Populations genetically rifting within a complex geological system: the case of strong structure and low genetic diversity in the migratory freshwater catfish, Bagrus docmak, in East Africa

Basiita, Rose Komugisha, Zenger, Kyall Richard, and Jerry, Dean Robert (2017) Populations genetically rifting within a complex geological system: the case of strong structure and low genetic diversity in the migratory freshwater catfish, Bagrus docmak, in East Africa. Ecology and Evolution, 7 (16). pp. 6172-6187.

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Abstract

The complex geological history of East Africa has been a driving factor in the rapid evolution of teleost biodiversity. While there is some understanding of how macroevolutionary drivers have shaped teleost speciation in East Africa, there is a paucity of research into how the same biogeographical factors have affected microevolutionary processes within lakes and rivers. To address this deficiency, population genetic diversity, demography, and structure were investigated in a widely distributed and migratory (potamodromous) African teleost species, Ssemutundu (Bagrus docmak). Samples were acquired from five geographical locations in East Africa within two major drainage basins; the Albertine Rift and Lake Victoria Basin. Individuals (N = 175) were genotyped at 12 microsatellite loci and 93 individuals sequenced at the mitochondrial DNA control region. Results suggested populations from Lakes Edward and Victoria had undergone a severe historic bottleneck resulting in very low nucleotide diversity (π = 0.004 and 0.006, respectively) and negatively significant Fu values (−3.769 and −5.049; p < .05). Heterozygosity deficiencies and restricted effective population size (NeLD) suggested contemporary exposure of these populations to stress, consistent with reports of the species decline in the East African Region. High genetic structuring between drainages was detected at both historical (ɸST = 0.62 for mtDNA; p < .001) and contemporary (microsatellite FST = 0.460; p < .001) levels. Patterns of low genetic diversity and strong population structure revealed are consistent with speciation patterns that have been linked to the complex biogeography of East Africa, suggesting that these biogeographical features have operated as both macro- and micro-evolutionary forces in the formation of the East African teleost fauna.

Item ID: 49821
Item Type: Article (Research - C1)
ISSN: 2045-7758
Keywords: aquaculture, Bagrus, genetics, Lake Victoria, microevolution
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This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. © 2017 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.

A version of this publication was included as Chapter 3 of the following PhD thesis: Basiita, Rose Komugisha (2016) Genetic structure and biogeography of three commercially important African freshwater fishes: Lates niloticus, Bagrus docmak and Bagrus bayad. PhD thesis, James Cook University, which is available Open Access in ResearchOnline@JCU. Please see the Related URLs for access.

Funders: NARO-Uganda (NU), AusAID, James Cook University (JCU)
Projects and Grants: NU ATAAS Project, JCU GRS
Date Deposited: 09 Aug 2017 23:33
FoR Codes: 07 AGRICULTURAL AND VETERINARY SCIENCES > 0704 Fisheries Sciences > 070403 Fisheries Management @ 100%
SEO Codes: 83 ANIMAL PRODUCTION AND ANIMAL PRIMARY PRODUCTS > 8302 Fisheries - Wild Caught > 830299 Fisheries- Wild Caught not elsewhere classified @ 100%
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