A database of dung beetle trait values from a transect between the Mediterranean and the Sahara

This database provides average trait measurements for dung beetles surveyed a c. 400 km linear transect following a strong aridity gradient parallel to the Morocco-Algerian border from the semiarid Mediterranean coast in the North towards the hyperarid (i.e. extremely dry) conditions of the Sahara toward the South (see deCastro-Arrazola et al. PeerJ 2018). All morphological traits were measured with a Leica M165C microscope, using Leica Application Suite LAS V4.0 with the Z-builder module to process the images and obtain the measurements. Not all traits could be measured in all 61 species sampled in the study. Adult trophic preferences and dung relocation strategy for feeding purposes (both qualitative traits) were obtained from the literature and expert knowledge. For these categorical traits, values could be assigned with confidence to all species. For continuous traits, we aimed at measuring 10 individuals per species, and finally 80% of species had measures for 5 or more individuals due to the limited numbers of individuals in the samples. The individuals measured for each species were chosen from as many localities as possible to maximise intraspecific trait variation, covering their distribution along the gradient. In total, we measured 23 traits on 347 individuals (mean 5.8 and median 5.0 individuals per species) leading to a total of more than 7000 measurements, complemented with further categorical traits gathered from literature or our own observations in the field.