Pathogen exposure reduces sexual dimorphism in a host’s upper thermal limits

Tess Laidlaw, Tobias E. Hector, Carla M. Sgrò, Matthew D. Hall

Research output: Contribution to journalArticleResearchpeer-review

9 Citations (Scopus)


The climate is warming at an unprecedented rate, pushing many species toward and beyond the upper temperatures at which they can survive. Global change is also leading to dramatic shifts in the distribution of pathogens. As a result, upper thermal limits and susceptibility to infection should be key determinants of whether populations continue to persist, or instead go extinct. Within a population, however, individuals vary in both their resistance to both heat stress and infection, and their contributions to vital growth rates. No more so is this true than for males and females. Each sex often varies in their response to pathogen exposure, thermal tolerances, and particularly their influence on population growth, owing to the higher parental investment that females typically make in their offspring. To date, the interplay between host sex, infection, and upper thermal limits has been neglected. Here, we explore the response of male and female Daphnia to bacterial infection and static heat stress. We find that female Daphnia, when uninfected, are much more resistant to static heat stress than males, but that infection negates any advantage that females are afforded. We discuss how the capacity of a population to cope with multiple stressors may be underestimated unless both sexes are considered simultaneously.

Original languageEnglish
Pages (from-to)12851-12859
Number of pages9
JournalEcology and Evolution
Issue number23
Publication statusPublished - Dec 2020


  • aquatic ectotherm
  • Daphnia magna
  • host–parasite interactions
  • Pasteuria ramosa
  • population persistence
  • sex differences
  • static heat stress
  • thermal tolerance

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