Beyond species loss: How anthropogenic disturbances drive functional and phylogenetic homogenization of Neotropical dung beetles.

Anthropogenic activities drive tropical forest loss and biodiversity decay. However, few studies have addressed how the biodiversity response varies between disturbance-adapted species (i.e., winners) and those highly susceptible to disturbance (i.e., losers), or whether such responses differ between the taxonomic, functional, or phylogenetic dimensions of diversity. Understanding these dynamics can help prevent or buffer biotic homogenization processes. Using a meta-analytical approach with dung beetles as model organisms, we evaluated how anthropogenic habitat disturbances influence the multiple diversity dimensions of winner and loser species relative to conserved forest sites in the Neotropics. Habitats were organized according to a disturbance gradient ranging from second-growth forests, shaded agroforestry, lowly-shaded agroforestry, living fences, and pastures. Our database included 30 studies, from which we calculated nine metrics divided into three alfa diversity aspects: richness, evenness, and divergence. We also evaluated the beta-diversity response to disturbance and forest protection. All dimensions of dung beetle diversity decreased significantly with increasing disturbance levels, with phylogenetic diversity showing the highest losses, whereas evenness metrics increased in second-growth forests and agroforestry systems. Loser dung beetles showed high diversity loss as well as functional and phylogenetic clustering, reflecting a pervasive biotic homogenization in the most severely disturbed habitats, whereas winner species were insensitive to anthropogenic disturbances. Beta diversity increased significantly with disturbance and forest protection. Our study showed that heavy disturbances erode and homogenized all diversity dimensions of loser dung beetles. However, second-growth forests and agroforestry systems mitigated diversity loss and homogenization processes by favoring the coexistence between functional and phylogenetically distant species and maintaining assemblages compositionally similar to those in conserved forests, highlighting their importance for conservation. We encourage natural resource managers to consider protection of disturbed off-reserve forests in management schemes as these are essential for maintaining biodiversity in an increasingly anthropized world.

Comparative phylogeographic analyses illustrate the complex evolutionary history of threatened cloud forests of northern Mesoamerica.

Comparative phylogeography can elucidate the influence of historical events on current patterns of biodiversity and can identify patterns of co-vicariance among unrelated taxa that span the same geographic areas. Here we analyze temporal and spatial divergence patterns of cloud forest plant and animal species and relate them to the evolutionary history of naturally fragmented cloud forests--among the most threatened vegetation types in northern Mesoamerica. We used comparative phylogeographic analyses to identify patterns of co-vicariance in taxa that share geographic ranges across cloud forest habitats and to elucidate the influence of historical events on current patterns of biodiversity. We document temporal and spatial genetic divergence of 15 species (including seed plants, birds and rodents), and relate them to the evolutionary history of the naturally fragmented cloud forests. We used fossil-calibrated genealogies, coalescent-based divergence time inference, and estimates of gene flow to assess the permeability of putative barriers to gene flow. We also used the hierarchical Approximate Bayesian Computation (HABC) method implemented in the program msBayes to test simultaneous versus non-simultaneous divergence of the cloud forest lineages. Our results show shared phylogeographic breaks that correspond to the Isthmus of Tehuantepec, Los Tuxtlas, and the Chiapas Central Depression, with the Isthmus representing the most frequently shared break among taxa. However, dating analyses suggest that the phylogeographic breaks corresponding to the Isthmus occurred at different times in different taxa. Current divergence patterns are therefore consistent with the hypothesis of broad vicariance across the Isthmus of Tehuantepec derived from different mechanisms operating at different times. This study, coupled with existing data on divergence cloud forest species, indicates that the evolutionary history of contemporary cloud forest lineages is complex and often lineage-specific, and thus difficult to capture in a simple conservation strategy.