Effects of body size and lung type on desiccation resistance, hypoxia tolerance and thermal preference in two terrestrial isopods species

Terrestrial isopods have evolved adaptations to reduce water loss, which is necessary for life in low humidity environments. However, the evolution of a waterproofed cuticle prevent loss environment could also impede oxygen uptake from environment. We therefore postulate an evolutionary trade-off between retention and gas exchange this group soil animals. The outcome expected be affected by both differences across species (different types lung) within (body size resulting surface area volume ratios). To test these ideas, we compared two sympatric isopods: Porcellio scaber Oniscus asellus. While P. possesses covered lungs typical drier habitats, O. asellus has simple open respiratory fields are direct contact with external air. For each species, assessed how individuals broad range body differed their hypoxia desiccation tolerance. In addition, thermal preference. found clear effects identity on tolerance humidity. Desiccation resistance was tightly linked rates (R2 = 0.96) strongly resembled interspecific pattern 20 isopod species. our results did not support postulated trade-off. Tolerance covaried, increasing being higher scaber. Thermal preference humidity, but size. Our study increases understanding ecophysiology can useful explaining geographical distribution use microhabitats climate change context.