Population structure and genetic diversity of Mangalarga Marchador horses

Abstract

Mangalarga Marchador (MM) is the most numerous horse breed in Brazil. The aim of this study was to analyze the genetic structure of the MM horses population of Brazil based on pedigree analysis and identify factors that may affect its genetic variability. Pedigree data from 1906 to 2015 was used and the inbreeding and probability of gene origin parameters were obtained, considering the total population (TP, n = 514,282) and a reference population (RP, n = 172,508) from 2005 to 2015. The generation interval was 10.43 in the TP and 9.48 in the RP. The inbreeding coefficient (F) was 1.02% in the TP and 1.10% in the RP. The effective population size was 1,471 for the TP and 959 for the RP. The effective number of ancestors, founders, and founder genomes were 1,038, 1,062, and 150 in the TP, and 198, 225, and 133 in the RP, respectively. The numbers of founders that exhibit 50% of the current gene pool of the breed represented 7.94% of the total founders of the TP and 19.09% of the RP. The analysis of probability of gene origin alert for a small loss of genetic diversity in the recent population. However, the Mangalarga Marchador population does not exhibit relevant factors that may seriously affect your genetic variability and that would impair the evolution of the breed in Brazil.