Climate and plant structure determine the spatiotemporal butterfly distribution in a tropical mountain

In Serra do Cipó (Minas Gerais, Brazil), seven elevations were selected as sampling units along the western slope of Serra do Cipó ranging approximately from 800 to 1400 m, and separated by at least 2 km. Three transects (about 500 m apart) with four Van-Someren Rydon (VSR) traps were marked at each elevation to attract fruit-feeding butterflies. At each transect, the four traps were separated by about 50 m, baited with fermented banana with sugar cane juice . The data for each transect per period is a set of four days sampling with four traps. There were eight periods of sampling in two years. The diversity parameters calculated were: i) abundance (number of individuals per elevation), ii) gamma diversity (the accumulation of species richness by elevation – γ diversity), (iii) alpha diversity (average species richness by elevation – α diversity), and (iv) spatial and temporal beta diversity (variation of the species composition - β-diversity, obtained through the formula β = γ / αmean, according to Wittaker, 1972). The abiotic variables (humidity, precipitation, and temperature) were obtained from meteorological towers (Onset HOBO® U30 data-logger) arranged adjacent to the transects of each sampling elevation. So the butterfly diversity parameters were accumulated per elevation per sampling period. The vegetation was obtained in the paper of Motta et al. 2018, that were done in the same elevation area. For the vegetation analysis the butterfly diversity parameters were accumulated only per elevation.

本研究在巴西米纳斯吉拉斯州的锡波山（Serra do Cipó）沿其西坡选取7个海拔梯度作为采样单元，海拔范围约800~1400 m，各采样单元间间距不小于2 km。每个海拔梯度布设3条样带（样带间距约500 m），每条样带设置4台范-索伦-赖登诱捕器（Van-Someren Rydon, VSR）以吸引食果蝴蝶。单条样带内的4台诱捕器间距约50 m，诱饵为掺有甘蔗汁的发酵香蕉。每个采样周期内，单条样带的采样数据为4台诱捕器连续4天的采样结果。整个研究在2年内共开展8个采样周期。本次计算的多样性参数包括：① 多度（abundance，即单个海拔梯度的个体总数）；② γ多样性（Gamma diversity，按海拔梯度累加的物种丰富度）；③ α多样性（Alpha diversity，单个海拔梯度的平均物种丰富度）；④ 时空β多样性（Beta diversity，即物种组成的变异，依据Wittaker 1972年提出的公式β=γ/α_mean计算得到）。非生物变量（湿度、降水量与气温）通过布设在各采样海拔样带附近的气象塔（Onset HOBO® U30数据记录仪）获取。因此，蝴蝶多样性参数按每个采样周期与对应海拔梯度进行累加汇总。植被数据取自Motta等人2018年的研究，该研究的采样区域与本次研究的海拔范围一致。针对植被分析的需求，蝴蝶多样性参数仅按海拔梯度进行累加汇总。