Abstract :
Twenty microsatellite markers were used to investigate genetic diversity and relationships
in the Portuguese Serpentina (SERP) and the Brazilian Moxotó (MOX) goat breeds, which
present a striking resemblance and are believed to have a common origin. A total of 46
animals of the SERP breed were sampled in southern Portugal, and 233 MOX goats were
sampled in five different regions of Northeast Brazil. Genetic diversity was high, with a
mean number of alleles of nearly 8.7 in both breeds, but expected heterozygosity and allelic
richness were higher in SERP. The genetic distance between the two breeds resulted in a
global FST of 0.16, and a strong deficit in within-breed heterozygosity was observed in MOX,
mostly because of population substructuring. The estimated inbreeding was about 0.05 in
SERP and ranged from 0.02 to 0.08 in the different MOX subpopulations. These subpopulations
showed considerable genetic differentiation from each other, and those sampled
in Paraíba and Rio Grande do Norte are the ones with a closer relationship with SERP. The
analysis with STRUCTURE confirmed that some MOX subpopulations may share a common,
but distant, ancestry with SERP, both having contributions from the same potential
ancestral population. Other MOX subpopulations, however, are identified with ancestral
populations distinct from SERP. These analyses further confirmed that, with the exception
of goats from Rio Grande do Norte, the otherMOXsubpopulations show very little evidence
of admixture among them, which may reflect the typical goat raising system in Northeast
Brazil, where herds are usually kept closed and isolated, with little opportunity for gene
flow among subpopulations. Our results indicate that SERP is likely a distant ancestor of
MOX, but founder effects, genetic drift, selection for different environmental constraints
and the possible influence of other breeds in the more recent past, probably lead to a differentiation
of MOX subpopulations from their distant ancestor, as well as from each other
