Revista Chilena de Historia Natural 77 (2): 243-250, 2004
RESEARCH ARTICLE
Molecular diversity among domestic guinea-pigs (Cavia porcellus) and their close
phylogenetic relationship with the Andean wild species Cavia tschudii
To investigate the origin and diversity of domestic guinea-pigs Cavia porcellus
(Linnaeus, 1758; Rodentia, Caviidae), we sequenced the mitochondrial cytochrome b gene of 12 domestic and 10 wild
specimens from six species, including the two presumed as ancestral to the domestic one: Cavia tschudii and
Cavia aperea. All maximum parsimony and maximum likelihood analyses grouped C. porcellus with C.
tschudii (mean K2P distance = 3.2 %); best trees had 609 steps (CI = 0.796; Bremer support Index (SI) = 28), and a –Ln =
4419.52, with 100 % and 97 % bootstrap support respectively. This clade, supported by three substitutions and 96 % bootstrap, is also
obtained in the cladistics analysis of corresponding amino acids. When the C. aperea node was forced to join
C. porcellus, these trees were consistently longer, less likely and robust, and with less defining characters than the
optimal one. All C. porcellus sequences also clustered in a node defined by 15 substitutions. The sub-node containing
animals from city markets, pet shops and laboratories was characterized by four substitutions (one non-silent, SI = 7, and 91 %
bootstrap). Some South American C. porcellus, called “criollos” (creoles) by local breeders, were more
diverse. Probably, a particular clade from southern Peru and Chile may represent a pre-Columbian lineage. Mean K2P distance
between C. tschudii and C. aperea was rather large, 7.7 %. Cavia appeared as a robust node
(100 % bootstrap). These results indicate that C. tschudii is the species most closely related to C.
porcellus.
Key words:
Andes, Caviidae,
cytochrome b, domestication, guinea pig, molecular phylogeny
