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Sammanfattning

The extent to which different magnitudes and directions of temperature fluctuations explain long-term trends in aquatic invertebrate body size is largely unknown. Using elevational gradients and paleolimnological reconstructions, we tested the hypotheses that the size of subfossil chironomid (non-biting midges) head capsules (HCs) will covary with temperature changes, with opposite morphometric changes occurring during warming and cooling phases, and that body size variation can be modified by other environmental conditions unassociated with temperature variations. Results indicated that the effects of increasing temperatures on chironomid HC size were reversed when temperatures decreased, with both warming and cooling producing similar effect sizes, corresponding to a change in HC length of similar to 3% per 1 degrees C. Additionally, our results showed that other environmental drivers can mask temperature effects on chironomid HC sizes. Specifically, we found that bottom water oxygen concentration was negatively associated with HC lengths of Chironomus anthracinus-type. We hypothesize that this pattern is driven by prolonged larval development in oxygen-depleted lakes and/or changes in basal food sources used by chironomid larvae, ultimately affecting their final body size. Future research should focus on disentangling the multiple drivers that control body size in aquatic insects, given their potential to either enhance or confound the temperature-size relationship, to improve our mechanistic understanding of aquatic insect size variation over long timescales.

Nyckelord

Body size variation; chironomidae; climate change; paleolimnology; phenotypic plasticity

Publicerad i

Oikos
2025, artikelnummer: e11370
Utgivare: WILEY

SLU författare

UKÄ forskningsämne

Ekologi

Publikationens identifierare

  • DOI: https://doi.org/10.1002/oik.11370

Permanent länk till denna sida (URI)

https://res.slu.se/id/publ/143060