1. Species “Species are groups of actually or potentially interbreeding populations, which are reproductively isolated from other such groups” (Mayr, 1942) OEB 192 – 10.09.27

2. Microbial species “…a category that circumscribes a (preferably) genomically coherent group of individual isolates/strains sharing a high degree of similarity in (many) independent features, comparatively tested under highly standardized conditions” (Stackebrandt et al., 2002) “…characterized by a certain degree of phenotypic consistency, showing 70% of DNA-DNA binding and over 97% of 16S ribosomal RNA (rRNA) gene-sequence identity” (Vandamme et al., 1996)

3. Microbial species (Konstantinidis & Tiedje, 2005)

4. Evidence of species?: clusters of microheterogeneity (Acinas et al., 2004)

5. Genome vs. 16S rRNA diversity? (Thompson et al., 2005)

6. How do new species emerge? Allopatric speciation Sympatric speciation

7. “Everything is everywhere – the environment selects.” (Baas-Becking, 1934) Microbial biogeography

8. Ubiquitous dispersal? Diversity of Paraphysomonas (Finlay, 2002) (Finlay & Clarke, 1999)

9. Non-random distributions of free-living taxa (Hughes Martiny et al., 2006)

10. Biogeography: Sulfolobus (Whitaker et al., 2003)

11. Microbes in a host w/ biogeography: Helicobacter pylori (Falush et al.,2003)

12. Ecological species definition? (Cohan, 2001)

13. Case of ecotypes: Prochloroccus (Johnson et al., 2006)

14. Single rule may not always apply (Nesbø et al., 2006)

15. Wednesday (9/29): Microbial speciation