Year: 2022

"GIANT INSECTS, with wingspans as large as 70 cm, ruled the Carboniferous and Permian skies. Here we show, using a dataset of more than 10,500 fossil insect wing lengths, that size tracked atmospheric oxygen concentrations only for the first 150 Myr of insect evolution." https://lnkd.in/dEANyiE View in LinkedIn

INFLEXIBLE PLUMBING SYSTEM. "Unlike many other ectotherms, in insects, gas exchange takes place through a system of tubes, the tracheae, that lead directly to the cells of the mitochondria, where oxygen acts as an electron receptor during respiration. The exceptionally high power demands of insect flight, coupled with this gas exchange system, led early physiologists to conclude that large modern flying species may be at their performance limits." https://lnkd.in/dcXHB7K View in LinkedIn

PLUMBING LIMITATIONS. "Why are insects small? In the Paleozoic Era, atmospheric oxygen levels peaked significantly higher than the current level. Along with this oxygen peak came giant insects, many times larger than those currently observed. This suggests that oxygen transport may inhibit insects from becoming giants." https://lnkd.in/dVziXg3 View in LinkedIn

SCALING OXYGEN TRANSPORT. "If this were the case, then one would expect to observe an increase of investment in gas exchange structures in larger insects, i.e. hypermetric scaling. This has been observed in tenebrionid beetle trachea." https://lnkd.in/dVziXg3 View in LinkedIn

THE OXYGEN FACTOR. "All global giants are aerobically active animals, not gentle giants with low metabolic demands. Oxygen concentration in the atmosphere correlates with gigantism in the Paleozoic but not thereafter, likely because of the elaboration of efficient gas-exchange systems in clades containing giants." https://lnkd.in/dv_ZqB3 View in LinkedIn

PLANT IMPACT ON INSECTS. "Moreover, plant activities appear to have caused rates of evolution in terrestrial animals to accelerate. Late Palaeozoic insect and tetrapod faunas diversified together with terrestrial plants, and enhanced burial of organic carbon raised global oxygen levels, fuelling a spectacular radiation of insect gigantism." https://lnkd.in/dBS9JZw View in LinkedIn

HYPEROXYGENATED PERIOD. "Because metabolic oxygen demand increases with increasing body size, environmental oxygen concentration (pO2) is frequently invoked as an important constraint on the size of animals. Giant late Paleozoic insects, with wingspans as large as 70 cm, are the iconic example of the oxygen-body size link; hyperoxic conditions during the Carboniferous and Permian are thought to have permitted the spectacular sizes of the largest insects ever." https://lnkd.in/dEANyiE View in LinkedIn

RELATIONSHIP OF SIZE AND O2. "The data are best explained by a model relating maximum size to atmospheric environmental oxygen concentration (pO2) until the end of the Jurassic, and then at constant sizes, independent of oxygen fluctuations, during the Cretaceous and, at a smaller size, the Cenozoic. Maximum insect size decreased even as atmospheric pO2 rose in the Early Cretaceous following the evolution and radiation of early birds, particularly as birds acquired adaptations that allowed more agile flight." https://lnkd.in/dEANyiE View in LinkedIn

UNCOUPLING AND INCREASED INTERACTIONS. "A further decrease in maximum size during the Cenozoic may relate to the evolution of bats, the Cretaceous mass extinction, or further specialization of flying birds. The decoupling of insect size and atmospheric pO2 coincident with the radiation of birds suggests that biotic interactions, such as predation and competition, superseded oxygen as the most important constraint on maximum body size of the largest insects." https://lnkd.in/dEANyiE View in LinkedIn

AREA TO VOLUME LIMITATIONS. "Flying insects should be particularly susceptible to variations in atmospheric pO2 because their flight musculature has high energy demands, particularly during periods of active flight. The volume occupied by tracheae, tubes that transport oxygen throughout the body, scales hypermetrically with body volume, imposing further surface area-to-volume constraints on maximum size." https://lnkd.in/dEANyiE View in LinkedIn