Ecological and evolutionary consequences of ecosystem warming in fish

Abstract

Climate warming forces ectothermic organisms to shift their spatial or temporal distribution, acclimatize or adapt to new thermal conditions to survive. Fish, as key ectotherms with significant ecological roles and socio-economic values, have been widely studied in this context. However, whether warming induces evolution in wild fish populations over time, and if so, how such evolutionary effects can impact the community and ecosystem more broadly remain largely unknown.

In this thesis, I investigated the effects of ecosystem-warming on fish by comparing traits and genomes of Eurasian perch from an artificially heated area with those from a neighbouring unheated area over four decades. Long-term trait data analyses showed that perch mature earlier and at smaller body sizes with increased reproductive investment in the first generations exposed to warming. After four to eight generations of warming, size at maturation varied more, indicating an evolutionary component in maturation-related trait responses to warming. Utilising a customised DNA extraction protocol, I obtained high-quality whole genome sequencing data for perch from historical archival bones as well as contemporary muscle samples. Selection signatures in single nucleotide variants were revealed between perch from the heated and unheated area over time, suggesting natural selection due to warming. Lastly, I conducted a mesocosm experiment, exposing a pelagic food web module to a temperature gradient using perch larvae from both the heated and unheated areas. Fish from the heated area may have adapted to warming in feeding-related traits, as indicated by differences in their zooplankton prey community composition compared to fish from the unheated area.

Overall, the thesis demonstrates that warming can impose evolutionary and ecological consequences on fish in the wild, and underscores how such consequences can propagate through species interactions and influence other components in the ecosystem. This thesis emphasises the importance of synthesising research on ecology and evolution to better understand how ectotherms respond to rising temperatures and the biological processes involved, especially in the face of intensifying climate warming challenges.

Keywords

climate change; life history trait; maturation; food webs; trophic interactions; ecological genomics; thermal biology; evolutionary biology; Eurasian perch

Published in

Acta Universitatis Agriculturae Sueciae
2025, number: 2025:15
Publisher: Swedish University of Agricultural Sciences

SLU Authors

• Niu, Jingyao

  • Department of Aquatic Resources (SLU Aqua), Swedish University of Agricultural Sciences
    

Associated SLU-program

Coastal and sea areas
Climate
Use of FOMA data

UKÄ Subject classification

Ecology
Evolutionary Biology
Genetics and Genomics

Publication identifier

• DOI: https://doi.org/10.54612/a.5bofv951fm
• ISBN: 978-91-8046-450-5
• eISBN: 978-91-8046-500-7

Permanent link to this page (URI)

https://res.slu.se/id/publ/132955