Genetic diversity and population structure in Brazilian Mangalarga Marchador horses

ABSTRACT. One hundred and fifteen unrelated Mangalarga Marchador horses were sampled from three geographically distinct regions of Minas Gerais State, Brazil (South, Southeast, and Northeast) and tested for 10 microsatellite loci. Genetic diversity and population structure param-eters were estimated with ARLEQUIN 3.0, CERVUS 2.0, POPGENE 1.31, GENEPOP on the web, STRUCTURE 2.0, and SPAGEDI 1.2 software packages. Under Hardy-Weinberg assumptions, seven markers were at equilibrium (LEX014, LEX017, LEX019, SGCV23, TKY321, VHL20, and VIASH39), while two (ASB3 and LEX031) presented significant homozygote excess. Seventy-four alleles were identified in these nine markers, with a mean of 8.22 alleles. Mean heterozygosity was 0.637 and polymorphism information content was 0.662. Markers ASB3, LEX019, SGCV23, TKY321, and VHL20 were highly informa-tive (PIC>0.7) and may be useful for eventual expansion of parentage test panels. The F ST value (0.0562) indicated relatively little geographi-cal structure. However, based on a Bayesian-based cluster analysis un-der a three-cluster model, 94 % of the 115 individuals were correctly assigned to the subpopulations from where they were sampled. Mea