DISSECTING CORRELATED CHARACTERS: ADAPTIVE ASPECTS OF PHENOTYPIC COVARIATION IN MELANIZATION PATTERN OF PIERIS...

Area of Science:

• Evolutionary Biology
• Ecology
• Animal Behavior

Background:

• Phenotypic variation within populations is shaped by both adaptive and non-adaptive processes.
• Understanding the adaptive basis of covariation among phenotypic traits is crucial for evolutionary studies.
• Wing melanization in butterflies is linked to thermoregulation and can exhibit significant variation.

Purpose of the Study:

• To investigate the extent to which covariation among wing melanization patterns in Pieris butterflies is adaptive.
• To test predictions derived from functional analyses of thermoregulatory performance.
• To analyze adaptive covariation at both biogeographic and within-population (seasonal plasticity) levels.

Main Methods:

• Quantification and analysis of wing melanization patterns in Pieris populations from cool North American environments.
• Comparison of observed covariation with a priori predictions based on thermoregulatory hypotheses.
• Examination of biogeographic variation and seasonal polyphenism (phenotypic plasticity).

Main Results:

• The adaptive hypothesis successfully predicted qualitative features of melanization covariation across major wing regions for Pieris occidentalis populations.
• Agreement with adaptive predictions varied within populations for both Pieris occidentalis and Pieris napi, with P. napi showing poorer agreement.
• A consistent difference in melanization between alpine and arctic sites was observed, linked to radiative environment differences.

Conclusions:

• Some aspects of phenotypic correlations in Pieris wing melanization are adaptive.
• The study highlights the distinction between character covariation and co-occurrence.
• Results provide insights into biogeographic variation and phenotypic plasticity in butterfly wing patterns.