Episodes of opposing survival and reproductive selection cause strong fluctuating selection on seasonal migration versus residence

Paul Acker* (Corresponding Author), Sarah J. Burthe* (Corresponding Author), Mark A. Newell, Hannah Grist, Carrie Gunn, Michael P. Harris, Ana Payo-Payo, Robert Swann, Sarah Wanless, Francis Daunt, Jane M. Reid

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)
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Quantifying temporal variation in sex-specific selection on key ecologically relevant traits, and quantifying how such variation arises through synergistic or opposing components of survival and reproductive selection, is central to understanding eco-evolutionary dynamics, but rarely achieved. Seasonal migration versus residence is one key trait that directly shapes spatio-seasonal population dynamics in spatially and temporally varying environments, but temporal dynamics of sex-specific selection have not been fully quantified. We fitted multi-event capture-recapture models to year-round ring resightings and breeding success data from partially migratory European shags (Phalacrocorax aristotelis) to quantify temporal variation in annual sex-specific selection on seasonal migration versus residence arising through adult survival, reproduction and the combination of both (i.e. annual fitness). We demonstrate episodes of strong and strongly fluctuating selection through annual fitness that were broadly synchronized across females and males. These overall fluctuations arose because strong reproductive selection against migration in several years contrasted with strong survival selection against residence in years with extreme climatic events. These results indicate how substantial phenotypic and genetic variation in migration versus residence could be maintained, and highlight that biologically important fluctuations in selection may not be detected unless both survival selection and reproductive selection are appropriately quantified and combined.

Original languageEnglish
Article number20210404
Number of pages10
JournalProceedings of the Royal Society B: Biological Sciences
Issue number1951
Early online date19 May 2021
Publication statusPublished - 26 May 2021

Bibliographical note

We thank everyone who contributed to fieldwork (ESM S7), particularly Raymond Duncan, Moray Souter, Jenny Sturgeon, Hanna Granroth-Wilding, Katherine Herborn, Olivia Hicks, Richard Howells, Ruth Dunn, Alice Carravieri, Tom Reed and Morten Frederiksen; UK Natural Environment Research Council (NE/R000859/1; NE/R016429/1 through the UK487 SCaPE programme delivering National Capability; NE/M005186/1) and Joint Nature Conservation Committee for funding; Sarah Fenn for helpful comments; and NatureScot for access to the IoM NNR.


  • annual fitness
  • extreme climatic event
  • fecundity selection
  • multi-event capture-recapture
  • partial migration
  • sex-specific selection
  • multi-event capture–recapture


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