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Fish out of water: eco-evolutionary dynamics of rainbowfish populations in the desert
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  • Catherine Attard,
  • Jonathan Sandoval-Castillo,
  • Chris Brauer,
  • Peter Unmack,
  • David Schmarr,
  • Louis Bernatchez,
  • Luciano Beheregaray
Catherine Attard
Flinders University
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Jonathan Sandoval-Castillo
Flinders University
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Chris Brauer
Flinders University
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Peter Unmack
University of Canberra
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David Schmarr
Flinders University
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Louis Bernatchez
Laval University
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Luciano Beheregaray
Flinders University

Corresponding Author:luciano.beheregaray@flinders.edu.au

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Abstract

How populations of aquatic fauna persist in extreme desert environments is an enigma. Individuals often breed and disperse during favourable conditions. However, theory predicts that adaptive capacity should be low in small populations, such as in desert fishes. We integrated satellite-derived surface water data, neutral population dynamics and adaptive evolution to understand metapopulation persistence across the range of the desert rainbowfish, central Australia. Desert rainbowfish showed very small population sizes, especially at peripheral populations, and low connectivity between river catchments. Yet, there was no evidence of population-level inbreeding and there was adaptive divergence associated with aridity. Candidate adaptive genes included functions related to environmental cues and stressful conditions. Evolutionary modelling showed that selection in refugial sub-populations combined with connectivity during flood periods can enable retention of adaptive diversity. Our study demonstrates that adaptive evolution can occur in small populations and integrate with neutral metapopulation processes to allow persistence in the desert.
Jan 2022Published in Evolution volume 76 issue 1 on pages 171-183. https://doi.org/10.1111/evo.14399