From past to present: Shifting landscape drivers of dung beetle functional and phylogenetic diversity in a tropical reserve

Understanding biodiversity responses to temporal changes in landscape structure is crucial for forecasting shifts in species composition and ecosystem functioning, as well as improving conservation strategies in protected areas. This study evaluates how the functional and phylogenetic diversity of dung beetles has responded to landscape changes over two time periods, 1999-2000 and 2016-2017, in the Los Tuxtlas Biosphere Reserve, Mexico. Dung beetles were collected from ten tropical forest fragments and five pastures. Forest cover increased by 19.7 % and the number of fragments decreased by 48 %, suggesting partial landscape re-aggregation. The functional dispersion of dung beetle assemblages increased significantly in pastures, while remaining stable in forest habitats. Phylogenetic diversity, particularly the mean nearest taxon distance, was consistently higher in pastures than in forests across both periods. Temporal shifts in landscape drivers were observed: the diversity of past forest assemblages was best explained by landscape composition, whereas the diversity of present forest assemblages was more influenced by spatial configuration. In both periods, phylogenetic diversity was mainly driven by landscape heterogeneity and forest cover. Our findings demonstrate that biodiversity responses to landscape attributes vary across dimensions and time, underscoring the importance of long-term studies. Maintaining forest cover and connectivity is crucial for preventing functional and phylogenetic homogenization. These results reaffirm the central role of native forests in conserving tropical biodiversity.