Ancient DNA confirms crossbreeding of domestic South American camelids in two pre-conquest archaeological sites

Abstract

The llama (Lama glama) and the alpaca (Vicugna pacos) are important domesticated species, endemic to South America. South American camelids helped ensure the success of humans in the Andes, much like the horse in Europe. Two wild South American camelids, the guanaco and the vicuña have been proposed as the ancestors of these domestic forms. Some scientists have hypothesized that crossbreeding started after the Spanish conquest in the 1500's, since before this event, indigenous people are thought to have kept both domestic breeding lines separate. In an effort to avoid the confounding effects of crossbreeding, ancient DNA from pre-conquest South American camelids was analysed from sites in Bolivia and Ecuador. Our mitochondrial pre-conquest results for Cerro Narrío in Ecuador show that all ancient samples which do not naturally occur in this region and were likely domesticated camelids, had maternal guanaco ancestry. At the Bolivian site of Iwawi, near Lake Titicaca, matrilineal ancestry from both wild species contributed to the domestic forms. These results help disentangle the complex ancestry of the domestic South American camelids and inform future breeding strategies. Additionally confirm the occurrence of crossbreeding between camelids pre-Spanish conquest.