Biology subjects

Genner, M. J.

Publications and source records attributed to Genner, M. J..

3 recordsLinked to original sources

bioRxiv2018

A survey of fishes of Hombolo Lake, Dodoma, Tanzania, with evidence for local extinction of a native tilapia as a consequence of stocking

The fish community of the Hombolo Lake, an impoundment on the Wami catchment near Dodoma, Tanzania, was surveyed in 2014 and 2017. The lake contains a relatively low diversity community dominated by two Oreochromis species introduced from outside the Wami catchment, O. niloticus and O. esculentus. Evidence from historical collections suggests that the native O. urolepis was formerly present, and its current absence is likely to be the result of competitive exclusion or genetic swamping by non-native species introduced for fishery enhancement. Four other fish species were also recorded.

ecology↗

bioRxiv2017

Whole Genome Sequences Of Malawi Cichlids Reveal Multiple Radiations Interconnected By Gene Flow

The hundreds of cichlid fish species in Lake Malawi constitute the most extensive recent vertebrate adaptive radiation. Here we characterize its genomic diversity by sequencing 134 individuals covering 73 species across all major lineages. Average sequence divergence between species pairs is only 0.1-0.25%. These divergence values overlap diversity within species, with 82% of heterozygosity shared between species. Phylogenetic analyses suggest that diversification initially proceeded by serial branching from a generalist Astatotilapia-like ancestor. However, no single species tree adequately represents all species relationships, with evidence for substantial gene flow at multiple times. Common signatures of selection on visual and oxygen transport genes shared by distantly related deep water species point to both adaptive introgression and independent selection. These findings enhance our understanding of genomic processes underlying rapid species diversification, and provide a platform for future genetic analysis of the Malawi radiation.\n\nOne Sentence Summary: The genomes of 73 cichlid fish species from Lake Malawi uncover evolutionary processes underlying a large adaptive evolutionary radiation.

evolutionary biology↗

bioRxiv2017

The genomic basis of adaptation to the deep water ‘twilight zone’ in Lake Malawi cichlid fishes

Deep water environments are characterized by low levels of available light at increasingly narrow spectra, great hydrostatic pressure and reduced 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 100 metres. We use population-level RAD-seq data to investigate whether four endemic deep water 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. Co-localization of functionally linked genes suggests co-adapted \"supergene\" complexes. Comparisons of Diplotaxodon to the broader Lake Malawi radiation using genome resequencing data revealed functional substitutions in candidate genes. Our data provide unique insights into genomic adaptation to life at depth, and suggest genome-level specialisation for deep water habitat as an important process in cichlid radiation.

evolutionary biology↗