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

CARRARA RODOLFO; SILVESTRO VIOLETA; CHELI GERMÁN H.; FERNÁNDEZ CAMPÓN F; FLORES GUSTAVO E.

Mendoza

Simposio; IV International Symposium on Tenebrionoidea; 2015

CCT MENDOZA-CONICET

Scotobiuspilularius Germar occurs in both natural and human modified areaswithin humid coastal and grassland environments of Argentina,Brazil and Uruguay (i.e.,natural distribution area). However, in Argentina it is also found in verydifferent environments, some of these climatically extreme, such as aridsteppes. In these habitats, S. pilularius is found outside naturalhabitats and in areas associated with different levels of human activity. Inthis work, we examine factors that may determine the observed spatialdistributions of S. pilularius in its natural distribution area andrecognize to what extent those factors are responsible of its distribution indistinct habitats of Argentina.We consider that at least three hypotheses can be postulated to explain thesedistributions: i) climatic conditions determine species occurrences; thus,species is distributed in these habitats because climate allows itssubsistence; ii) there is an interplay between climatic conditions and humaninfluence; thus, the species is distributed in areas in which climate allowsits 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.pilularius the climate and human influence hypothesis (ii) significantlyexplain its distribution; only the human influence hypothesis (iii)significantly explains its distribution in extreme habitats of Argentina. Thisoutcome suggests that S. pilularius probably moved from asynanthropy oran independence of human activities before human settlement, to ahemisynanthropy by inhabiting surroundings of human settlements within itsnatural areas, to conclude in eusynanthropy or a strong dependence of humanactivity to its subsistence outside of its natural area.