Population genomics of introduced Nile tilapia Oreochromis niloticus (Linnaeus, 1758) in the Democratic Republic of the Congo : repeated introductions since colonial times with multiple sources

Geraerts, Mare; Vangestel, Carl; Artois, Tom; Fernandes, Jorge Manuel de Oliveira; Jorissen, Michiel W.P.; Chocha Manda, Auguste; Danadu Mizani, Célestin; Smeets, Karen; Snoeks, Jos; Sonet, Gontran; Tingbao, Yang; Van Steenberge, Maarten; Vreven, Emmanuel; Lunkayilakio Wamuini, Soleil; Vanhove, Maarten P.M.; Huyse, Tine

doi:10.1111/MEC.16479

Title

Population genomics of introduced Nile tilapia Oreochromis niloticus (Linnaeus, 1758) in the Democratic Republic of the Congo : repeated introductions since colonial times with multiple sources

Author

Geraerts, Mare

Vangestel, Carl

Artois, Tom

Fernandes, Jorge Manuel de Oliveira

Jorissen, Michiel W.P.

Chocha Manda, Auguste

Danadu Mizani, Célestin

Smeets, Karen

Snoeks, Jos

Sonet, Gontran

Tingbao, Yang

Van Steenberge, Maarten

Vreven, Emmanuel

Lunkayilakio Wamuini, Soleil

Vanhove, Maarten P.M.

Huyse, Tine

Abstract

During colonial times, Nile tilapia Oreochromis niloticus (Linnaeus, 1758) was introduced into non-native parts of the Congo Basin (Democratic Republic of the Congo, DRC) for the first time. Currently, it is the most farmed cichlid in the DRC, and is present throughout the Congo Basin. Although Nile tilapia has been reported as an invasive species, documentation of historical introductions into this basin and its consequences are scant. Here, we study the genetic consequences of these introductions by genotyping 213 Nile tilapia from native and introduced regions, focusing on the Congo Basin. Additionally, 48 specimens from 16 other tilapia species were included to test for hybridization. Using RAD sequencing (27,611 single nucleotide polymorphisms), we discovered genetic admixture with other tilapia species in several morphologically identified Nile tilapia from the Congo Basin, reflecting their ability to interbreed and the potential threat they pose to the genetic integrity of native tilapias. Nile tilapia populations from the Upper Congo and those from the Middle–Lower Congo are strongly differentiated. The former show genetic similarity to Nile tilapia from the White Nile, while specimens from the Benue Basin and Lake Kariba are similar to Nile tilapia from the Middle–Lower Congo, suggesting independent introductions using different sources. We conclude that the presence of Nile tilapia in the Congo Basin results from independent introductions, reflecting the dynamic aquaculture history, and that their introduction probably leads to genetic interactions with native tilapias, which could lower their fitness. We therefore urge avoiding further introductions of Nile tilapia in non-native regions and to use native tilapias in future aquaculture efforts.

Language

English

Source (journal)

Molecular ecology. - Oxford

Publication

Oxford : 2022

ISSN

0962-1083

DOI

10.1111/MEC.16479

Volume/pages

31 :12 (2022) , p. 3304-3322