Tilapiine fishes of the genera Sarotherodon, Oreochromis, and Danakilia /

Trewavas, Ethelwynn

doi:10.5962/bhl.title.123198

Cited by 675 publications

(779 citation statements)

References 0 publications

Supporting

Mentioning

695

Contrasting

Unclassified

Order By: Relevance

“…The diet of O. leucostictus has been observed to consist predominantly of phytoplankton (Trewavas 1983). In the present study, the differences in condition of O. leucostictus among lakes with high fishing pressure and the lakes with low to medium fishing pressure may reflect a greater availability of phytoplankton in response to reduction in population density caused by fishing.…”

Section: Discussionmentioning

confidence: 62%

Fish condition in introduced tilapias of Ugandan crater lakes in relation to deforestation and fishing pressure

2009

View full text Add to dashboard Cite

This study identifies environmental predictors of the condition of two introduced tilapia species (Oreochromis leucostictus and Tilapia zillii) that are known to have divergent trophic niches (planktivore and herbivore, respectively) in 17 crater lakes in western Uganda. We asked whether fish condition differs among lakes characterized by differences in fishing pressure and catchment deforestation; and we related relative condition factor to gradients of environmental variation across lakes. Lakes characterized by severe catchment deforestation tended to be lakes with high fishing pressure, so it was difficult to explore independent and interactive effects. However, mean relative condition factor was higher in populations with high fishing pressure compared to populations with low fishing pressure for both O. leucostictus and T. zillii. The condition of O. leucostictus populations was higher in lakes with severely deforested catchments; but mean relative condition factor of T. zillii did not differ between deforestation categories. Principal components analysis (PCA) was used to describe the major environmental gradients of variation among the lakes; and PCA factor scores were regressed against relative fish condition. The association between fish condition and environmental gradients was stronger for O. leucostictus than for T. zillii. For O. leucostictus, fish condition was related to PC1 (43% of the variance) and factors that loaded most heavily included Chl-a, water transparency, lake area and depth, suggesting higher condition in lakes characterized by higher primary productivity and smaller size. For T. zillii, PC3 (11%) was the only axis related to fish condition; and factors that loaded most heavily included lake area (positive), and conductivity and total nitrogen (negative). Some of the larger lakes are characterized by higher availability of macrophytes that may positively affect the food base for T. zillii.

show abstract

Section: Discussionmentioning

confidence: 62%

Fish condition in introduced tilapias of Ugandan crater lakes in relation to deforestation and fishing pressure

2009

View full text Add to dashboard Cite

show abstract

“…These climatic changes (Maley, 1991) could explain the genetic structure of some fish populations in West Africa (Agnese, 1989;Adépo-Gourène et aL, 1997). In East Africa, many tectonic movements and much volcanic activity have had a major role in the formation of the different basins and then in the distribution of fish species (Fryer & lIes, 1972;Trewavas, 1983).…”

Section: Biogeographymentioning

confidence: 99%

“…They are of great economic interest, either in fisheries or in aquaculture. Among all the species, the Nile tilapia, Oreochromis niloticus (Linnaeus, 1758), originating in West and East Africa (Trewavas, 1983), is commercially the most important. It has been introduced into many Asian and South American countries.…”

Section: Introductionmentioning

confidence: 99%

Genetic differentiation among natural populations of the Nile tilapia Oreochromis niloticus (Teleostei, Cichlidae)

Agnèse

Adépo-Gourène

Abban³

et al. 1997

Heredity

View full text Add to dashboard Cite

We analysed the genetic differentiation among 17 natural populations of the Nile tilapia Oreochromis niloticus (Linnaeus, 1758) using allozymes and restriction fragment length polymorphism (RFLP) of mitochondrial DNA (mtDNA). The populations studied, from the River Senegal to Lake Tana and from Lake Manzalla to Lake Baringo, represent all subspecies which have been previously described. Sixteen variable nuclear loci showed that these populations can be clustered in three groups: (1) West African populations (Senegal, Niger, Volta and Chad drainages), (2) Ethiopian Rift Valley populations (Lakes Awasa, Ziway, Koka and the Awash River) and (3) Nile drainage (Manzalla, Cairo, Lake Edward) and Kenyan Rift Valley populations (Lakes Turkana, Baringo and River Suguta). Nine different mtDNA haplotypes were found in the RFLP analysis of a 1 kb portion of the D-loop region. The network obtained showed that there are three geographically distinct groups; all West African populations and 0. aureus are clustered, the two Ethiopian Rift Valley populations are distinct and between these two groups are the Kenyan and Ugandan Rift Valley populations. Nile populations show affinities both with West African populations and with specimens from Lakes Tana and Turkana. Taxonomic and biogeographical implications of these results are discussed.

show abstract

“…In EA, Nile tilapia is native to the Lakes George, Edward, Albert, Kivu, Tanganyika, Turkana, Baringo and to the River Nile (Trewavas 1983;Ogutu-Ohwayo 1990;Agnèse et al 1997). The cichlid was introduced to the remaining large water bodies, lakes Victoria, Kyoga, Nabugabo and to numerous satellite lakes including various aquaculture setups (Ogutu-Ohwayo 1990;Boyd 2004).…”

Section: Introductionmentioning

confidence: 99%

“…In EA, Trewavas (1983) and Vreven et al (1998), delineated Nile tilapia morphotypes employing traditional morphometrics (TM). This involves physical linear measurements of the fish anatomical parts like head length, body depth, total length, standard length, eye diameter, fin lengths, mouth gape length, among others.…”

Section: Introductionmentioning

confidence: 99%

Anthropogenic impacts on the contextual morphological diversification and adaptation of Nile tilapia (Oreochromis niloticus, L. 1758) in East Africa

et al. 2018

View full text Add to dashboard Cite

Nile tilapia occurs naturally in East Africa where it's an economically important species. Many of the natural populations of Nile tilapia have been affected by anthropogenic activities including translocations, associated with programmes aimed at enhancing capture fisheries and aquaculture productivity. Using geometric morphometric analyses, we tested the hypothesis that such anthropogenic activities have augmented admixture among natural populations of Nile tilapia and influenced the geographical distribution of morphological variation within the species. Our expectation was that Nile tilapia shape divergent might be consistent with reportedly anthropogenic activities in nonnative environments. To test this hypothesis, we analyzed the shapes of 490 individuals from thirteen populations; three farms, six natives and four nonnative natural populations. Our analysis revealed that the most pronounced shape diversification was observed in seven populations; three nonnatives (Victoria, Kyoga and Sindi farm) and four natives (Albert, River Nile, George and Turkana). The features responsible for the observed morphotypes were mainly related to the orientation of the anterior region of the fish and may be due to diversifying selection in response to new environmental pressures (for nonnative populations), admixture or drift. Shape change in the nonnative high-altitude populations was unexpectedly conserved, suggesting recent introductions which may have not resulted in admixture or there was strong selection against change in the traits measured. On the other hand, the recorded morphotypic clusters explained the possible genetic link to their putative ancestral home. Our results were partially consistent with our prediction that the nonnative populations exhibited divergent morphotypes. We recommend further investigations with molecular genetics for followup of these findings.

show abstract

Tilapiine fishes of the genera Sarotherodon, Oreochromis, and Danakilia /

Cited by 675 publications

References 0 publications

Fish condition in introduced tilapias of Ugandan crater lakes in relation to deforestation and fishing pressure

Fish condition in introduced tilapias of Ugandan crater lakes in relation to deforestation and fishing pressure

Genetic differentiation among natural populations of the Nile tilapia Oreochromis niloticus (Teleostei, Cichlidae)

Anthropogenic impacts on the contextual morphological diversification and adaptation of Nile tilapia (Oreochromis niloticus, L. 1758) in East Africa

Contact Info

Product

Resources

About