Out of Tanganyika: genesis, explosive speciation, key-innovations and phylogeography of the haplochromine cichlid fishes.
BACKGROUND
The adaptive radiations of cichlid fishes in East Africa are well known for their spectacular diversity and their astonishingly fast rates of speciation. About 80% of all 2,500 cichlid species in East Africa, and virtually all cichlid species from Lakes Victoria (approximately 500 species) and Malawi (approximately 1,000 species) are haplochromines. Here, we present the most extensive phylogenetic and phylogeographic analysis so far that includes about 100 species and is based on about 2,000 bp of the mitochondrial DNA.


RESULTS
Our analyses revealed that all haplochromine lineages are ultimately derived from Lake Tanganyika endemics. We find that the three most ancestral lineages of the haplochromines sensu lato are relatively species poor, albeit widely distributed in Africa, whereas a fourth newly defined lineage - the 'modern haplochromines' - contains an unparalleled diversity that makes up more than 7% of the worlds' approximately 25,000 teleost species. The modern haplochromines' ancestor, most likely a riverine generalist, repeatedly gave rise to similar ecomorphs now found in several of the species flocks. Also, the Tanganyikan Tropheini are derived from that riverine ancestor suggesting that they successfully re-colonized Lake Tanganyika and speciated in parallel to an already established cichlid adaptive radiation. In contrast to most other known examples of adaptive radiations, these generalist ancestors were derived from highly diverse and specialized endemics from Lake Tanganyika. A reconstruction of life-history traits revealed that in an ancestral lineage leading to the modern haplochromines the characteristic egg-spots on anal fins of male individuals evolved.


CONCLUSIONS
We conclude that Lake Tanganyika is the geographic and genetic cradle of all haplochromine lineages. In the ancestors of the replicate adaptive radiations of the 'modern haplochromines', behavioral (maternal mouthbrooding), morphological (egg-spots) and sexually selected (color polymorphism) key-innovations arose. These might be - together with the ecological opportunity that the habitat diversity of the large lakes provides - responsible for their evolutionary success and their propensity for explosive speciation.
Salzburger
Walter
W
Lehrstuhl für Zoologie und Evolutionsbiologie, Department of Biology, University of Konstanz, 78467 Konstanz, Germany. walter.salzburger@uni-konstanz.de <walter.salzburger@uni-konstanz.de>
Mack
Tanja
T
Verheyen
Erik
E
Meyer
Axel
A
D000818:Animals; D005075:Biological Evolution; D019070:Cell Lineage; D023681:Cichlids / Q000235:genetics*; D004272:DNA, Mitochondrial / Q000378:metabolism; D019143:Evolution, Molecular; D014644:Genetic Variation; D005843:Geography; D016013:Likelihood Functions; D008954:Models, Biological; D008957:Models, Genetic; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D013045:Species Specificity; D013636:Tanzania
D004272:DNA, Mitochondrial
J Mol Evol. 2003 Jan;56(1):54-68
12569423
Proc Natl Acad Sci U S A. 1998 Jul 21;95(15):8420-7
9671692
Science. 2003 Apr 11;300(5617):325-9
12649486
Trends Ecol Evol. 2004 Apr;19(4):198-207
16701254
Nature. 1990 Oct 11;347(6293):550-3
2215680
Mol Biol Evol. 2003 Jun;20(6):924-30
12716991
Syst Biol. 2002 Feb;51(1):113-35
11943095
Proc Biol Sci. 2000 May 22;267(1447):1049-61
10874756
Science. 1998 Mar 27;279(5359):2115-8
9516114
J Mol Evol. 1995 Jul;41(1):54-66
7608989
Mol Biol Evol. 1994 Jul;11(4):691-703
8078408
Trends Ecol Evol. 2001 Jul 1;16(7):364-371
11403869
Naturwissenschaften. 2004 Jun;91(6):277-90
15241604
Mol Phylogenet Evol. 1995 Dec;4(4):420-32
8747298
Proc Biol Sci. 2003 Jan 22;270(1511):129-37
12590750
Heredity (Edinb). 1998 Jun;80 ( Pt 6):702-14
9675872
Trends Ecol Evol. 1993 Aug;8(8):279-84
21236169
Nature. 1992 Aug 13;358(6387):578-81
1501712
Nat Rev Genet. 2004 Apr;5(4):288-98
15131652
Trends Ecol Evol. 1993 Jun;8(6):197-200
21236147
J Mol Evol. 2004 Jan;58(1):79-96
14743316
Proc Natl Acad Sci U S A. 1997 Jun 24;94(13):6815-9
9192648
Mol Biol Evol. 2002 Jun;19(6):865-83
12032243
Bioinformatics. 2003 Jan 22;19(2):301-2
12538260
Mol Ecol. 2002 Mar;11(3):619-25
11918795
Bioinformatics. 1998;14(9):817-8
9918953
Mol Phylogenet Evol. 1993 Jun;2(2):158-65
8025722
Proc Biol Sci. 2000 Nov 22;267(1459):2273-80
11413643
Mol Ecol. 2001 May;10(5):1075-86
11380867
Mol Biol Evol. 2001 Nov;18(11):2057-66
11606702
Mol Ecol. 2001 May;10(5):1207-25
11380878
Mol Biol Evol. 2002 Jan;19(1):101-9
11752195
Mol Biol Evol. 2001 Feb;18(2):144-54
11158373