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Slide #1. Gene Flow Structured Populations and Species Cohesion in the Cichlid Fishes of Lake Malawi Slide #2. acknowledgements Slide #3. Slide 3 Slide #4. Slide 4 Slide #5. The Great Lakes of the Rift Valley Slide #6. Extraordinary taxonomic diversity of African great lake Cichlids Slide #7. Why so many species? Slide #8. Phylogeny of African Great Lake Cichlids* Slide #9. African Lake Cichlids are a recurrent topic in Mayr’s arguments on sympatric speciation Slide #10. 1984* – Recognized that speciation had occurred within lakes and that recurrent colonization could not explain the diversity <BR>Argued in favor of speciation facilitated by geographic factors, rather than ecological ones Slide #11. 2001* - Acknowledged that sympatric speciation had probably occurred in crater lake cichlids of Cameroon Slide #12. The Rock Dwellers (Mbuna) of Lake Malawi Slide #13. Strong sexual dimorphism for coloration Slide #14. Color motifs are repeated within and among species and genera Slide #15. Nearly all measured genetic variation is shared by many species Slide #16. Sampling for research on the divergence of Mbuna species Slide #17. maps Slide #18. A population genetic approach to questions on divergence Slide #19. Nielsen, R. & Wakeley, J. (2001) Genetics 158, 885-96 Slide #20. Recent Extensions* Slide #21. The probability distribution of the Slide #22. T – parameters of the IM model <BR> Xj – data for locus j <BR> Gj – genealogy for locus j Slide #23. T – parameters of the IM model <BR> Xj – data for locus j <BR> Gj – genealogy for locus j Slide #24. But …how to quantify divergence parameters when all genetic variation is shared? Slide #25. Compound Loci with two kinds of sequences: unique sequence and linked STR (microsatellite) Slide #26. Adding HapSTR loci to the MCMC method for fitting the Isolation with Migration model Slide #27. Example with three species, one locus: <BR>Sixteen STR alleles were observed <BR>Many Alleles are shared Slide #28. Two polymorphic sites were found in the sequence, with three sequence haplotypes (CC, CT, AT). <BR>Within sequence haplotypes, multiple cases where alleles are shared Slide #29. Tropheops tropheops Slide #30. Tropheops gracilior Slide #31. Tropheops ‘Broad Mouth’ Slide #32. Samples and Data Slide #33. Molecular Clock Dating Slide #34. Divergence time estimates between populations, within species Slide #35. Correspondence Analysis of multilocus (6 loci) STR genotypes Slide #36. Divergence of two populations of T. gracilior Slide #37. Divergence of T. tropheops and T. gracilior Slide #38. Divergence of T. ‘Broad Mouth’ and T. gracilior Slide #39. Divergence of T. ‘Broad Mouth’ and T. tropheops Slide #40. Common Findings 1 Slide #41. Common Findings 2 Slide #42. Common Findings 3 Slide #43. Common Findings 4 Slide #44. Overall Portrait Slide #45. The End