Local and regional drivers of ant communities in forest-grassland ecotones in South Brazil: A taxonomic and phylogenetic approach

Abstract

Understanding biological community distribution patterns and their drivers across different scales is one of the major goals of community ecology in a rapidly changing world. Considering natural forest-grassland ecotones distributed over the south Brazilian region we investigated how ant communities are assembled locally, i.e. considering different habitats, and regionally, i.e. considering different physiographic regions. We used taxonomic and phylogenetic approaches to investigate diversity patterns and search for environmental/spatial drivers at each scale. We sampled ants using honey and tuna baits in forest and grassland habitats, in ecotones distributed at nine sites in Rio Grande do Sul state, Brazil. Overall, we found 85 ant species belonging to 23 genera and six subfamilies. At the local scale, we found forests and grasslands as equivalent in ant species and evolutionary history diversities, but considerably different in terms of species composition. In forests, the soil surface air temperature predicts foraging ant diversity. In grasslands, while the height of herbaceous vegetation reduces ant diversity, treelet density from forest expansion processes clearly increases it. At a regional scale, we did not find models that sufficiently explained ant taxonomic and phylogenetic diversity based on regional environmental variables. The variance in species composition, but not in evolutionary histories, across physiographic regions is driven by space and historical processes. Our findings unveil important aspects of ant community ecology in natural transition systems, indicating environmental filtering as an important process structuring the communities at the local scale, but mostly spatial processes acting at the regional scale.

Long-term ecological research in southern Brazil grasslands: Effects of grazing exclusion and deferred grazing on plant and arthropod communities

“…In the absence of disturbance, such species may dominate, homogenize, and ultimately change the structure of large patches via competitive exclusion [17,18], and these effects may be detected in different spatial components of diversity [12,19]. In productive systems such as a large portion of South America grasslands (specifically, the Río de la Plata grasslands [20]), grazing actually maintains the levels of biodiversity indicators (in comparison with the absence or severe reduction of grazing), for example plant species richness [18] and ant species richness [21].…”

Ants of the Palouse Prairie: diversity and species composition in an endangered grassland

“…In fact, there were five or fewer publications for all the ant species collected besides the common “tramp species” or urban pests, like Tapinoma sessile and Tetramorium immigrans ( Kamura et al 2007 , Uno et al 2010 ). Our systematic review of ant biodiversity surveys in different biomes over the last five years revealed a bias towards Tropical & Subtropical Grasslands, Savannahs & Shrublands (eight studies, Cross et al 2016 , Van Schalkwyk et al 2019 , Arcoverde et al 2016 , Lasmar et al 2020 , Dröse et al 2019 , Hlongwane et al 2019 , de Queiroz et al 2020 , Santoandré et al 2019 ). We found two studies on Tropical & Subtropical Moist Broadleaf Forests ( Lawes et al 2017 , Klunk et al 2018 ), one study on Tropical & Subtropical Coniferous Forests ( Cuautle et al 2016 ), three studies on Temperate Broadleaf & Mixed Forests ( Braschler and Baur 2016 , Helms et al 2020 , Heuss et al 2019 ), one study on Montaine Grasslands & Shrublands ( Jamison et al 2016 ), three studies on Mediterranean Forests, Woodlands & Scrub ( Adams et al 2018 , Catarinue et al 2018 , Flores et al 2018 ) and one study on Deserts & Xeric Shrublands ( Álvarez and Ojeda 2019 ).…”

Additions to the taxonomy of Pheidole (Hymenoptera: Formicidae) from the southern grasslands of Brazil

“…The specimens examined here were obtained from different published and ongoing surveys carried out in the natural grasslands of South Brazil (Dröse et al, 2017;Franco & Feitosa 2018;Dröse et al, 2019;Martins et al, 2020) and sent for identification and/or deposit in the Coleção Entomológica Padre Jesus Santiago Moure of the Universidade Federal do Paraná (DZUP). Also, to improve our species delimitation hypotheses and examine type-specimens, we have visited some of the most representative ant collections for Pheidole in the New World, including the Museu de Zoologia da Universidade de São Paulo, the myrmecological collection of the Centro de Pesquisas do Cacau in Bahia, and the Museum of Comparative Zoology of the Harvard University, Cambridge.…”

“…The last project, developed by the research group of the Laboratório de Ecologia de Interações of Universidade Federal do Rio Grande do Sul (UFRGS), investigated how ant communities are locally assembled in natural forest-grassland ecotones distributed over the south Brazilian region (Dröse et al, 2017(Dröse et al, , 2019. In this project, a total of six natural grassland areas under traditional cattle grazing in the state of Rio Grande do Sul were sampled.…”

“…The taxonomic synopsis of the Pheidole species in Brazilian southern grasslands includes new species and species with revived status, and also the previously published records for this region (Diehl et al, 2005;Pinheiro et al, 2010;Rosado et al, 2012;Dröse et al, 2017;Franco & Feitosa, 2018;Dröse et al, 2019, Martins et al, 2020see Figs. 13-18).…”