Data from: Diversity increases with elevation: empidine dance flies (Diptera, Empididae) challenge a predominant pattern

Tropical mountain forests are important reservoirs of biodiversity. They are usually species rich and often support endemic species making them prime targets for conservation effort. The aim of this study is to investigate elevational patterns of species diversity and phenology in order to provide a meaningful understanding of insects' spatio-temporal distributions along a tropical gradient of elevation. Our study focuses on the Empidinae communities (Diptera, Empididae) from Doi Inthanon (north Thailand, gradient 400–2556 m.a.s.l), sampled during two entire years (2006–2007, 2014). This group of insects is more diverse in temperate localities than in the tropics and we found that (1) increase in altitude and latitude has a similar effect, so that the diversity of our model increases with elevation, (2) the phenology is strongly influenced by seasonality with a peak of diversity occurring during the transition between the dry and rainy seasons, (3) there is no phenological shift in the diversity peak with elevations, (4) the species composition changes along the altitudinal gradient and through the year (high beta diversity). The increase of diversity with increasing elevation and the peak of diversity occuring at the transitional period both strongly coincide with abiotic factors, the decreasing temperature and the arrival of the monsoon, respectively.

热带山地森林是重要的生物多样性储库。该类生境通常物种丰富度极高，且多孕育特有物种，因此成为生物多样性保护工作的核心优先目标。本研究旨在探究物种多样性与物候的海拔分布格局，以深入解析昆虫沿热带海拔梯度的时空分布规律。本研究聚焦于泰国北部因他暖山（Doi Inthanon）的舞虻亚科（Empidinae）类群，该类群隶属于双翅目（Diptera）舞虻科（Empididae），采样海拔梯度为400–2556 m.a.s.l，覆盖两个完整年度的采样工作：2006–2007年与2014年。相较于热带区域，该类昆虫在温带生境中具有更高的物种丰富度。本研究得到如下结论：① 海拔升高与纬度升高具有相似的调控效应，本研究模型显示物种多样性随海拔上升而升高；② 物候节律强烈受季节变化影响，物种多样性峰值出现在旱季与雨季的过渡时段；③ 多样性峰值的物候并未随海拔梯度发生偏移；④ 物种组成沿海拔梯度与年度时间轴均发生显著变化，即存在较高的β多样性（beta diversity）。物种多样性随海拔升高而上升的规律，以及多样性峰值出现在过渡时段的现象，分别与非生物因子——气温下降与季风到来——高度吻合。