Oreochromis urolepis hornorum
| Wami tilapia | |
|---|---|
Scientific classification
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Cichliformes |
| Family: | Cichlidae |
| Genus: | Oreochromis |
| Species: | |
| Subspecies: | O. u. hornorum
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| Trinomial name | |
| Oreochromis urolepis hornorum (Trewavas,1966)
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| Synonyms | |
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TheWami tilapiais atilapiinecichlidthat grows to over 20 cm in length and is considered a useful foodfishinTanzaniaand the island ofZanzibar,which is recognized as a potential origin. It is tolerant ofbrackishwater and grows well in saline pools, making it particularly suitable for aquaculture by communities living close to the sea. Like othertilapia,it is anomnivoreand will feed on algae, plants, small invertebrates, and detritus. The common name refers to theWami River.
Formerly considered a separatespecies,it is at present merged with theRufigi tilapiaand thus thescientific nameisOreochromis urolepis hornorum.The obsolete scientific nameTilapia hornorumis also still seen not infrequently. However,mtDNAsequenceanalysis has found that themitochondrial genomeis possibly very similar to that ofSarotherodon galilaeus(Naglet al.2001); it might be moved toSarotherodonbased on these results. On the other hand,hybridizationis quite common in tilapiines and hybrids even between not too closely related species may be fertile.
In captivity, Wami tilapia have been hybridised with theMozambique tilapia(Oreochromis mossambicus). The resulting fish produce broods almost entirely consisting of males. Male tilapia grow faster and to a more uniform size than females, making them particularly useful foraquaculture.[2]Note that based on the mtDNA study by Naglet al.(2001), the Mozambique and Wami tilapias do not appear to be closely related.
3 possibilities may explain this discrepancy: Either, the Wami tilapia and its closest relatives (such as the Rufigi andBlue Tilapias) belong intoSarotherodon.Alternatively, they are correctly placed inOreochromisbut their ancestors hybridized with some ancestralSarotherodon.Given that only a single specimen was analyzed, it is theoretically also possible that the Wami tilapia is acryptic species complex.This is less likely because cryptic speciation requires barriers togene flowwhich in the tilapiines are not well-developed.
The mtDNA data of Klett & Meyer (2002) places the Rufigi tilapia intoOreochromis(though not close to the Mozambique Tilapia, but rather toOreochromis amphimelas). This would seem to support the second hypothesis - maternal gene flow fromSarotherodontoOreochromis;whether this is correct or not, it amply illustrates that mtDNA sequences are not a reliable indicator of phylogenetic relationships in these fish.
References
[edit]- ^Hanssens, M & Snoeks, J. (2010)."Oreochromis urolepis ssp. hornorum".IUCN Red List of Threatened Species.2010:e.T183074A8054087.Retrieved9 February2019.
- ^Frank A. Chapman.Culture of Hybrid Tilapia: A Reference Profile
- Klett, Vera & Meyer, Axel(2002): What, if Anything, is a Tilapia? Mitochondrial ND2 Phylogeny of Tilapiines and the Evolution of Parental Care Systems in the African Cichlid Fishes.Molecular Biology and Evolution19(6): 865-883.
- Nagl, Sandra; Tichy, Herbert; Mayer, Werner E.; Samonte, Irene E.; McAndrew, Brendan J. & Klein, Jan(2001): Classification and Phylogenetic Relationships of African Tilapiine Fishes Inferred from Mitochondrial DNA Sequences.Molecular Phylogenetics and Evolution20(3): 361–374.doi:10.1006/mpev.2001.0979