BACKGROUND: Tilapia zillii is widespread in the East Levant inland aquatic systems as well as in artificial water reservoirs. In this study we explore the genetic and morphological variation of this widespread species, using mitochondrial control-region sequences and meristic characters. We examine the hypothesis that T. zilli's population structure corresponds to the four Israeli aquatic systems. RESULTS: Out of seven natural water bodies, only two were found to possess genetically divergent populations of T. zillii. In addition to its presence in fish farms, the species was found in two artificial recreational ponds which were supposed to have been stocked only with other fish species. In these two artificial habitats, the haplotype frequencies diverged significantly from those of natural populations. Finally, fish from the Dead Sea springs of Ne'ot HaKikar appear to differ both genetically and morphologically from fish of the same aquatic system but not from fish of other water systems. CONCLUSIONS: Our results show that the population structure of T. zillii does not match the geography of the Israeli water-basins, with the exception of the Dead Sea and Kishon River, when considering natural populations only. The absence of a significant divergence between basins is discussed. Our results and observations suggest that the Ne'ot HaKikar Dead Sea population and those of artificial ponds could have originated from the "hitchhiking" of T. zillii, at the expense of some other cultivated tilapiine species.
DLoop_T_Zillii
Tilapia zillii D-loop sequence alignment in Fasta format. TAUP numbers are voucher specimens deposited in the National Collection of Natural History at Tel- Aviv University. Haplotype numbers are specified. Populations and basins of origin are denoted as follows: TM, Taninim (coastal); EA, Ein Afek (coastal); KN, Kishon (Kishon); KT, Kinneret (Jordan); BS, Beit She’an (Jordan); EF, Ein Feshkha (Dead Sea); NH, Ne’ot HaKikar (Dead-Sea introduced); RG, Ramat Gan (coastal introduced); NM, Nitzanim (coastal introduced); MA, HaMa'apil (coastal introduced). Haplotypes of each population have been submitted under under accession numbers EU163705-EU163723 and FJ613474-FJ613479
meristics
Counts of meristic characters in Tilapia zillii. TAUP numbers are voucher specimens deposited in the National Collection of Natural History at Tel- Aviv University. Populations of origin are denoted as follows: TM, Taninim (coastal); EA, Ein Afek (coastal); KN, Kishon (Kishon); KT, Kinneret (Jordan); BS, Beit She’an (Jordan); EF, Ein Feshkha (Dead Sea); NH, Ne’ot HaKikar (Dead-Sea introduced); RG, Ramat Gan (coastal introduced); NM, Nitzanim (coastal introduced); MA, HaMa'apil (coastal introduced). The characters considered are denoted as follows: LL1, Number of scales along the upper lateral line; LL2, Number of scales along the lower lateral line; TR1, Number of scales between the dorsal fin and the upper lateral line; TR2, Number of scales between the upper and lower lateral line; TR3, Number of scales between the lower lateral line and the anal fin; P, Number of rays in the pectoral fin; Pbr, Number of branched rays in the pectoral fin; V, Number of rays in the ventral fin; Vbr, Number of branched rays in the ventral fin; D, Number of rays in the dorsal fin; Dbr, Number of branched rays in the dorsal fin; DS, Number of spikes in the dorsal fin; A, Number of rays in the anal fin; Abr, Number of branched rays in the anal fin; AS, Number of spikes in the anal fin; C, Number of rays in the caudal fin; Cbr, Number of branched rays in the caudal fin; LPR, The position of the longest pectoral ray; LVR, The position of the longest ventral ray; LDR, The position of the longest dorsal ray; LAR, The position of the longest anal ray; GR, The number of gill rakers