The biomechanics and functional diversity of flight

摘要

Insect presence on the earth is ancient, persistent and ubiquitous. Following the initial evolution of wings either in the late Devonian or early Carboniferous, pterygote insects rapidly diversified to become, by the mid- to late Carboniferous, a predominant feature of the terrestrial biota. This role has been retained to the present time, and today pterygote insects can be found in essentially all terrestrial ecosystems and on all continental land masses. The contemporary taxonomic richness of insects is famously high, with the number of described pterygote species exceeding 1 million, and the number of as yet undescribed species ranging potentially as high as 10 million. Among the arthropods, perhaps only mite diversity rivals that of the winged insects (Hammond, 1992; Walter and Behan-Pelletier, 1999), and much of mite species richness may derive from symbiotic associations with insects. Pterygotes today are major consumers of plant productivity and also serve as a nutritional resource for diverse arthropod and vertebrate taxa. A rough indication of the trophic influence exerted by insects is suggested by an estimate for their aggregate biomass. Approximately 10~(18) insects may be alive worldwide at any given time (Williams, 1960). Assuming an average body mass of 1 mg, this number of individuals corresponds to an approximate biomass of 10~(12) kg, a value roughly comparable to the total mass of the contemporary human population (Dudley, 2000). To this day, winged insects thus compete with humans at the level of primary trophic consumption.