Aim We analysed the effects of grazing on the diversity and structure of dung beetle communities to see whether the biogeographical and ecological contexts influence dung beetle responses. We hypothesized that the responses of dung beetle communities are modulated by both the ecological conditions resulting from the transformation of native vegetation into grazing areas, and the history of the species inhabiting different biogeographical provinces. Location The state of Hidalgo, in the Mexican Transition Zone, central Mexico. Methods We used a standardized hierarchical sampling procedure in three biogeographical provinces located in Hidalgo. Within each province, we identified the dominant vegetation types, and within these we identified the sites with native vegetation and those modified by grazing. The design included 800 baited pitfall traps, and allowed us to study the response of dung beetle communities with different biogeographical histories to ecological context. Results We captured 8707 beetles belonging to 37 species and 17 genera in the subfamily Scarabaeinae. We found that grazing areas only had a negative effect on dung beetle diversity in tropical forest; conversely, in dry environments (pine–oak forest and xerophilous scrubland) diversity in grazing areas was higher than in the native vegetation sites. We did not detect a clear effect in cloud forest sites. Species turnover between the native vegetation and pastures was high locally, and low over larger spatial scales (vegetation type or biogeographical province). In all four vegetation types grazing was associated with differences in dung beetle community composition. Main conclusions The impact of grazing on dung beetle diversity is dependent to a considerable degree on the local ecological conditions and the biogeographical context that has shaped the composition of communities over time.

Background and aims – A linear morphometric analysis of three taxa of the Tillandsia erubescens complex, composed of T. erubescens var. arroyoensis, T. erubescens var. erubescens, and T. erubescens var. patentibracteata, is presented to evaluate their circumscription. Additionally, their taxonomic rank as varieties or species is discussed considering the obtained results. Geographic distribution, the influence of climate, elevation, and geographic distance on morphological differences between the taxonomic entities is explored.Material and methods – Of a total of 110 herbarium specimens reviewed, 44 were measured. These were previously identified as T. erubescens var. arroyoensis, T. erubescens var. erubescens, or T. erubescens var. patentibracteata. Factor and cluster analyses were performed using 16 quantitative morphological characters. The resulting groups were considered as taxonomic entities supported by morphometric characters, and species distributions were plotted against Mexican biogeographic provinces. A single Mantel test was performed to evaluate the correlation between morphology and climatic variables, elevation, and geographic distance.Key results – The specimens referred to as T. erubescens var. arroyoensis were separated morphometrically from the other two varieties. The most important characters to differentiate T. erubescens var. arroyoensis from T. erubescens var. erubescens were total size, width and length of the leaf sheath and leaf blade, and the number of flowers. The non-overlapping geographical distribution of T. erubescens var. arroyoensis and T. erubescens var. erubescens supports their recognition as independent taxonomic entities. Our study did not support the separation between T. erubescens var. erubescens and T. erubescens var. patentibracteata, which is also reflected by their overlapping geographic distributions. Both precipitation and geographic distance were correlated with the morphological differences among the species.Conclusion – Our morphometric and geographical distribution study supports the recognition of T. arroyoensis and T. erubescens as different species, while no evidence was found to maintain T. erubescens var. erubescens and T. erubescens var. patentibracteata as different taxonomic entities. We provide a set of morphological characters that can be used to distinguish between T. arroyoensis and T. erubescens, including the leaf sheath and leaf blade width, and the number of flowers. Morphological characters agree with the geographic distribution of the studied taxa.

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