Trait distribution in Geometrid moth assemblages does not vary along a western Himalayan elevational gradient

Abstract

AbstractElevation gradients pose challenges for flying insects due to shifts in temperature and air density, impacting their thermoregulation and flight abilities. Understanding how these challenges influence morphological traits across elevational gradients can provide insights into species distribution mechanisms. Geometrid moths, a model group for trait-based analysis among insects, show no significant variation in body size despite declining species diversity along a 1500m elevation span in the western Himalayas. Investigating 697 specimens of 120 Geometrid moth species, I assessed species diversity, turnover, and various traits related to body size and flight capabilities. Results indicate decreasing species diversity and increasing turnover with elevation. Although body length, wing loading, and maneuverability decrease with elevation, intraspecific variability remains insignificant, and trait overlap is high across elevations, suggesting no significant trait partitioning and niche differentiation among species. This supports the argument that species with similar ecological roles persist through turnover, maintaining consistency in trait values across assemblages. These findings align with previous inconsistencies in trait-environment relationships along elevational gradients in Geometrid moths, spanning neotropical and temperate regions. Additionally, the study reiterates the importance of multivariate trait-based approaches in understanding species responses to environmental changes within diverse clades, overcoming taxonomic challenges.