New insights into the evolution of clonality and its implications on southern range expansion in native populations of the little fire ant? L. Chifflet, L. A. Calcaterra & V. A. Confalonieri

L. A. CALCATERRA ; V. A. CONFALONIERI; L. CHIFFLET

Curitiba, Paraná, Brazil

Simposio; XXIII Simposio de Mirmecología, an International Ant Meeting; 2017

Universidade Federal do Paraná, Curitiba, Paraná, Brazil

NEW INSIGHTS INTO THE EVOLUTION OF CLONALITY AND ITS IMPLICATIONS ON SOUTH-ERN RANGE EXPANSION IN NATIVE POPULATIONS OF THE LITTLE FIRE ANT L. CHIFFLET1, L. A. CALCATERRA2& V. A. CONFALONIERI1 1Grupo de Investigación de Filogenias Moleculares y Filogeografía, Instituto de Ecología, Genética y Evolución, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (CONICET-UBA), Intendente Güiraldes 2160 (C1428EGA), Ciudad Universitaria,Ciudad Autónoma de Buenos Aires, Argentina, email: lu_chifflet@hotmail.com, 2Fundación para el Estudio de Especies Invasivas (FuEDEI), Bolívar 1559 (B1686EFA) Hurlingham, Buenos Aires, Argentina The little fire ant, Wasmannia auropunctata, is native from the Neotropics and has become invasive outside its native range. Its original distribution extended from Mexico to northern Argentina, although new evidence suggests a recent southern range expansion during the last 50 years presumably medi-ated by human activity, reaching central Argentina. In addition, this ant species can form supercolo-nies and exhibits a polymorphism in its reproductive system, in which queens and males of popula-tions established in anthropic habitats are mostly produced clonally, while those in natural environ-ments (e.g. primary forests) mostly reproduce sexually. Given that all the populations within the south-ernmost limit of native distribution of W. auropunctata are established in anthropic habitats, we evalu-ated if clonality is associated to the recent southern range expansion. We amplified 12 microsatelite loci by PCR multiplex from a total of 194 reproductive individuals (185 queens/gynes and 9 males) from 101 nests in 37 sites with different degree of disturbance (i.e. primary forests, floodplains and human disturbed habitats) in southern South America (i.e. Argentina, Bolivia, Paraguay, Uruguay and southern Brazil). We inferred the reproductive system of each site/population using GeneClone v.2.0. We added to our dataset 17 populations from northern South America analysed by Foucaud et al. (2009), having a final dataset of 54 populations. Clonality was the most common reproductive system, occurring in 38 of 54 sites, mostly in human disturbed habitats. In these populations, all the females or males of different nests within the same supercolony were genetically identical. All the populations present along the recently colonized area were clonal, suggesting an association between clonality and the southern range expansion of the little fire ant during the last 50 years. Floodplains contained, almost at the same frequency, either sexual populations or populations where the reproductive individ-uals within the same nest were genetically identical (clonal), but different from the ones of neighbour-ing nests of the same supercolony, suggesting sexual reproduction events. We called the latter ?mixed reproductive system?. Within primary forests, most populations were sexual. Because flooding is known to represent an important selective pressure, and a variety of ant species have evolved several responses to it, the high frequency of mixed reproductive system in this kind of habitat could constitute valuable evidence of the origin of clonality during the evolutionary history of the little fire ant.(CONICET, ANPCYT, USDA-ARS).