Microclimate and vegetation structure significantly affect the composition and phenology of butterfly assemblages in an Ecuadorian dry forest

Butterflies are segregated at the microhabitat level with microclimate being an essential factor affecting butterfly species. However, few studies have analyzed the distribution of multi-species assemblages of butterflies across microhabitat dimensions other than height, and examined which microhabitat factors mainly affect their composition in the Neotropics. Here, we studied the structure and composition of butterfly assemblages in ridgetop and valley microhabitats over seasons and examined which microhabitat components most affect them. The study was carried out from June 2009 to May 2010 at the Lalo Loor Dry Forest Reserve in western Ecuador, a highly threatened habitat with notable levels of endemism. Two transects were established, one in each microhabitat, where traps with rotten shrimp or fermented banana were located in the understorey and canopy to record butterfly species distribution and abundance. Humidity and temperature were recorded during the sampling period and vegetation variables in each microhabitat were measured. A total of 3731 individuals and 93 species were collected. Higher species richness and abundances were registered during the wet season. Butterfly assemblages from ridgetop and valley significantly differed during the dry season and were more similar during the wet season. Linear regression models and Canonical Correspondence Analysis revealed microclimatic variables and vegetation structure (vegetation density, average tree diameter and/or canopy cover) were significant predictors of the composition and abundance of butterfly assemblages. A differential distribution of taxonomic groups in the microclimatic and vegetation structure gradients of the CCA was also found. The tight relationship between butterfly assemblages and microclimate suggests global climate change might significantly affect dry forest butterfly faunas.