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Ants are the dominant soil faunal group in many if not most terrestrial ecosystems, and play a key role in soil structure and function. This study documents the impacts of invasion by the exotic cat's claw creeper vine, Macfadyena unguis-cati (L.) Gentry (Bignoniaceae) on surface-situated (epigaeic) and subterranean (hypogaeic) ant communities in subtropical SE Queensland Australia where it is a major environmental weed of riparian areas, rainforest communities and remnant natural vegetation, smothering standing vegetation and causing canopy collapse. Soil ants were sampled in infested and uninfested areas at eight sites spanning both riparian and non-riparian habitats in subtropical SE Queensland. Patterns of ant species composition and functional grouping in response to patch invasion status, landscape type and habitat stratum were investigated using ANOVA and non-metric multidimensional scaling ordination. The epigaeic and subterranean strata supported markedly different ant assemblages, and ant communities also differed between riparian and non-riparian habitats. However, M. unguis-cati invasion had a surprisingly limited impact. There was a tendency for ant abundance and species richness to be lower in infested patches, and overall species composition was different between infested and uninfested patches, but these differences were relatively small, and did not occur consistently across sites. There were changes in functional group composition that conformed to known functional group responses to environmental change, but these were similarly limited and inconsistent across sites. Our study has shown that ant communities are surprisingly resilient to invasion by M. unguis-cati, and serves as a warning against making assumptions about invasion impacts based on visual appearances.

This paper consists of a detailed analysis of how the participants in a debate build their emotional position during the interaction and how such a position is strongly related to the conclusion they defend. In this case study, teenage Mexican, students, arguing about access to drinking water, display extensive discursive work on the emotional tonality given to the issue. Plantin’s (2011) methodological tools are adopted to follow two alternative emotional framings produced by disagreeing students, starting from a common, highly negative, thymic tonality. Through the analysis of four parameters (distance to the problem; causality/agentivity; possibility of control and conformity to the norms) we describe how the emotional dimension of schematization (Grize 1997) is argumentatively relevant. In authentic discourse, it is impossible to separate emotion from reason. The conclusion section discusses the implications for the design of argumentation-based pedagogical activities.