Fiedler Konrad, Brehm Gunnar
Department of Botany & Biodiversity Research, University of Vienna, Rennweg 14, 1030 Vienna, Austria.
Institut für Zoologie und Evolutionsforschung mit Phyletischem Museum, Friedrich-Schiller Universität Jena, 07743 Jena, Germany.
Insects. 2021 Oct 3;12(10):903. doi: 10.3390/insects12100903.
On tropical mountains, predation pressure decreases with elevation. Accordingly, one expects an elevational decay in the prevalence of costly defensive traits such as aposematic coloration. Using light-trap catches of Arctiinae moths (353 species, 4466 individuals), assembled along a forested gradient in the megadiverse tropical Andes of southern Ecuador, we show that the incidence of aposematic coloration decreases strongly between 1040 and 2670 m asl. While over 60% of Arctiinae moths were warningly colored at lowest sites, this fraction decreased to less than 20% in montane forest, yet increased slightly again at the highest sites in the very open forest. In parallel, the incidence of hymenopteran mimics and of species that mimic chemically defended beetles decreased with elevation. Hymenopteran mimics accounted for less than 5% of Arctiinae moths at sites above 2100 m, and beetle mimics were essentially lacking at high elevations. These patterns coincide with a change in gross taxonomic composition of Arctiinae ensembles and with an increase in average body size towards higher elevations. Representatives of Euchromiina and Ctenuchina became scarce with altitude, whereas the prevalence of Lithosiinae increased. Our findings suggest that the variable selective pressures along the elevational gradient favor warning coloration primarily at lower sites, whereas cryptic appearance of adult moths dominates in the tropical upper montane forest.
在热带山区，捕食压力随海拔升高而降低。因此，人们预期诸如警戒色等代价高昂的防御性状的流行程度会随海拔升高而下降。我们利用在厄瓜多尔南部生物多样性丰富的热带安第斯山脉沿森林梯度收集的灯诱夜蛾科蛾类（353种，4466只个体），发现警戒色的发生率在海拔1040米至2670米之间大幅下降。在最低海拔处，超过60%的夜蛾科蛾类具有警戒色，但在山地森林中这一比例降至不到20%，而在非常开阔的森林中的最高海拔处又略有上升。与此同时，膜翅目拟态者以及拟态具化学防御能力甲虫的物种的发生率也随海拔升高而下降。在海拔2100米以上的地点，膜翅目拟态者占夜蛾科蛾类的比例不到5%，而在高海拔地区基本没有甲虫拟态者。这些模式与夜蛾科类群的总体分类组成变化以及平均体型随海拔升高而增大相吻合。优灯蛾亚科和栉灯蛾亚科的代表物种随海拔升高而变得稀少，而锂灯蛾亚科的发生率则增加。我们的研究结果表明，沿海拔梯度变化的选择压力主要在较低海拔处有利于警戒色，而在热带高海拔山地森林中，成年蛾类的隐蔽外观占主导地位。
