Testing for hybridization between Nile tilapia (Oreochromis niloticus) and blue spotted tilapia (Oreochromis leucostictus) in the Lake Edward system

Diedericks, Genevieve; Maetens, Heleen; Steenberge, Maarten Van; Snoeks, Jos

doi:10.1016/j.jglr.2021.06.005

Cited by 10 publications

(5 citation statements)

References 41 publications

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“…(2007), Nyingi and Agnèse (2007) and Diedericks et al. (2021), which documented mitochondrial introgression between closely related tilapia species in other locations. For instance, D'Amato et al.…”

Section: Discussionmentioning

confidence: 93%

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Lack of mitochondrial introgression and limited genetic connectivity among Manyara tilapia (Oreochromis amphimelas) populations in Tanzanian Saline Rift Valley Lakes

Morandus,

Rumisha

2024

Afr J Ecol

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The Manyara tilapia (Oreochromis amphimelas), native to the Saline Rift Valley Lakes (SRVLs) in north‐central Tanzania, has recently experienced population declines mainly due to overfishing and severe droughts. This, combined with the introduction of Nile tilapia (O. niloticus), which poses a risk of hybridisation, could potentially erode essential genetic traits necessary for their survival. To address these concerns, our study analysed partial cytochrome oxidase subunit I sequences (627 base pairs) from 139 Manyara tilapia and 79 Nile tilapia specimens collected from the SRVLs to test two hypotheses: (i) whether there is no transfer of mitochondrial DNA between these species, and (ii) whether Manyara tilapia populations in the SRVLs have remained genetically connected despite reported declines. The results revealed six distinct haplotypes for Manyara tilapia and three for Nile tilapia. These haplotypes formed separate clusters for each species, with no shared or closely related haplotypes, indicating limited or no transfer of mitochondrial DNA between them. Additionally, we found evidence of restricted genetic connectivity among Manyara tilapia populations in the SRVLs, with populations in Lakes Manyara and Eyasi displaying limited genetic exchange among themselves and with those in other SRVLs. Our findings highlight the importance of sustained conservation efforts in protected areas around Lake Manyara and Lake Eyasi to safeguard the unique populations of Manyara tilapia in these lakes. However, limited connectivity with other SRVLs suggests that conservation initiatives in these areas may have a limited impact on these lakes. Thus, future efforts should prioritise stocks in Lakes Kindai, Singida and Sulunga, focusing on protecting fish refugia, particularly the rivers connected to these lakes, which serve as critical habitats during the dry season and as important reservoirs for replenishing these populations.

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Section: Discussionmentioning

confidence: 93%

“…Additionally, Diedericks et al. (2021) uncovered one Nile tilapia specimen in Lake Edward that had mitochondrial DNA associated with O. leucostictus .…”

Section: Discussionmentioning

confidence: 99%

Lack of mitochondrial introgression and limited genetic connectivity among Manyara tilapia (Oreochromis amphimelas) populations in Tanzanian Saline Rift Valley Lakes

Morandus,

Rumisha

2024

Afr J Ecol

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Section: Local Genetic Improvement Programmesmentioning

confidence: 99%

“…Repeated hybridization and gene flow between the cultured and wild species (IUCN, 2022) has led to irreversible loss of genetic diversity, reduced environmental adaptability, fitness reduction and potential local extinction of wild populations (Atalah & Sanchez‐Jerez, 2020; Bourret et al, 2011; Wringe et al, 2018). Another example of negative effects of escapes has been the displacement of South African native O. mossambicus from its habitat following hybridization with introduced O. niloticus (Bradbeer et al, 2019; D'Amato et al, 2007; Diedericks et al, 2021). Hybridization between introduced and native species can lead to reduced fitness that may arise from break‐up of co‐adapted gene complexes, that is, disruption of local adaptations that have evolved within the native species over many generations (Muhlfeld et al, 2009).…”

Section: Fish Escape: Impact Of Fish Introductionsmentioning

confidence: 99%

The potential impact of aquaculture on the genetic diversity and conservation of wild fish in sub‐Saharan Africa

Sanda,

Metcalfe,

Mable

2024

Aquatic Conservation

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An increasing focus on aquaculture using introduced strains or species poses a serious threat to native wild species in sub‐Saharan Africa, yet almost no policies have been enacted or regulations put in place to address this environmental challenge. Aquaculture in these regions has traditionally been conducted on a relatively small scale but is currently expanding rapidly and is projected to continue increasing in the coming decades, with increasing use of genetically improved strains. This expansion is occurring in a region known for its high biodiversity, creating challenges for increasing fish production without damaging wild fish populations. However, few studies have yet assessed the impacts of changes in aquaculture practice on the genetic composition and diversity of wild populations. The use of non‐native improved strains for aquaculture could cause competition, gene introgression when there is interbreeding with native populations or species, displacement of species and possible extinction of the native wild populations. After providing historical context on African aquaculture, this review describes the current methods of fish breeding and genetic improvement programmes for the main species of cultured fishes, focusing on the potential conservation impacts of the use of introduced (and selectively bred) farmed species. Existing aquaculture policies, legislation and regulations regarding the import and farming of fish are then compared across the main fish‐producing countries. We recommend a regional policy framework considering fish introduction, risk analysis and risk management, human resources development and genetic monitoring that could be drafted into the existing policies to strengthen conservation efforts. We conclude by making recommendations for refining existing regulations and for future research aimed at minimizing the impacts of aquaculture on wild fish populations in sub‐Saharan Africa. Aquaculture in this region needs implementation of responsible guidelines to avoid genetic impacts on native populations of high conservation value.

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“…He also indicated that the haplotype of Oreochromis leucostictus from Lake Naivasha had been previously described to occur in Oreochromis niloticus from Lake Baringo population. Recent studies in Lake Edward-George system indicate that hybridization between Oreochromis niloticus and Oreochromis leucostictus is happening though rarely (Diedericks et al 2021). Study by Deines et al (2014) found out that the native cichlids Oreochromis macrochir and Oreochromis andersonii hybridize in presence of the Oreochromis niloticus.…”

Section: Oreochromis Leucostictusmentioning

confidence: 99%

Introgressive hybridization levels of Tilapiines species in Lake Victoria basin, Kenya inferred from microsatellite and mitochondrial DNA genotyping based on next- generation sequencing

Gerald

Thapasya

Tibihika³

et al. 2022

Preprint

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Despite their high abundance and species richness, tilapiines have been compromised by various factors especially overfishing, climate change, and un-controlled fish translocations. Fish translocations have negatively impacted native tilapiine populations through competition, predation, hybridization, and introgression compromising their genetic integrity. The hybridization levels of different tilapiines in the Lake Victoria basin remains an understudied aspect relatively. The study utilized nuclear microsatellite and mitochondrial DNA (mtDNA) genetic markers to investigate hybridization signals and compare the genetic diversity of different tilapiines in Lake Victoria, Kenya, using next-generation sequencing. Low levels of hybridization from Oreochromis niloticus into other Oreochromis species were detected by Bayesian clustering analysis and principal coordinate analysis (PCoA). The results contribute to the need for conservation measures of these fish species.

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Testing for hybridization between Nile tilapia (Oreochromis niloticus) and blue spotted tilapia (Oreochromis leucostictus) in the Lake Edward system

Cited by 10 publications

References 41 publications

Lack of mitochondrial introgression and limited genetic connectivity among Manyara tilapia (Oreochromis amphimelas) populations in Tanzanian Saline Rift Valley Lakes

Lack of mitochondrial introgression and limited genetic connectivity among Manyara tilapia (Oreochromis amphimelas) populations in Tanzanian Saline Rift Valley Lakes

The potential impact of aquaculture on the genetic diversity and conservation of wild fish in sub‐Saharan Africa

Introgressive hybridization levels of Tilapiines species in Lake Victoria basin, Kenya inferred from microsatellite and mitochondrial DNA genotyping based on next- generation sequencing

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