Population history and genetic variability of the American Shire horse

Stephens, T.D.; Splan, Rebecca K.

doi:10.1017/s2078633613000052

Cited by 7 publications

(5 citation statements)

References 13 publications

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“…When a population suffers a demographic decrease, such as that experienced by the MH at the beginning of the last century, fe is overestimated by ignoring some genetic bottleneck effects, but the ratio (f e /f a ) allows us to consider the loss of genetic variation promoted by the overuse of few sires. The bottleneck ratio (f e /f a ) in the MH population was 1.89, which is similar to that observed in the Czech-Moravian Belgian horse (1.86), more favorable compared to the Austrian Noriker (4.00) [14] and American Shire (3.65) [17], but lower than that found in the Slovak and Hungarian Hucul horse and the Croatian Posavina, that were 1.6, 1.41 and 1.29, respectively [15,22,37]. The value of the fa/fe ratio in Table 1 indicates a 50% reduction of the genetic diversity as expected by the fact that for the MH current population, the effective founders are 34 and the effective ancestors only 17.…”

Section: Discussionsupporting

confidence: 80%

“…Furthermore, the Maremmano horse breed from Italy [21] was reported to have values for complete and equivalent complete generations very close to those observed in the Murgese. On the other side, for several horse breeds, most of them having a long breeding tradition, such as the Arab [20,41], the Pura Raza Español [10], the Lipizzan [9], the Slovack Hucul [15], the American Shire [17], the Noriker [14] and the Hanoverian warmblood horses [13], deeper pedigrees were reported.…”

Section: Discussionmentioning

confidence: 99%

“…Moreover, demographic analyses may help to understand the factors that have affected the genetic history of a population [9]. In the last years, a number of studies have been carried out on the population structure and genetic variability of horse breeds by analyzing pedigree data [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]. Classically, monitoring of genetic diversity via the use of genealogical information has been carried out by assessing inbreeding (F) and relationships (R) in the population of interest, converted into effective population size (N e ), which is regarded as a good indicator to estimate genetic diversity for conservation purposes.…”

Section: Introductionmentioning

confidence: 99%

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Genetic Variability within the Murgese Horse Breed Inferred from Genealogical Data and Morphometric Measurements

Bramante¹,

Pieragostini

Ciani

2022

Diversity

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The Murgese horse (MH) is a native breed from Apulia (Italy). This study aimed to evaluate the population status with regard to the available pedigree information (6923 animals born between 1900 and 2020), as well as its demographic and morphological evolution. The mean equivalent generations were 5.88. The average relatedness, inbreeding coefficient and increase in inbreeding by equivalent generation (ΔF) were 9.88%, 5.22%, 1.05%, respectively. The effective population size based on ΔF was 47.46. The effective number of founders (fe) was 36, and that of ancestors (fa) was 19. The ratio fe/fa was 1.89 witnessing a bottleneck effect. The ratio fa/fe indicates a 52% reduction of the genetic diversity as expected, given the fact that, for the current population (now recovered to 5000 breeding animals), the fe is 34 and the fa only 17, with 50% of diversity being explained by only six ancestors. Basically, the results reflect a substantial loss of genetic diversity in the MH breed over generations since its official founding, and unbalanced use of sires in the population, highlighting the importance of continuous monitoring and implementation of more effective conservation measures, especially in view of the growing request for boosting genetic improvement for MH morpho-functional traits.

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Section: Discussionsupporting

confidence: 80%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Genetic Variability within the Murgese Horse Breed Inferred from Genealogical Data and Morphometric Measurements

Bramante¹,

Pieragostini

Ciani

2022

Diversity

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“…In the Amiata, Andalusian, Asinina de Miranda and Martina Franca donkeys, the f e /f a ratio is similar (0.85, 1.08, 1.12, 1.22) [6][7][8]10]. The high f e /f a ratio suggests a disproportionate use of some breeding animals, presumably stallions, resulting in a loss of genetic diversity compared with that expected under random mating conditions [55]. The results of the current study did not indicate a bottleneck, so the Littoral-Dinaric donkey and the Istrian donkey populations were stable.…”

Section: Discussionmentioning

confidence: 90%

Genetic and Population Structure of Croatian Local Donkey Breeds

Ivanković

Bittante

Šubara³

et al. 2022

Diversity

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The two native Croatian donkey breeds (Littoral-Dinaric donkey and Istrian donkey) were marginalized in the second half of the 20th century and were on the verge of biological extinction. The aim of this study was to analyze the demographic and genetic status of two donkey breeds, two decades after the start of protection by analyzing their pedigrees and genetic structure. The average generation interval was higher for the Istrian donkey (7.73) than for the Littoral-Dinaric donkey (7.27). The rate of the effective number of founders compared with the effective number of ancestors in the Littoral-Dinaric donkey (1.03; 325/316) and in the Istrian donkey (1.08; 70/65) revealed no evidence of a genetic bottleneck. The inbreeding coefficient (F) and the average relatedness coefficient (AR) was lower in the Littoral-Dinaric donkey population (0.99%; 0.13%) than in the Istrian donkey population (1.77%; 1.10%). Genetic microsatellite analysis showed relatively high genetic diversity in Littoral-Dinaric donkey and Istrian donkey breeds, expressed by mean allele number (5.92; 5.85) and expected heterozygosity (0.650; 0.653). Genetic differentiation between the Littoral-Dinaric donkey and the Istrian donkey has not significantly increased in the last two decades (FST = 0.028). Genetic analysis also showed no evidence of high inbreeding or genetic bottleneck in both breeds. A total of 11 haplotypes including 28 polymorphic sites were found in 30 samples. Analysis of mtDNA has shown that the Littoral-Dinaric donkey and Istrian donkey breeds belong to the Equus asinus africanus group. The study confirms the need to use different analytical approaches to get a regular and complete insight into the situation and trends within and between breeds, so that the existing diversity can be fully preserved.

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“…Food producing animals have been the main targets for conservation actions [ 5 ], but horses, dogs, cats, rabbits that in many countries are primarily used for other purposes are becoming increasingly recognized as of conservation value [ 6 , 7 ]. Countries are reviewing their national domestic animal breeds [ 8 ], and in Sweden the Swedish National Board of Agriculture has identified 63 such breeds historically originating in Sweden, and has declared them of national conservation concern.…”

Section: Introductionmentioning

confidence: 99%

Pedigree data indicate rapid inbreeding and loss of genetic diversity within populations of native, traditional dog breeds of conservation concern

Jansson

Laikre

2018

PLoS ONE

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Increasing concern is directed towards genetic diversity of domestic animal populations because strong selective breeding can rapidly deplete genetic diversity of socio-economically valuable animals. International conservation policy identifies minimizing genetic erosion of domesticated animals as a key biodiversity target. We used breeding records to assess potential indications of inbreeding and loss of founder allelic diversity in 12 native Swedish dog breeds, traditional to the country, ten of which have been identified by authorities as of conservation concern. The pedigrees dated back to the mid-1900, comprising 5–11 generations and 350–66,500 individuals per pedigree. We assessed rates of inbreeding and potential indications of loss of genetic variation by measuring inbreeding coefficients and remaining number of founder alleles at five points in time during 1980–2012. We found average inbreeding coefficients among breeds to double–from an average of 0.03 in 1980 to 0.07 in 2012 –in spite of the majority of breeds being numerically large with pedigrees comprising thousands of individuals indicating that such rapid increase of inbreeding should have been possible to avoid. We also found indications of extensive loss of intra-breed variation; on average 70 percent of founder alleles are lost during 1980–2012. Explicit conservation goals for these breeds were not reflected in pedigree based conservation genetic measures; breeding needs to focus more on retaining genetic variation, and supplementary genomic analyses of these breeds are highly warranted in order to find out the extent to which the trends indicated here are reflected over the genomes of these breeds.

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Population history and genetic variability of the American Shire horse

Cited by 7 publications

References 13 publications

Genetic Variability within the Murgese Horse Breed Inferred from Genealogical Data and Morphometric Measurements

Genetic Variability within the Murgese Horse Breed Inferred from Genealogical Data and Morphometric Measurements

Genetic and Population Structure of Croatian Local Donkey Breeds

Pedigree data indicate rapid inbreeding and loss of genetic diversity within populations of native, traditional dog breeds of conservation concern

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