• Elevational richness patterns of sphingid moths support area effects over climatic drivers in a near‐global analysis

      Bärtschi, F; McCain, CM; Ballesteros‐Mejia, L; Kitching, I; Beerli, N; Beck, J (Wiley, 2019-03-03)
      Aim We test hypotheses on the environmental control of elevational richness patterns of sphingid moths for their global applicability and generality. Specifically, we compare effects of area with climate‐related drivers, such as primary productivity and temperature, while also considering direct effects of precipitation. Major taxa Sphingid moths (Lepidoptera). Location Eighty‐six mountain ranges of the Old World and the Australia/Pacific region, from Scandinavia and Siberia through the African and Australasian tropics to South Africa and Southern Australia. Methods We used a large compilation of point locality records for 744 species, in addition to fine‐grained range maps derived from species distribution modelling of these records, to characterize the elevational pattern of species richness in 86 custom‐delineated mountain regions. For both types of data, we compared the effects of environmental drivers on richness by comparing standardized coefficients of multivariate models for pooled data after accounting for between‐region variation in richness. Results We observed varying patterns of elevational richness across the research region, with a higher prevalence of midpeaks in arid regions. We found overwhelming support for area as a main determinant of richness, modulated by temperature and productivity, whereas we detected no effect of precipitation. Main conclusions Area, productivity and temperature are the main environmental predictors explaining a large proportion of variability in sphingid richness. This is consistent not only with other elevational studies, but also with empirical and theoretical biodiversity research in a non‐elevational context (with the caveat of some unresolved issues in elevational area effects). However, distinct differences in elevational patterns remain even within the same mountain ranges when comparing with other Lepidoptera, that is, geometrid moths, which highlights the importance of understanding higher clade differentiation in ecological responses, within insects and in other groups.