Comparative studies of critical physiological limits and vulnerability to environmental extremes in small ectotherms: How much environmental control is needed?

Ary A. Hoffmann, Carla M. Sgrò

Research output: Contribution to journalReview ArticleResearchpeer-review

39 Citations (Scopus)


Researchers and practitioners are increasingly using comparative assessments of critical thermal and physiological limits to assess the relative vulnerability of ectothermic species to extreme thermal and aridity conditions occurring under climate change. In most assessments of vulnerability, critical limits are compared across taxa exposed to different environmental and developmental conditions. However, many aspects of vulnerability should ideally be compared when species are exposed to the same environmental conditions, allowing a partitioning of sources of variation such as used in quantitative genetics. This is particularly important when assessing the importance of different types of plasticity to critical limits, using phylogenetic analyses to test for evolutionary constraints, isolating genetic variants that contribute to limits, characterizing evolutionary interactions among traits limiting adaptive responses, and when assessing the role of cross generation effects. However, vulnerability assessments based on critical thermal/physiological limits also need to take place within a context that is relevant to field conditions, which is not easily provided under controlled environmental conditions where behavior, microhabitat, stress exposure rates and other factors will differ from field conditions. There are ways of reconciling these requirements, such as by taking organisms from controlled environments and then testing their performance under field conditions (or vice versa). While comparisons under controlled environments are challenging for many taxa, assessments of critical thermal limits and vulnerability will always be incomplete unless environmental effects within and across generations are considered, and where the ecological relevance of assays measuring critical limits can be established.

Original languageEnglish
Pages (from-to)355-371
Number of pages17
JournalIntegrative Zoology
Issue number4
Publication statusPublished - 1 Jul 2018


  • common garden
  • comparative studies
  • critical limits
  • ectotherms
  • environmental control
  • stress resistance
  • thermal limits

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