Extensive analysis of ORF sequences from two different cichlid species in Lake Victoria provides molecular evidence for a recent radiation event of the Victoria species flock: identity of EST sequences between Haplochromis chilotes and Haplochromis sp. "Redtailsheller".
The Lake Victoria Cichlid fishes have diverged very rapidly. The estimated 500 species inhabiting the lake are believed to have arisen within the last 14,000 years. The fishes' jaws and teeth have diverged markedly to adapt to different feeding behaviors and environments. To examine how the genomes of these fishes differentiated during speciation, we performed comparative analysis of expressed sequenced tag (EST) sequences. We constructed cDNA libraries derived only from the jaw portions of two cichlid species endemic to Lake Victoria. We sequenced 17,280 cDNA clones from Haplochromis chilotes and 9600 cDNA clones from Haplochromis sp. "Redtailsheller" and obtained 543 different genes common to both species. Of these genes, 441 were essentially identical between species and 102 contained base replacements in their open reading frame (ORF) or untranslated (UTR) regions. Comparative analysis of 71 selected sequences has revealed that while the degree of polymorphism is 0.0054/site for H. chilotes and 0.0047/site for H. sp. "Redtailsheller", genetic distance between the two species is 0.0031/site. The genetic distance particularly indicates that the two species diverged about 890,000 years ago.
Watanabe
Masakatsu
M
Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259-B21, Nagatsuta-cho, Midori-ku, Yokohama, 226-8501, Japan.
Kobayashi
Naoki
N
Shin-i
Tadasu
T
Horiike
Tokumasa
T
Tateno
Yoshio
Y
Kohara
Yuji
Y
Okada
Norihiro
N
D000351:Africa, Eastern; D000818:Animals; D005075:Biological Evolution; D023681:Cichlids / Q000145:classification / Q000235:genetics*; D020224:Expressed Sequence Tags; D015723:Gene Library; D005801:Genes, Homeobox; D008445:Maxillofacial Development / Q000235:genetics; D016366:Open Reading Frames; D011110:Polymorphism, Genetic; D017422:Sequence Analysis, DNA