Woolly ancestry

Natural History, June, 2002 by Stephan Reebs

Few animals are better emblems of South America than the quartet formed by the llama, the alpaca, the vicuna, and the guanaco. Both the llama and the alpaca are domesticated forms long believed to be descended from the guanaco, a wild camelid. But a new genetic analysis, done by Miranda Kadwell, of the Institute of Zoology in London, and colleagues from both Great Britain and South America, suggests that the alpaca may be more closely related to the vicuna, also a wild species.

As much as go percent of South America's native domestic livestock was lost during the century following the Spanish conquest. Since then, alpacas and llamas have been extensively hybridized. To make sense of the consequently complex genetic picture, the researchers combined a number of DNA markers. Analysis of mitochondrial DNA, which is inherited only from the mother, supported the traditional view of a guanaco-alpaca lineage. However, several other genetic markers--ones that are passed along by both the mother and the father, and thus may give a more reliable and complete picture of the hybridization history--pointed to the vicuna as the probable ancestor of the alpaca.

Untangling the history of these animals would be of more than purely academic interest. Both the domesticated alpaca and the wild vicuna are exploited for their fleece, Unprocessed vicuna fleece is extremely fine and can fetch about $200 a pound, making it the most expensive natural fiber in the world and an important source of income for rural people. By contrast, after years of alpaca-llama hybridization, the fleece of alpacas has lost its fineness and sells for less than $10 a pound. If the alpaca is indeed a descendant of the vicuna, geneticists might be able to identify pure-bred alpacas and guide new breeding programs to improve the quality of alpaca fleece. ("Genetic Analysis Reveals the Wild Ancestors of the Llama and the Alpaca," Proceedings of the Royal Society of London B 268, 2001)

Stephan Reebs is a professor of biology at the Universite de Moncton in New Brunswick, Canada, and the author of' Fish Behavior in the Aquarium and in the Wild (Cornell University Press).