DOI: 10.5061/dryad.60jv067
title: Data from: Moth body size increases with elevation along a complete tropical elevational gradient for two hyperdiverse clades

description: The body size of an animal is probably its most important functional
 trait. For arthropods, environmental drivers of body size variation are
 still poorly documented and understood, especially in tropical regions. We
 use a unique dataset for two species-rich, phylogenetically independent
 moth taxa (Lepidoptera: Geometridae; Arctiinae), collected along an
 extensive tropical elevational gradient in Costa Rica, to investigate the
 correlates and possible causes of body-size variation. We studied 15,047
 specimens (794 species) of Geometridae and 4,167 specimens (308 species)
 of Arctiinae to test the following hypotheses: 1) body size increases with
 decreasing ambient temperature, as predicted by the temperature-size rule;
 2) body size increases with increasing rainfall and primary productivity,
 as predicted from considerations of starvation resistance; and 3) body
 size scales allometrically with wing area, as elevation increases, such
 that wing loading (the ratio of body size to wing area) decreases with
 increasing elevation to compensate for lower air density. To test these
 hypotheses, we examined forewing length as a proxy for body size in
 relation to ambient temperature, rainfall, vegetation index and elevation
 as explanatory variables in linear and polynomial spatial regression
 models. We analysed our data separately for males and females using two
 principal approaches: mean forewing length of species at each site, and
 mean forewing length of complete local assemblages, weighted by abundance.
 Body size consistently increased with elevation in both taxa, both
 approaches, both sexes, and also within species. Temperature was the best
 predictor for this pattern (-0.98 &lt; r &lt; -0.74), whereas body
 size was uncorrelated or weakly correlated with rainfall and enhanced
 vegetation index. Wing loading increased with elevation. Our results
 support the temperature-size rule as an important mechanism for body size
 variation in arthropods along tropical elevational gradients, whereas
 starvation resistance and optimization of flight mechanics seem to be of
 minor importance.
description: Brehm_etal_ecog_03917_Moth_imagesThis zip file contains images of almost all specimens in the study with body weight data (27 species of Arctiinae and 57 species of Geometridae; each a male and a female). Scale bar = 10 mmAppendix_Raw_EVI-dataThis file contains the raw EVI (Enhanced Vegetation Index) data from the studyAppendix_Raw_Female ProportionsThis file contains the raw data for female proportions of Arctiinae and Geometridae moths in the studyAppendix_Raw_FWL-area-massThis file contains the raw data for forewing lengths (FWL), wing area and mass of Arctiinae (27 males and 27 females of 27 species) and Geometridae (57 males and 57 females of 57 species) moths in the studyAppendix_Raw_WinglengthThis file contains the raw data for fore wing lengths (FWL) of all Arctiinae and Geometridae moths in the study.Appendix_HistogramsThis file contains raw data and histograms of Arctiinae and Geometridae moths at 12 sites along the elevational gradient.Appendix_Winglength_subtaxaThis file contains winglength data of subtaxa of Arctiinae and Geometridae.