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Signatures of natural selection in a foundation tree along Mediterranean climatic gradients
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  • João Filipe,
  • Paul Rymer,
  • Margaret Byrne,
  • Giles Hardy,
  • Richard Mazanec,
  • Collin Ahrens
João Filipe
Murdoch University

Corresponding Author:[email protected]

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Paul Rymer
Western Sydney University
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Margaret Byrne
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Giles Hardy
Murdoch University
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Richard Mazanec
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Collin Ahrens
Western Sydney University
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Temperature and precipitation regimes are rapidly changing, resulting in forest dieback and local extinction events, particularly in Mediterranean-type climates. Strategic forest management approaches that enhance forests’ resilience to future climates are urgently required, however adaptation to climates in heterogeneous landscapes with multiple selection pressures may be complex. For widespread trees in Mediterranean-type climates we hypothesized that patterns of local adaptation are associated with climate; precipitation is a stronger factor of adaptation than temperature; functionally related genes show similar signatures of adaptation; and adaptive variants are independently sorting across the landscape. To test our hypotheses, we sampled 28 populations across the geographic and climatic distribution of Eucalyptus marginata (jarrah), in south-west Western Australia, and obtained 13,534 independent single nucleotide polymorphic (SNP) markers across the genome. While overall levels of population differentiation were low (FST=0.04), environmental association analyses found a total of 2,336 unique SNPs potentially associated with five climate variables of temperature and precipitation. Allelic turnover was identified for SNPs associated with temperate seasonality and mean precipitation of the warmest quarter (39.2% and 36.9% deviance explained, respectively), suggesting that both temperature and precipitation are important factors in adaptation. SNPs within similarly function genes, according to gene ontology enrichment analysis, had analogous allelic turnover along climate gradients, while SNPs among temperature and precipitation variables had orthogonal patterns of adaptation. These contrasting patterns of adaptation provide evidence that there may be standing genomic variation adapted to changing climates, providing the substrate needed to promote adaptive management strategies to bolster forest resilience in the future.
25 Aug 2021Submitted to Molecular Ecology
26 Aug 2021Submission Checks Completed
26 Aug 2021Assigned to Editor
09 Sep 2021Reviewer(s) Assigned
29 Sep 2021Review(s) Completed, Editorial Evaluation Pending
05 Oct 2021Editorial Decision: Revise Minor
12 Nov 2021Review(s) Completed, Editorial Evaluation Pending
12 Nov 20211st Revision Received
16 Nov 2021Reviewer(s) Assigned
06 Dec 2021Editorial Decision: Revise Minor
04 Jan 2022Review(s) Completed, Editorial Evaluation Pending
04 Jan 20222nd Revision Received
10 Jan 2022Editorial Decision: Accept
Mar 2022Published in Molecular Ecology volume 31 issue 6 on pages 1735-1752. 10.1111/mec.16351