Consistent Trait Patterns in a Hyper Diverse Moth Clade Along a Western Himalayan Elevational Gradient

Elevation gradients pose significant challenges for flying insects due to temperature and air density shifts, which affect thermoregulation, flight abilities, and distribution patterns. Geometrid moths serve as a useful model for studying these traits. This study investigates how trait patterns in geometrid moth assemblages change across a 1500-m elevational gradient in the western Himalayas; 697 specimens from 120 geometrid moth species were examined to assess species diversity, turnover, and traits related to body size and flight capabilities. The results show a decline in species diversity with increasing elevation, accompanied by consistent turnover from low to high elevations. However, elevation did not significantly influence morphological traits such as body size (thermal sensitivity) or flight traits like wing loading and maneuverability at the assemblage level. There was high overlap in the trait spaces, thereby showing no significant trait-space differentiation among individuals across elevations. This possibly suggests that, despite species turnover within assemblages, those with similar ecological roles maintain consistent trait values, contributing to stability in the assemblage-level trait structure. This study reveals how species traits and assemblage-level trait distributions vary across an elevational gradient. The overall trait structure remained largely stable across elevations, potentially reflecting abiotic filtering, though direct environmental evidence is lacking. Further, this emphasizes the value of trait-based approaches to understanding species' responses to environmental changes, especially in paleotropical ecosystems.