Data for: Aridity and chronic anthropogenic disturbance as organizing forces of fruit-feeding butterfly assemblages in a Caatinga dry forest

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.Excel, WindowsSampling 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)