Species, phylogenetic, and functional diversity of ant (Hymenoptera: Formicidae) communities in a simplified habitat over a ten-year period

There is scarce information on how the biotic and abiotic changes linked to simplification affect several diversity dimensions, such as taxonomic, functional, and phylogenetic diversities. We investigated whether transforming natural oak forests into induced grasslands affected species diversity, functional group structure, and phylogenetic diversity of ant assemblages inhabiting a temperate forest in central Mexico. We placed over 1,000 pitfall traps in five sampling events covering a ten-year period. We used Hill numbers to evaluate species diversity differences between vegetation types. Ant species were classified into stress-related functional groups, which were analyzed for their association with vegetation types and changes to their proportional abundance over time. Our analysis of phylogenetic diversity was based on the standardized effect size of the mean nearest taxon distance. Species richness did not differ between vegetation types, yet grasslands showed greater diversity for the q=1 and q=2 orders. Regarding functional structure, cold climate specialists were associated with oak forests, and generalist species were predominant in induced grasslands. Higher phylogenetic diversity with an overdispersed structure was associated with oak forest, whereas lower phylogenetic diversity and a clustered pattern were found in induced grassland. These results indicate that habitat simplification may not affect the number of ant species, but rather, it changes their relative abundances and reorganizes the functional and phylogenetic structure, particularly shifting toward the dominance of evolutionarily related species and stress-tolerant groups. These results highlight the importance of integrating further dimensions of diversity to properly evaluate the reassembly dynamics after habitat simplification.