Increase in tracheal investment with beetle size supports hypothesis of oxygen limitation on insect gigantism.

ABSTRACT: Recent studies have suggested that Paleozoic hyperoxia enabled animal gigantism, and the subsequent hypoxia drove a reduction in animal size. This evolutionary hypothesis depends on the argument that gas exchange in many invertebrates and skin-breathing vertebrates becomes compromised at large sizes because of distance effects on diffusion. In contrast to vertebrates, which use respiratory and circulatory systems in series, gas exchange in insects is almost exclusively determined by the tracheal system, providing a particularly suitable model to investigate possible limitations of oxygen delivery on size. In this study, we used synchrotron x-ray phase-contrast imaging to visualize the tracheal system and quantify its dimensions in four species of darkling beetles varying in mass by 3 order

SUBMITTER: Kaiser A 

PROVIDER: S-EPMC1941816 | biostudies-literature | 2007 Aug

REPOSITORIES: biostudies-literature