Intraspecific variation reshapes coral assemblages under elevated temperature and acidity

Michael McWilliam*, Joshua Madin, Tory Chase, Mia O Hoogenboom, Tom Bridge

*Corresponding author for this work

Research output: Contribution to journalLetterpeer-review

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Insights into assemblages that can persist in extreme environments are still emerging. Ocean warming and acidification select against species with low physiological tolerance (trait-based ‘filtering’). However, intraspecific trait variation can promote species adaptation and persistence, with potentially large effects on assemblage structure. By sampling nine coral traits (four morphological, four tissue and one skeletal) along an offshore–inshore gradient in temperature and pH, we show that distantly related coral species undergo consistent intraspecific changes as they cross into warm, acidic environment. Intraspecific variation and species turnover each favoured colonies with greater tissue biomass, higher symbiont densities and reduced skeletal investments, indicating strong filtering on colony physiology within and across species. Physiological tissue traits were highly variable within species and were independent of morphology, enabling morphologically diverse species to cross into sites of elevated temperature and acidity. Widespread intraspecific change can therefore counter the loss of biodiversity and morphological structure across a steep environmental gradient.
Original languageEnglish
Pages (from-to)2513-2524
Number of pages12
JournalEcology Letters
Issue number11
Early online date9 Oct 2022
Publication statusPublished - 26 Oct 2022


  • Adaptation
  • Community assembly
  • Coral reefs
  • Functional traits
  • Phenotypic plasticity
  • Physiology


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