The loss of biodiversity caused by human activity is assumed to alter ecosystem functioning. However our understanding of the magnitude of the effect of these changes on functional diversity and their impact on the dynamics of ecological processes is still limited. We analyzed the functional diversity of copro-necrophagous beetles under different conditions of land use in three Mexican biosphere reserves. In Montes Azules pastures, forest fragments and continuous rainforest were analyzed, in Los Tuxtlas rainforest fragments of different sizes were analyzed and in Barranca de Metztitlán two types of xerophile scrub with different degrees of disturbance from grazing were analyzed. We assigned dung beetle species to functional groups based on food relocation, beetle size, daily activity period and food preferences, and as measures of functional diversity we used estimates based on multivariate methods. In Montes Azules functional richness was lower in the pastures than in continuous rainforest and rainforest fragments, but fragments and continuous forest include functionally redundant species. In small rainforest fragments (<5 ha) in Los Tuxtlas, dung beetle functional richness was lower than in large rainforest fragments (>20 ha). Functional evenness and functional dispersion did not vary among habitat types or fragment size in these reserves. In contrast, in Metztitlán, functional richness and functional dispersion were different among the vegetation types, but differences were not related to the degree of disturbance by grazing. More redundant species were found in submontane than in crassicaule scrub. For the first time, a decrease in the functional diversity in communities of copro-necrophagous beetles resulting from changes in land use is documented, the potential implications for ecosystem functioning are discussed and a series of variables that could improve the evaluation of functional diversity for this biological group is proposed.

Resumen. El índice de entropía de Shannon y otras medidas de complejidad se utilizan frecuentemente para evaluar la diversidad de especies en comunidades ecológicas, aun cuando su comprensión es difícil y sus valores no son comparables. En este trabajo se muestra que los números efectivos de especies (medidas de diversidad verdadera) permiten obtener una interpretación intuitiva y fácilmente comparable de la diversidad de especies. Se ejemplifica su uso reanalizando los datos de 4 trabajos publicados en la Revista Mexicana de Biodiversidad (realizados en distintos ecosistemas y regiones de México, con distinta resolución taxonómica y enfocados en distintos grupos biológicos). Se utilizan modelos de estimación en los que se considera que las muestras son representaciones incompletas de las comunidades. Se explica también la manera en que las medidas de diversidad de distinto orden incorporan a las especies según su abundancia en la comunidad. Los resultados obtenidos pueden resultar de especial interés cuando los valores de diversidad se utilizan para proponer medidas para el manejo de recursos y la conservación biológica. Palabras clave: diversidad verdadera, especies equivalentes, especies igualmente comunes, índice de Shannon, riqueza, equidad, dominancia, abundancia.

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.