Disentangle the effect of climate and human influence on distribution patterns of Scotobius pilularius Germar (Coleoptera: Tenebrionidae)

CARRARA, R., V.A. SILVESTRO, G.H. CHELI, M.F. FERNÁNDEZ CAMPÓN Y G.E. FLORES

Mendoza

Simposio; IV International Tenebrionoidea Symposium; 2015

Scotobius pilularius Germar occurs in both natural and humanmodified areas within humid coastal and grassland environments of Argentina,Brazil and Uruguay (i.e., natural distribution area). However, in Argentina itis also found in very different environments, some of these climaticallyextreme, such as arid steppes. In these habitats, S. pilularius is found outside natural habitats and in areasassociated with different levels of human activity. In this work, we examinefactors that may determine the observed spatial distributions of S.pilularius in its natural distribution area and recognize to what extentthose factors are responsible of its distribution in distinct habitats ofArgentina. We consider that at least three hypotheses can be postulatedto explain these distributions: i) climatic conditions determine speciesoccurrences; thus, species is distributed in these habitats because climateallows its subsistence; ii) there is an interplay between climatic conditionsand human influence; thus, the species is distributed in areas in which climateallows its subsistence and human activities also promote conditions to itssubsistence; and iii) human influence determines its distribution; thus, humanactivities create conditions to its subsistence which are independent ofclimatic conditions. Considering spatial information on climate, humaninfluence and distribution localities of S. pilularius, we assessed thesupport of data to these competing hypotheses by using species distributionmodels. We found that, while within the natural distribution area of S. pilulariusthe climate and human influence hypothesis (ii) significantly explain itsdistribution; only the human influence hypothesis (iii) significantly explainsits distribution in extreme habitats of Argentina. This outcome suggests that S.pilularius probably moved from asynanthropy or an independence of humanactivities before human settlement, to a hemisynanthropy by inhabitingsurroundings of human settlements within its natural areas, to conclude ineusynanthropy or a strong dependence of human activity to its subsistenceoutside of its natural area.