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The Tilapiini is a tribe within the family Cichlidae commonly known as tilapiine cichlids. Most of the taxa herein are called "tilapias", a diverse and economically important group containing the genera ''Oreochromis'', ''Sarotherodon'' and ''Tilapia''. A number of smaller genera, such as ''Alcolapia'', ''Danakilia'', ''Iranocichla'' and ''Steatocranus'' are also placed herein. They are nowadays placed in the subfamily Pseudocrenilabrinae of African and Middle Eastern cichlids; formerly these were often regarded as a distinct subfamily Tilapiinae. ==Systematics== The tilapiines were recognised by the ichthyologist Ethylwynn Trewavas. () Recent DNA sequence analyses, however, suggest that the Tilapiini as presently delimited are not monophyletic. mtDNA studies〔Nagl ''et al.'' (2001), Klett & Meyer (2002)〕 found that ''Tilapia'', in which formerly all tilapias were united, still seems to constitute a paraphyletic assemblage, composed of a basal grade, ''T. bemini'' which seems closer to haplochromines, and a group containing for example ''T. buttikoferi'' and ''T. ruweti'' of presently unresolved relationships. The first group as well as ''Iranocichla'', ''Oreochromis'', ''Sarotherodon'' and ''Tristramella'' are fairly close to tribes such as the Lamprologini and Tropheini. Unfortunately, the type species of ''Tilapia'' (and hence, the tilapiines) does not seem to be among them. mtDNA-based phylogenies of tilapiines must be evaluated with caution however, as they are usually close to but do ''not'' represent the true evolutionary relationships of these fishes. The reason is that hybridization within any one of these major lineages is known to usually produce fertile offspring, and might also do so between the lineages. Gene pools in these fishes have been kept (largely) separate by behavioral cues since millions of years, but reproductive incompatibility has been far slower to evolve, like in many Pseudocrenilabrinae (African cichlids).〔Nagl ''et al.'' (2001)〕 A small sample size—one to a mere handful of specimens per taxon—as is often used in molecular studies further acerbates the problem. As discussed below for the example of mouthbreeding, non-molecular data such as morphology or behavior has also turned out to be extremely prone to homoplasies, not the least due to the small but ongoing gene flow between evolutionarily quite distant gene pools. Essentially, most traditional and mtDNA-based phylogenetic hypothesis for tilapiines must be considered with a high degree of caution. This problem could be alleviated to some extent by using nDNA sequences. Comparing these with the mtDNA data, hybridization effects could be discerned. Also, it is likely that resolution of nDNA is still good enough to delimit the clades that apparently exist in the "tilapiines" if numerous taxa and specimens are sampled. Researchers could then reanalyze morphological data to discover actual autapomorphies. Evolution seems to run quickly in this group. Even the fast-evolving mtDNA sequences often are incapable of properly resolving interspecies relationships.〔Compare support values and proposed relationships in Nagl ''et al.'' (2001) to Klett & Meyer (2002)〕 It may be that the precise evolutionary history of some tilapiines cannot be properly resolved with presently available methods, for the reasons discussed above. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Tilapiine cichlid」の詳細全文を読む スポンサード リンク
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