Outer bounds: forest edges emulate vertical strata as a habitat filter for butterfly assemblages.

Understanding the patterns that arise from habitat filtering processes,
whether natural or human-induced, is a crucial step in developing
strategies for maintaining biodiversity. Tropical forests provide unique
habitat conditions in vertical and horizontal dimensions, which
consequently affect the composition of local assemblages. In this study,
we examined the effect of forest fragmentation and vertical stratification
on the phylogenetic and functional diversity of Atlantic Forest butterfly
assemblages. We hypothesized that fragmentation positively selects
butterfly lineages that are more tolerant to exposed habitats. Likewise,
forest canopies would converge to a similar filtering effect since they
represent a strong filter for the forest-dwelling species. We analyzed two
distinct datasets separately and compared their effects through
phylogenetic and functional approaches. We did not detect the effect of
fragmentation on species composition, but it has affected lineages
composition indirectly via functional traits. Forest vertical structure
affected the butterfly assemblage composition, and we detected a
phylogenetic signal at the community level, which implies a filtering of
butterfly lineages. Phylogenetic diversity substantially decreased from
understory to canopy. Butterfly assemblages from fragmented areas and
canopies converged to lower body sizes and thorax volumes and presented
lower functional diversity. Our results suggest that forest fragmentation
and vertical strata have similar filtering effects on species and trait
composition of assemblages. It also implies that human-induced processes
represent a major threat to tropical butterfly diversity, especially for
the lineages that inhabit the understory and continuous forests. The
current dataset contains:  Species composition matrices from
previously published studies: (Uehara-Prado et al. 2007) and (Santos et
al. 2017) Species functional traits matrices