Minimal stories in Southeast Buenos Aires grasslands: carabid beetle biodiversity throughout an urban-rural gradient

Urbanization modifies the original habitat and the biodiversity. Research throughout urban-rural gradients allows the monitoring of human activities on the biodiversity of native environments. Our aims were to a) record the diversity of edaphic coleopteran families and carabid species in native grassland remnants of urban, suburban and rural areas; b) identify potential taxa exclusively associated with urban and rural sites, respectively, or indifferent to such categorization; and c) compare the body sizes, wing morphology and trophic groups of carabid beetles in the three levels of urbanization. Our results showed that carabid species richness is higher in urban areas, but we found no difference in the number of families of edaphic coleopterans. One species, the eurytopic Argutoridius bonariensis, dominated in all areas; but in the suburban and rural areas it shared the dominance with stenotopic Argutoridius sp. N° 2. Carabid species assemblages did not exactly reflect the urban-rural gradient selected a priori. Regarding size variation, we found that large size species were more abundant in two urban sites; wing-dimorphic and apterous species were more abundant in urban areas. In reference to trophic groups, we recorded larger number of omnivores in the urban areas. We showed that some species can develop and survive in cities while others cannot, creating and sustaining a “new” urban ecosystem, with its own history, rules, dynamics and internal ecological memory.