Modificação dos habitats naturais e interações entre formigas e plantas em áreas de cerrado do Norte de Minas

Abstract

The anthropic modification of natural habitats can affect ecological interactions, modifying the structure of ecological networks. In addition to reducing the abundance of species and/or ecological interactions within networks, which in turn depends on the ecological and evolutionary characteristics of the interacting species. In this sense, the objective of this work was to study the diversity of interactions between ants and plants in Cerrado areas under different levels of habitat modification. Thus, we tested the hypothesis that habitat modification in Cerrado areas influences the diversity and structure of interactions between ants and plants. Our expectation was that habitat modification would decrease the richness and abundance of ants, and harm specialist species and favor generalists, with this the network structure tends to be more generalized in more anthropized environments. The study was carried out in 16 areas of cerrado sensu stricto in the northern region of the state of Minas Gerais. Areas were selected that are characterized by remnants of natural vegetation located in regions with different types of land use, namely urban areas, peri-urban areas, rural areas and wild areas. For the sampling of plants in each of the sampling areas, five plots of 100 m² (10 x 10m) were established, totaling 80 plots in the 16 areas. The sampling of ants in each of the areas was carried out in two collections, one in the dry period and the other in the rainy period in the years 2018, 2019 and 2020. In each plot, for all the demarcated plants, three branches were selected and 10 beats were performed in each one, where all the ants present were collected by the beating method, using the modified beating cloth. The collected specimens were conditioned in 70% alcohol, in containers duly identified with information on the area, plot and plant from which they were collected. The samples were sent to the Laboratory of Ecological Interactions and Biodiversity and to the Laboratory of Microscopy at UNIMONTES for sorting and identification. For each area, a network was built considering all species of plants and ants sampled, totaling 16 ant-plant networks. The ant-plant interaction networks were represented by 1,856 ant individuals, distributed in 16 genera and 81 species (morphospecies) and 578 plant individuals, distributed in 107 species. The most abundant plant species were Myracrodruon urundeuva (N= 46), followed by Qualea grandiflora (N= 36) individuals, but 35 plant species had only one individual each. As for ants, the most important genera were Camponotus with 24 species, with emphasis on Camponotus sp. 1 which was the most abundant species of the genus with 108 individuals, and Crematogaster with 16 species, especially Crematogaster sp.1 which was the most abundant in the study (N=370). Corroborating our expectation, the richness and abundance of ants were greater in networks of wild habitats than in networks of other types of habitats. In addition, species composition differed between environments, with wild and urban habitats having the most distinct ant communities. In terms of network structure, the results show that wild habitat networks were larger and less modular than the others. On the other hand, networks from periurban environments were less connected and had low nesting when compared to networks from other types of environments. The results of the present study indicate that the alteration of natural habitats affects both species diversity and the structure of ant-plant interactions in Cerrado areas.