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Recent Polygenic Adaptation in Heavily Fished Malawi Cichlids
Alexander Hooft van Huysduynen1,2, Francisco Campuzano Jiménez1, Julia Camacho Garcia1
1Evolutionary Ecology Group, Department of Biology, University of Antwerp, Antwerp, Belgium.
Molecular Ecology
|June 22, 2026
Summary
Intense fishing rapidly drives evolution in cichlid fish, altering genes for growth and reproduction. This polygenic adaptation reshapes life-history traits, impacting fisheries sustainability.
Area of Science:
- Evolutionary biology
- Genomics
- Fisheries science
Background:
- Intense fishing pressure can accelerate evolution in wild populations.
- Genomic underpinnings of rapid adaptation to harvesting are often unclear.
Purpose of the Study:
- Investigate genomic changes in Copadichromis mloto due to five decades of intense fishing.
- Identify genes and genetic mechanisms driving rapid adaptation in response to harvesting.
Main Methods:
- Compared whole-genome data from nearly 200 individuals from heavily fished (Lake Malombe) and less-fished (Lake Malawi) populations.
- Analyzed genomic footprints of positive selection and gene expression in gonad tissue.
Main Results:
- Identified widespread, population-specific positive selection across hundreds of genetic loci.
- Candidate genes under selection are enriched for developmental processes (neurogenesis, heart, muscle) and somatic growth/reproduction.
- Selected genes showed higher differential expression in male gonad tissue, linking selection to reproductive organ changes.
Conclusions:
- Fisheries-induced evolution in this cichlid population has a polygenic basis.
- Intense harvesting rapidly reshapes the genetic architecture of life-history traits.
- Findings have implications for the resilience of exploited fish stocks.
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