Criollo goats of the Americas: an Iberian herd left to five centuries of local selection
The goats the Spanish landed in the sixteenth century were never bred back to a standard, and the populations that came out the other end are now the animal of the driest, poorest ground in Latin America. Microsatellite work across 43 goat populations places the Ecuadorian criollo with the Iberian and Creole cluster with no detectable crossing to modern commercial breeds; genome-wide work in Peru finds low inbreeding, regional structure — and effective population sizes that are falling.
Why this wins its question: The corpus and the general literature both cover the cattle, the pigs, the sheep and the horses Spain landed in the Americas; the goat, which ended up on the worst ground of all and is the animal of the dry forest and the Andean steppe smallholder, is the one that gets left out. This object gives it the same treatment: the 43-population comparison that places the Ecuadorian criollo in the Iberian-Creole cluster and shows the Canary and African breeds sitting apart from it, the actual diversity figures, the negative result that no commercial breed has been crossed into it, and the first genome-wide Peruvian survey — with the declining effective population sizes and the absence of any formal breed recognition stated in the same breath, and with the sixteenth-century origin marked as inherited from the literature rather than measured.
Claims
Every assertion below is bound to registered sources and carries its own confidence. Weight them; do not treat the page as uniformly authoritative.
The framing both studies work from is that the Creole livestock of the Americas descend from animals carried from the Iberian Peninsula during the colonisation and then left to local conditions. The Ecuadorian study states it directly: the Chusca Lojana "belongs to the genetic group of the American Creoles, descendants of the Iberian populations imported by the Spanish colonizers five centuries ago", and describes the resulting Creole populations as the ones inhabiting "the harshest environments" of the continent.
The Peruvian study names the presumed founding stock and its source, and the naming is secondhand. Peruvian Creole goats were "introduced by Spanish colonizers in the 16th century" and "likely originated from breeds such as the white Celtiberian and the Castilian of Extremadura - referred to by chroniclers of the time as 'Granada,' 'Murcia,' and 'Malaga' types". This is a citation to earlier literature in that paper's introduction, not a result of its own genotyping, and the confidence here reflects that.
The Ecuadorian result rests on 145 animals of the Chusca Lojana typed at 38 microsatellites from the FAO-ISAG panel, set against 43 goat populations from Spain, the American Creoles, Europe and Africa. Within the breed: a mean of 8 alleles per locus, an effective number of 4.3, expected heterozygosity 0.71 against observed 0.63, polymorphic information content 0.67, and an F(IS) of 0.11. Across the 43 populations, F(IS) 0.087, F(IT) 0.176 and F(ST) 0.098.
The clustering separates the Atlantic islands and Africa from the Iberian-Creole group rather than lumping all "old" goats together. At K = 2 the 43 populations split into one cluster holding the European breeds - Spanish, Saanen and Alpine - together with most of the Creole breeds, and a second holding the African and Canary Islands breeds. At K = 5 the Spanish, the Canary Islands and the African breeds separate out; the Chusca Lojana only separates from the other Creole populations at K = 18.
What makes the Ecuadorian population useful as a genetic resource is a negative finding: no introgression from the major international breeds - Saanen, Alpina, Anglo-Nubian, African or Spanish - was detected in the Chusca Lojana, and the four biotypes local practice distinguishes are not supported genetically (F(ST) = 0.0073 between them). The breed is one homogeneous population that has not been crossed out.
Its diversity is high by the standards of its neighbours. The mean and effective allele numbers for the Chusca Lojana are close to those of the Spanish goat of the USA (7.81 and 4.24) and higher than those reported for the Creole goats of Argentina, Bolivia, Brazil, Colombia, Cuba, Peru and Venezuela.
The Peruvian study is the first genome-wide assessment of these populations: 106 animals newly sampled in Ancash, Ica and Lima, merged with a public dataset covering Lambayeque, Tumbes and Piura, for a final 255 individuals and 48,932 SNPs in most analyses. It finds moderate structure, with Ica clearly separated and the northern populations overlapping, runs of homozygosity that are predominantly short, shared regions on chromosome 6, and inbreeding coefficients that are generally low, highest in Ancash.
The cost is in the same paper and belongs beside the rest. Estimates of effective population size show a declining trend across the Peruvian regions, with Piura holding the largest recent size; and the animals are not protected by any formal status, since Peruvian Creole goats "are not officially recognized as a formal breed in Peru". A five-century-old landrace with low inbreeding today is not the same thing as a secure one.
The limits of what these two studies can show. Neither dates the introduction, tests ancient DNA, or samples Iberian founders directly: both genotype living herds and read history off the resulting structure, and the Peruvian paper's Spanish-origin sentence is a literature citation rather than a finding. Neither is a study of the colonial period at all - their stated purpose is conservation and breeding management - so this object takes the sixteenth-century attribution as the working consensus of that literature and not as something demonstrated on these data.