Lama pacos (Linnaeus, 1758)
The alpaca (Lama pacos) is somewhat similar in appearance to the guanaco and llama, but significantly smaller at around 55 to 65 kg, with body hairs up to 500 mm long. The alpaca was apparently domesticated in Peru thousands of years ago, having been selectively bred for its fine wool, which still has great commercial value. (Nowak 1991 and references therein)
The alpaca is one of four South American camelids (mammals in the camel family) recognized today, two of which are wild species, the guanaco (Lama guanicoe) and the vicuña (Vicugna vicugna), and two of which are domesticated forms, the alpaca (Lama pacos) and the llama (Lama glama). Wild vicuña and guanaco diverged from a shared ancestor two to three million years ago. (Wheeler 1995). At one time it was widely believed that both the alpaca and the llama were derived from guanacos. However, in light of new archaeozoological evidence from 6000 to 7000 years ago in the central Peruvian Andes linking alpaca origins to the vicuña, Kadwell et al. (2001) investigated the origins of these domesticated forms using mitochondrial and nuclear DNA markers. Their results supported the hypothesis that the alpaca is derived from the vicuña (and confirmed the hypothesis that the llama is derived from the guanaco), although this work also revealed genetic evidence of historical hybridization and gene flow (at least among domesticated forms). Chromosomal analyses have also indicated that the llama was derived from the guanaco and the alpaca from the vicuña (Marín et al. 2007). Given the well established divergence between the guanaco and vicuña, many authors suggest that the correct name for the alpaca is therefore Vicugna pacos (Kadwell et al. 2001; Marín et al. 2007).
Like the vicuña, the alpaca is strictly a grazer (the guanaco and llama both graze and browse) (Nowak 1991 and references therein).