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ID: 750 In: Journal of zoological systematics and evolutionary research, Vol. 54, no. 3 (Aug. 2016), p.182-188. Summary: AbstractThis study tries to unveil the contribution of climatic shift in shaping the extreme body size diversity in terrestrial isopods (Oniscidea). Trying to explain size variation at an interspecific level, we test five hypotheses: (1) Bergmann's Rule and the temperature‐size rule postulate large size in cold areas (2) The metabolic cold adaptation theory postulates small animal sizes in cold environments (3) The primary productivity hypothesis predicts size increase in resource‐rich areas (4) The aridity resistance hypothesis predicts large size in arid regions and (5). The acidosis hypothesis predicts smaller size with decreasing soil pH. Globally, Bergmann's rule and the aridity hypothesis are weakly supported. Among families and genera, results are variable and idiosyncratic. Conglobating species sizes provide weak support for the acidosis hypothesis. Overall, size is strongly affected by familial affiliation. Isopod size evolution seems to be mainly affected by phylogenetically constrained life‐history traits.AbstractDistributions of 738 species of terrestrial isopods (Crustacea: Oniscidea) against a global map of soil moisture. The medium sizedChaetophiloscia cellaria(Dollfus, 1884), Philosciidae (top), inhabits humid habitats whereas the the large‐sizedHemilepistus reaumurii(Milne‐Edwards, 1840), Agnaridae (bottom), lives in desert habitats. This exemplifies the tendency of isopods to increase in size with decreasing moisture which we have found characterizes the clade globally. Overall within‐taxa relationships are weak and idiosyncratic. Isopod size evolution mainly reflect phylogenetically constrained life history.