DOI: 10.5061/dryad.mcvdnck4g
title: Data for: Aridity and chronic anthropogenic disturbance as organizing forces of fruit-feeding butterfly assemblages in a Caatinga dry forest

description: Anthropogenic disturbances and climate change are expected to reorganize
 biodiversity on multiple ecological levels from populations to ecosystems,
 especially in arid and semiarid regions due to environmental filtering
 imposed by water stress. This paper examines the individual and combined
 effects of chronic anthropogenic disturbance and increased aridity on the
 structure of fruit-feeding butterfly assemblages in a human-modified
 landscape of Caatinga dry forest, in the northeast of Brazil. Butterflies
 were recorded monthly across old-growth forest stands and their
 assemblages were described in terms of taxonomic and functional
 community-level attributes confronted with different levels of chronic
 disturbance and aridity. Butterfly assemblages were species-poor but had
 high species replacement (turnover) along both the chronic disturbance and
 aridity gradients. We observed a negative effect of aridity on the alpha
 and beta diversity of butterfly assemblages. Butterfly assemblages across
 forest stands exposed to high levels of chronic disturbance and aridity
 had a nested structure. Functional diversity (Rao’s Q) and the
 community-weighted means (CWM) of ocellus-bearing species and
 monocot-feeding larvae were negatively and positively affected by
 increased aridity and chronic disturbance, respectively. Our findings
 suggest that aridity and its combination with chronic disturbance have a
 drastic effect on the structure of butterfly assemblages in the Caatinga
 dry forest. These findings highlight that rainfall and chronic
 disturbances as major drivers of biological reorganization in
 human-modified landscapes. As aridity increases, Caatinga tends to support
 taxonomically and functionally impoverished and highly distorted
 assemblages.
description: Sampling of fruit-feeding
 butterflies was carried out monthly from May 2018 to April 2019. Each plot
 had one sampling unit composed of five portable bait traps, totaling 45
 traps across our study landscape. The traps were arranged a distance of at
 least 30 m from each other and suspended at a height of between 1 and 1.5
 m above the ground. The traps remained open during seven consecutive days
 per month and were checked every 48 hours, when baits were replaced. The
 number of trap-days was considered the sampling effort, i.e., the total
 number of traps used in the field (45 traps) multiplied by the number of
 days sampling lasted (84 days), which result in 3,780
 trap-days. The traps used were of the Van Someren-Rydon
 type (following DeVries,
 1997), which consist of
 cylindrical tubes made with netting (110 cm high × 35 cm in diameter) and
 an internal cone (30 cm high and 22 cm wide at the opening) at the bottom
 to prevent butterflies from escaping. The lower part was open and attached
 to a plywood platform with a distance of 4 cm to allow butterflies to
 enter the trap. A mixture of banana and sugar cane juice fermented for 48
 h was used as bait. Baits were placed inside traps in plastic pots with a
 perforated cover to prevent butterflies from drowning in the liquid, to
 avoid feeding by other insects, and to reduce evaporation (Freitas et al.,
 2014; Hughes et al., 1998). During each visit, all captured individuals were
 identified, marked, and then released. Voucher specimens of all recorded
 species (up to 10 vouchers per species — about 1% of the number of
 individuals total sampled) were deposited in the entomological collections
 of the Universidade Federal de Pernambuco, Recife, PE, Brazil. All
 butterflies were identified to the specific level and the higher
 classification followed Lamas (2004), modified after Wahlberg et al.
 (2009).
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