 1)

  6. The known: about 6000 species of prokaryotes about 80000 species of protists What is the unknown? How many “taxons” of microbes are there?

  7. How much room for unknown taxons is there? Numbers 2. Niches

  8. 1 cm3 105 prokaryotic cells

  9. 1 dm3 108 prokaryotic cells Most clone libraries

  10. Yungas Nothofagus forest

  11. 1 m3 1011 prokaryotic cells Venter’s study of Sargasso Sea

  12. Equivalent to 2 x 106 km2 of trees

  13. 1.4 x 109 km3 1029 prokaryotic cells The whole ocean

  14. 1st Postulate: The number of microbial cells is enormous

  15. Morse et al.: Nature More niches as size decreases due to fractal structure of nature

  16. H2S SO4 e- CO2 OM Purple sulfur bacteria Lake Cisó (Girona)

  17. Purple sulfur bacteria: Usually several species coexist in nature

  18. Growth rate (h-1)

  19. Percent of cells

  20. Dark Light

  21. 2nd Postulate The number of potential niches is very large

  22. How many taxons of bacteria are there in the sea? Only afew thousand Hagström et al. Appl. Env.Microbiol. 68, 3628–3633 (2002). Perhapstwo million Curtis et al. Proc. Natl Acad. Sci. USA 99, 10494–10499 (2002).

  23. The species difference between related communities suggests that the number of species of bacteria may be more than a THOUSAND MILLION. … speciation in bacteria is easy and extinction difficult, … giving a rate of speciation higher than the rate of extinction, … leading to an ever increasing number of species over time.

  24. AND COROLLARY (FICTION?) … global species number is relatively low FACT The abundance of individuals in microbial species is so large that dispersal is rarely (if ever) restricted by geographical barriers

  25. Science (2005) 310: 1878

  26. 3th Postulate: The number of microbial taxons is VERY large Range: 103 to 106 (perhaps even 109) taxons

  27. T.L. Erwin 1991 ecologist Determining the number of species today is like reaching for the stars; there is no way with the data available today that we are even going to get reasonably close Photo: National Geographic

  28. Ramon Margalef ecologist Biodiversity vs diversity Ramon Margalef (1997) Our Biosphere, Excellence in Ecology Series 10 Biodiversity is the dictionary Diversity is the words used in a book

  29. Biodiversity = Diversity + “Seed bank” Individuals Diversity “Seed bank” Taxon number

  30. Two kinds of taxons

  31. Diversity Seed bank Molecular techniques Culture techniques Individuals Taxon number

  32. Biodiversity = Diversity (Knowable) + “Unknowable” Individuals Diversity Difficult to know Taxon number

  33. Diversity Seed bank BIODIVERSITY

  34. How much room for species is there? Numbers 2. Niches

  35. All the marine bacterioplankton-derived 16S ribosomal DNA sequences … were analyzed When … dereplicated by using 97% similarity as a cutoff, 1117 unique ribotypes were found. We conclude that the apparent bacterioplankton species richness is relatively low.

  36. Analysis of many clones from 10 sampling sites … dominant ribotypes were few (5 in average) and they were often already retrieved in previous analysis In contrast, a large part of each library was new or never found in previous studies… majority of rare ribotypes were specific to each location (I.e. endemic) ..surprisingly low global diversity (around 2000 ribotypes)

  37. T. Pommier, B. Canbäck, K. Hagman, L. Riemann, K. Simu, A. Tunlid & Å. Hagström (in preparation)

  38. How much room for species is there? Numbers 2. Niches

  39. It is sufficient to estimate the area under the species-area curve for a given environment Number of spp can be calculated from the total number of individuals and the abundance of the most abundant members On a small scale: Oceans 160 per mL Soils 6400-38000 per g On a large scale: Whole Oceans 2 x 106 1 Tm Soils 4 x 106

  40. Science (2005) 310: 502

  41. Data from Rosenzweig et al. (1994) Genetics 137:903 Redrawn by Dykhuizen (1998) Ant. Van Leuuwen. 73:25

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