Genetic diversity of Brazilian Pantaneiro horse and relationships among horse breeds

Abstract

-The objective of this work was to evaluate the genetic diversity of Brazilian Pantaneiro horse by microsatellite markers, investigate the effect of genetic bottlenecks and estimate genetic differentiation among four horse breeds. Genetic variation was estimated through allele frequencies and mean breed heterozygosity. Nei´s genetic distances among the breeds Pantaneiro, Thoroughbred, Arabian, Spanish Pure Breed (Andalusian), and Uruguay Creole were calculated, and it was used to construct an UPGMA dendrogram. Clustering at different K values was calculated to infer population structure and assign individuals to populations. Nei´s distances showed a minimum distance between Pantaneiro horse and Spanish Pure Breed (0.228), and similar distances from Spanish Pure Breed to Thoroughbred and to Arabian (0.355 and 0.332). It was observed a great level of diversity, clear distance from Pantaneiro horse to other breeds, and genetic uniformity within breed. It was verified a certain level of substructure of Pantaneiro horse showing no influences from the other studied breeds.Index terms: Equus caballus, animal conservation, molecular markers, microsatellites, genetic resources conservation. Diversidade genética do cavalo Pantaneiro e relações com outras raças de eqüinosResumo -O objetivo deste trabalho foi avaliar a variabilidade genética do cavalo Pantaneiro, por meio de marcadores microssatélites, investigar o efeito genético de "bottlenecks" e estimar a variação genética entre quatro raças de cavalo. A diversidade genética foi estimada por meio da freqüência de alelos e da média de heterozigosidade por raças. A distância genética de Nei foi calculada para as raças Pantaneiro, Puro Sangue Inglês, Árabe, Puro Sangue Espanhol e Crioulo Uruguaio. O agrupamento em diferentes valores de K foi calculado para inferir a estrutura da população e determinar indivíduos às populações. A distância de Nei mostrou distância mínima entre o cavalo Pantaneiro e o Puro Sangue Espanhol (0,228), e entre o Puro Sangue Espanhol e o Puro Sangue Inglês e o Árabe (0,355 e 0,332, respectivamente). Foi observada grande diversidade genética dentro da raça Pantaneiro, evidente distância desta raça em relação às demais raças estudadas, e uniformidade genética dentro da raça. Verificou-se certo nível de subestruturação no cavalo Pantaneiro, sem demonstrar influência das outras raças estudadas.

Genetic analysis of the Venezuelan Criollo horse

“…It was difficult to assign the Venezuelan Criollo horses to a single cluster, as was observed for the Appaloosa and Hanoverian horses (Plante et al, 2007), indicating that these horses are highly variable. A similar result was also obtained in studies of Franches-Montagnes (Glowatzki-Mullis et al, 2006), Sable Island horses (Plante et al, 2007), the Pantaneiro breed (Sereno et al, 2008), and a large set of breeds raised in France (Leroy et al, 2009). In recent studies of human populations, the most difficult regions to detect population structure were the ones that had the smallest between-population variance, while the isolated and relatively homogeneous groups could be efficiently detected, even if the time since the populations diverged was short (Rosenberg et al, 2002;Wang et al, 2007).…”

“…Although there are no historical data confirming the introduction of Barb horses in America, the authors proposed that Spanish Pure Breds were repeatedly crossbred in Spain with different breeds during the XVI-XVIII centuries, and the present-day Barb (as they stayed relatively free of crossbreeding) is more similar to the oldtype Spanish Pure Breds (Kelly et al, 2002). Similarly, genetic analysis of the Pantaneiro horse showed clear genetic differentiation between the Pantaneiro and the Uruguayan Criollo horse despite close geographical location (Sereno et al, 2008). When Venezuelan Criollo horses are separated into three subpopulations from the States of Apure, Merida and Aragua, they cluster within the same branch and show no differentiation.…”

Genetic relationship between the Nordestino horse and national and international horse breeds

“…The average allelic diversity within the remnant Nordestino populations was similar to that observed in other horse breeds from Brazil and around the world (Sereno et al, 2008;Cothran et al, 2011;Conant et al, 2012;Silva et al 2012), in which similar microsatellite markers were used. High genetic diversity was observed in the remnant population of the Nordestino horse studied here, according to estimates of genetic composition (Table 1).…”

Major inconsistencies of inferred population genetic structure estimated in a large set of domestic horse breeds using microsatellites

“…Most studies of horses that have utilized STRUCTURE have examined a small number of breeds, often from a specific geographic locality (Barcaccia et al, 2013; Berber et al, 2014; Bömcke, Gengler, & Cothran, 2011; Conant et al, 2012; Cothran et al, 2011; Galov et al, 2013; Janova et al, 2013; Khanshour, Conant, et al, 2013; Khanshour et al, 2015; Koban et al, 2012; Kusza et al, 2013; Lopes et al, 2015; Mackowski, Mucha, Cholewinski, & Cieslak, 2015; Mujica, 2006; Pablo Gómez et al, 2017; Pires et al, 2016; Prystupa, Juras, Cothran, Buchanan, & Plante, 2012; Rendo, Iriondo, Manzano, & Estonba, 2012; Sereno, Sereno, Vega‐Pla, Kelly, & Bermejo, 2008; Tozaki et al, 2003; Uzans, Lucas, McLeod, & Frasier, 2015). The ∆ K obtained in these studies appeared reasonable for the number of breeds.…”