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Riverscape genomics of cichlid fishes in the lower Congo: Uncovering mechanisms of diversification in an extreme hydrological regime
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  • Naoko P. Kurata,
  • Michael J. Hickerson,
  • Sandra L. Hoffberg,
  • Ned Gardiner,
  • Melanie L.J. Stiassny,
  • S. Elizabeth Alter
Naoko P. Kurata
American Museum of Natural History
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Michael J. Hickerson
City University of New York The Graduate Center
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Sandra L. Hoffberg
Columbia University
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Ned Gardiner
University of Georgia
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Melanie L.J. Stiassny
American Museum of Natural History
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S. Elizabeth Alter
American Museum of Natural History
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Abstract

Rivers provide excellent models to understand how species diversity is generated and maintained across heterogeneous habitats. The lower Congo River (LCR) consists of a dynamic hydroscape exhibiting extraordinary aquatic biodiversity, endemicity, and ecological specialization. Previous studies have suggested that the numerous high-energy rapids throughout the LCR form physical barriers to gene flow, thus facilitating diversification and speciation, and generating ichthyofaunal diversity. However, this hypothesis has not been fully explored using genome-wide SNPs for fish species distributed across the LCR. In this study, we examined four species of lamprologine cichlids endemic to the LCR, of which three are sequentially distributed along the LCR without range overlap. Using genome-wide SNP data, we tested the hypotheses that high-energy rapids serve as physical barriers to gene flow that generate genetic divergence at inter- and intraspecific levels, and that gene flow occurs primarily in a downstream direction. Our results are consistent with the prediction that the rapids sometimes serve to reduce gene flow, but also suggest that at certain temporal and spatial scales, they may also act as promoters of gene flow. Furthermore, we detected both upstream and downstream gene flow between some populations of Lamprologus tigripictilis as well as hybridization between congeneric species. These results suggest that powerful high-energy rapids may therefore provide occasional multidirectional dispersal opportunities for riverine cichlid fishes, highlighting the complexity of factors driving evolutionary processes in the LCR.
27 Oct 2021Submitted to Molecular Ecology
29 Oct 2021Submission Checks Completed
29 Oct 2021Assigned to Editor
16 Nov 2021Reviewer(s) Assigned
08 Dec 2021Review(s) Completed, Editorial Evaluation Pending
17 Dec 2021Editorial Decision: Revise Minor
10 Mar 2022Review(s) Completed, Editorial Evaluation Pending
10 Mar 20221st Revision Received
11 Mar 2022Reviewer(s) Assigned
28 Mar 2022Editorial Decision: Revise Minor
10 Apr 20222nd Revision Received
10 Apr 2022Review(s) Completed, Editorial Evaluation Pending
04 May 2022Editorial Decision: Accept
Jul 2022Published in Molecular Ecology volume 31 issue 13 on pages 3516-3532. 10.1111/mec.16495