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

RODOLFO CARRARA; VIOLETA A. SILVESTRO; GERMÁN H. CHELI; M. FLORENCIA FERNÁNDEZ CAMPÓN AND GUSTAVO E. FLORES

Ciudad de Mendoza

Simposio; Fourth International Tenebrionoidea Symposium; 2015

CONICET

Scotobius pilularius Germar occurs in both natural and human modified areas within humid coastal and grassland environments of Argentina, Brazil and Uruguay (i.e., natural distribution area). However, in Argentina it is also found in very different environments, some of these climatically extreme, such as arid steppes. In these habitats, S. pilularius is found outside natural habitats and in areas associated with different levels of human activity. In this work, we examine factors that may determine the observed spatial distributions of S. pilularius in its natural distribution area and recognize to what extent those factors are responsible of its distribution in distinct habitats of Argentina. We consider that at least three hypotheses can be postulated to explain these distributions: i) climatic conditions determine species occurrences; thus, species is distributed in these habitats because climate allows its subsistence; ii) there is an interplay between climatic conditions and human influence; thus, the species is distributed in areas in which climate allows its subsistence and human activities also promote conditions to its subsistence; and iii) human influence determines its distribution; thus, human activities create conditions to its subsistence which are independent of climatic conditions. Considering spatial information on climate, human influence and distribution localities of S. pilularius, we assessed the support of data to these competing hypotheses by using species distribution models. We found that, while within the natural distribution area of S. pilularius the climate and human influence hypothesis (ii) significantly explain its distribution; only the human influence hypothesis (iii) significantly explains its distribution in extreme habitats of Argentina. This outcome suggests that S. pilularius probably moved from asynanthropy or an independence of human activities before human settlement, to a hemisynanthropy by inhabiting surroundings of human settlements within its natural areas, to conclude in eusynanthropy or a strong dependence of human activity to its subsistence outside of its natural area.