Some Typical High Altitude Insects and Other Arthropoda

Abstract

While the insect life of the forest and the prairie at lower elevations is remarkable for its enormous diversity, exceedingly few orders have successfully colonized the biome above the upper limits of the forest on high mountains. The dominant high altitude insects belong to groups like Plecoptera, Coleoptera, Lepidoptera, Diptera and Collembola, which also occur at the highest elevations in the vicinity of snow and ice. Some other orders like the Ephemerida, Orthoptera, Dermaptera, Heteroptera, Hymenoptera, Trichoptera and Thysanura usually occupy a minor place among the insects at extreme high altitudes and most of these groups do not also occur much above the limits of the forest. Even in the typically mountain autochthonous groups, there is an abrupt fall in the general abundance of species at the upper limits of the forest. Some of these orders, relatively insignificant at the sea-level, become conspicuously dominant at high elevations. In all cases, the high altitude species are wholly different from those with which we are familiar in the plains. Broadly speaking, the high altitude insects belong to the following ecological groups: 1. Widely distributed eurytype hypsophiles, characteristic of the forest and prairie and abundant at lower elevations, but occurring regularly in the subalpine and sometimes even in the alpine zones on high mountains in different parts of the world. 2. Mountain autochthonous hypsobionts; these exist at the highest elevations and are as a rule never found within the forest zone. Some of them are generally characteristic of all or nearly all the principal mountains of the world. Others are, however, restricted to specific regions only. 3. Lowland and forest elements that occur accidentally above the upper limits of the forest on mountains, but do not breed at high elevations. This chapter aims at an outline of the taxonomy of the dominant hypsobiont types, found on the principal mountains of the world. Mention is also made of some unique forms which are exclusively characteristic of well known mountains.