Skip to main content
Dryad

Does fluctuating asymmetry of wing traits capture relative environmental stress in a lepidopteran?

Data files

Nov 04, 2021 version files 81.06 KB

Abstract

Fluctuating asymmetry (FA) may be a useful predictor of population canalization, especially for organisms at risk from environmental change.

  1. Identification of traits that meet statistical criteria as FA measures remains a challenge.

  2. In the present study, a laboratory experiment subjected immature butterflies (Vanessa cardui) to a range of diet and temperature conditions of varying stress levels. Variation in dietary macronutrient ratio (protein: carbohydrate) and rearing temperature (optimal: 25°C; elevated: 32°C) were introduced as stressors.

  3. Individuals subjected to stressful conditions were predicted to show elevated FA of three wing size traits.

  4. While FA of all three traits proved measurable, it did not vary across diet and temperature treatments. Instead, treatment levels impacted viability: the combined incidence of death prior to eclosion and expression of significant wing malformations increased in treatment levels predicted to increase FA. Variation in adult dry mass also reflected predicted stress levels. Results suggest that predicted FA variation was not found because individuals predicted to display increased FA either died or displayed gross developmental aberrations.

  5. This experiment illustrates important constraints on the investigation of FA, including selection of appropriate traits and identification of appropriate levels of stressors to avoid elevated mortality. The latter concern brings into question the utility of FA as an indicator of stress in vulnerable, natural populations, where stress levels are rarely controlled, and mortality and fitness effects are often not quantifiable.