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Can phenology and plasticity prevent adaptive clines in tolerance limits across temperate mountains?
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  • Luis Gutiérrez-Pesquera,
  • Miguel Tejedo,
  • Agustin Camacho,
  • Urtzi Enríquez-Urzelai,
  • Marco Katzenberger,
  • Magdalena Choda,
  • Pol Pintanel,
  • Alfredo Nicieza
Luis Gutiérrez-Pesquera
Estación Biológica de Doñana
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Miguel Tejedo
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Agustin Camacho
Universidade de São Paulo
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Urtzi Enríquez-Urzelai
Institute of Vertebrate Biology Czech Academy of Sciences
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Marco Katzenberger
Universidade Federal de Pernambuco
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Magdalena Choda
University of Oviedo
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Pol Pintanel
Estación Biológica de Doñana
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Alfredo Nicieza
University of Oviedo
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Abstract

Critical thermal limits (CTmax and CTmin) are predicted to decrease with elevation, with greater change in CTmin, and the risk to suffer heat and cold stress increasing at the gradient ends. A central prediction is that populations will adapt to the prevailing climatic conditions. Yet, reliable support for such expectation is scant because of the complexity of integrating phenotypic and molecular divergence. We propose that phenotypic plasticity and breeding phenology may hinder local adaptation cancelling the appearance of adaptive patterns. We examined intraspecific variation of CTmax/CTmin in 11 populations of an amphibian across an elevational gradient, and assessed (1) the existence of local adaptation through a PST-FST comparison, (2) the acclimation scope in both thermal limits, and (3) the vulnerability to suffer acute heat (CTmax–tmax) and cold (tmin–CTmin) thermal stress, measured at both macro- and microclimatic scales. Our study revealed significant microgeographic variation in CTmax/CTmin, and unexpected elevation gradients in pond temperatures. However, variation in CTmax/CTmin could not be attributed to selection because critical thermal limits were not correlated to elevation or temperatures. Differences in breeding phenology among populations resulted in exposure to higher and more variable temperatures at mid and high elevations. Accordingly, mid- and high-elevation populations had higher CTmax and CTmin plasticities than lowland populations, but not more extreme CTmax/CTmin. Thus, we confirm our prediction that plasticity and phenological shifts may hinder local adaptation, promoting thermal niche conservatism and a higher vulnerability to climate change. This contradicts some of the existing predictions on adaptive thermal clines.

Peer review status:UNDER REVIEW

23 Jul 2021Submitted to Molecular Ecology
24 Jul 2021Assigned to Editor
24 Jul 2021Submission Checks Completed
06 Aug 2021Reviewer(s) Assigned