Changes in the core species of the ant-plant network of oak forest converted to grassland: replacement of its ant functional groups

Abstract

Land-use change in terrestrial environments is one of the main threats to biodiversity. The study of ant-plant networks has increased our knowledge of the diversity of interactions and structure of these communities; however, little is known about how land-use change affects ant-plant networks. Here we determine whether the change in land use, from native oak forest to induced grassland, affected the network properties of ant-plant networks in a temperate forest in Mexico. We hypothesize that the disturbed vegetation will be more nested and generalized due to the addition of generalist species to the network. The oak forest network comprises 47 plant species and 11 ant species, while the induced grassland network has 35 and 13, respectively. Floral nectar was the resource used most intensely by the ants in both vegetation types. The ant-plant network of the induced grassland was significantly more nested and generalist than that of the oak forest; however, none of the networks were nested when considering the frequency of interaction. In both vegetation types, the ants were more specialized than the plants, and niche overlap was low. This could be related to the dominant species present in each type of vegetation: Prenolepis imparis in the oak forest and Camponotus rubrithorax in the grassland. The central core of cold climate ant species in the oak forest was replaced by a central core of subordinate Camponotini and tropical specialists in the induced grassland. These results suggest that the increase in nestedness and generalization in the grassland may be related to the loss of the cold climate specialists from the core of the oak forest network. Our findings provide evidence that land-use change increases the level of generalization in the ant-plant interaction networks of temperate forests.

Habitat simplification affects functional group structure along with taxonomic and phylogenetic diversity of temperate‐zone ant assemblages over a ten‐year period

“…According to our hypothesis 1, we expected a higher species diversity in the induced grassland because the microclimatic conditions of higher temperature and lower humidity in the modified habitat (induced grassland) would facilitate the presence of a wide assortment of generalist ( P. tepicana , P. obtusospinosa and Monomorium ebenium ) and opportunistic ( Dorymyrmex insanus and D. pyramicus ) species, as observed in the results. Furthermore, as a result of ecological succession and the accompanying higher plant diversity, induced grasslands may present greater availability of plant‐associated resources for ants, such as extrafloral or floral nectaries, or hemipteran honeydew (Cuautle et al 2022), which would also favor higher ant diversity in that habitat type. It remains to be determined to what degree these differences in evenness might be associated with changes in the interactions between ant species.…”