Thursday, 23 October 2014

Origins of the laboratory guinea pig

Newborn guinea pigs (Cavia porcellus)
(c) Per Svendsen
The domestication of guinea pigs dates back hundreds of years. Animals raised for food or the laboratory are of a species (Cavia porcellus) that is not found in the wild. Its closest relatives are the Brazilian guinea pig (C. aperea) and the montane guinea pig (C. tschudii) from western South America including Peru.

Analysis of mitochondrial DNA (here and here) clearly shows that the domestic guinea pig groups with the montane species. Furthermore, analysis of the skeletons of mummified guinea pigs from archaeological sites in Southern Peru and Northern Chile (here) indicates that domestication started in the Andes, the natural habitat of C. tschudii.

Karyotypes of Cavia tschudii male (left) and C. porcellus female (right)
From Walker et al. 2014 (here) (c) Laura I. Walker et al.
A recent paper (here) compared the chromosomes of the wild and domestic species and confirmed that differences arose in the course of this first phase of domestication.

Guinea pigs were imported by European traders in the 16th Century and underwent a second phase of domestication that resulted in the laboratory guinea pig. There was even a further phase of domestication in South America with two lineages of guinea pigs selected for improved meat quality.

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