So close, so far away: analysis of surnames in a town of twins (Cándido Godoi, Brazil)

Candido God ˆ oi is a small Brazilian town known for high rates of twin birth. In 2011, a genetic study showed that ´ this localized high rate of twin births could be explained by a genetic founder effect. Here we used isonymic analysis and surname distribution to identify population subgroups within 5316 inhabitants and 665 different surnames. Four clusters were constructed based on different twin rates (P < 0.001; MRPP test). Fisher´s α and consanguinity index showed low and high values, respectively, corresponding with observed values in isolated communities with high levels of genetic drift. Values of A and B estimators confirmed population isolation. Three boundaries were identified with Monmonier´s maximum difference algorithm (P = 0.007). Inside the isolated sections, surnames of different geographic origins, language, and religion were represented. With an adequate statistical methodology, surname analyses provided a close approximation of historic and socioeconomic background at the moment of colony settlement. In this context, the maintenance of social and cultural practices had strong implications for the population´s structure leading to drift processes in this small town, supporting the previous genetic study.Fil: de Oliveira, Marcelo Zagonel . Universidade Federal Do Rio Grande Do Sul; Brasil. Instituto Nacional de Genetica Médica Populacional; BrasilFil: Faccini, Lavínia Schüler . Universidade Federal Do Rio Grande Do Sul; Brasil. Instituto Nacional de Genetica Médica Populacional; BrasilFil: Demarchi, Dario. Universidad Nacional de Cordoba. Facultad de Filosofia y Humanidades. Museo de Antropologia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto de Antropología de Córdoba; ArgentinaFil: Alfaro, Emma L.. Universidad Nacional de Jujuy. Instituto de Biologia de la Altura; ArgentinaFil: Dipierri, José E.. Universidad Nacional de Jujuy. Instituto de Biologia de la Altura; ArgentinaFil: Veronez, Mauricio R.. Universidade Do Vale Do Rio Dos Sinos; BrasilFil: Cassel, Marlise Colling . Instituto Nacional de Genetica Médica Populacional; Brasil. Universidade Federal do Rio Grande do Sul; BrasilFil: Ribeiro, Alice Tagliani. Universidade Federal Do Rio Grande Do Sul; Brasil. Instituto Nacional de Genetica Médica Populacional; BrasilFil: Matte, Ursula Silveira. Hospital de Clínicas de Porto Alegre; Brasil. Instituto Nacional de Genetica Médica Populacional; BrasilFil: Ramallo, Virginia. Universidade Federal Do Rio Grande Do Sul; Brasil. Instituto Nacional de Genetica Médica Populacional; Brasil. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin