The genomic basis of cichlid fish adaptation within the deepwater “twilight zone” of Lake Malawi

Genner, Martin J.; Turner, George F.; Hahn, Christoph; Genner, Martin J; Turner, George F; Joyce, Domino A.

Abstract

Deepwater environments are characterized by low levels of available light at narrow spectra, great hydrostatic pressure, and low levels of dissolved oxygen—conditions predicted to exert highly specific selection pressures. In Lake Malawi over 800 cichlid species have evolved, and this adaptive radiation extends into the “twilight zone” below 50 m. We use population-level RAD-seq data to investigate whether four endemic deepwater species (Diplotaxodon spp.) have experienced divergent selection within this environment. We identify candidate genes including regulators of photoreceptor function, photopigments, lens morphology, and haemoglobin, many not previously implicated in cichlid adaptive radiations. Colocalization of functionally linked genes suggests coadapted “supergene” complexes. Comparisons of Diplotaxodon to the broader Lake Malawi radiation using genome resequencing data revealed functional substitutions and signatures of positive selection in candidate genes. Our data provide unique insights into genomic adaptation within deepwater habitats, and suggest genome-level specialization for life at depth as an important process in cichlid radiation.

Citation

Genner, M. J., Turner, G. F., Hahn, C., Genner, M. J., Turner, G. F., & Joyce, D. A. (2017). The genomic basis of cichlid fish adaptation within the deepwater “twilight zone” of Lake Malawi. Evolution Letters, 1(4), 184-198. https://doi.org/10.1002/evl3.20

• Journal Article Type: Letter
• Acceptance Date: Jul 11, 2017
• Online Publication Date: Aug 29, 2017
• Publication Date: 2017-09
• Deposit Date: Aug 6, 2018
• Publicly Available Date: Aug 6, 2018
• Journal: Evolution Letters
• Print ISSN: 2056-3744
• Publisher: Wiley
• Peer Reviewed: Peer Reviewed
• Volume: 1
• Issue: 4
• Pages: 184-198
• DOI: https://doi.org/10.1002/evl3.20
• Keywords: Cichlid; Hemoglobin; Root effect; Sensory drive; Supergene
• Public URL: https://hull-repository.worktribe.com/output/765870
• Publisher URL: https://onlinelibrary.wiley.com/doi/abs/10.1002/evl3.20
• Related Public URLs: https://research.bangor.ac.uk/portal/files/19695049/2017_The_genomic_basis_of_cichlid_fish_adaptation_within_the_deep_water_twighlight_zone_.pdf
• Contract Date: Aug 6, 2018