Paper wasps are darker at high elevation.

Area of Science:

• Ecology and Evolutionary Biology
• Animal Coloration and Adaptation

Background:

• High-elevation environments present challenges such as colder temperatures and increased UV-B radiation.
• These abiotic factors can significantly impact animal survival and reproduction, driving evolutionary adaptations.
• Body color, particularly melanization, is hypothesized to play a role in thermoregulation and photoprotection for ectotherms.

Purpose of the Study:

• To investigate the adaptive significance of body color variation in the paper wasp Agelaia pallipes along an elevational gradient.
• To test the prediction that ectotherms at higher elevations are darker to enhance heat gain and UV protection.

Main Methods:

• Sampling of 146 paper wasps (Agelaia pallipes) across nine elevations (2,600-3,380 m) in the Colombian Andes using Malaise traps.
• Analysis of body luminance, color patterning, and surface texture (shiny vs. matte) of dry-preserved specimens using digital photography.
• Quantification of color variation across different body parts to assess environmental correlations.

Main Results:

• Significant variation in body luminance, color patterning, and surface texture was observed across different body parts.
• Wasps from higher elevations exhibited darker thoraces, supporting the thermal melanism hypothesis.
• A higher frequency of wasps with matte facial textures was found at high elevations compared to shiny textures.

Conclusions:

• The findings support the thermal melanism hypothesis, suggesting that darker coloration in paper wasps is an adaptation to colder, high-elevation environments.
• Intraspecific color variation, including thoracic darkening and matte facial textures, likely represents an adaptive response to environmental pressures.
• Body color serves as a crucial adaptation for paper wasps inhabiting challenging high-altitude habitats.