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Alvarez I.,SERIDA Deva | Fernandez I.,SERIDA Deva | Lorenzo L.,Centro Ecuestre El Asturcon | Payeras L.,AECABMA | And 2 more authors.
Journal of Animal Breeding and Genetics | Year: 2012

Pedigree information and 179 mtDNA sequences from two endangered Spanish horse breeds, the Asturcón pony (143) and the Mallorquí horse (36), were analysed to asses: (i) the pedigree and molecular maternal genetic diversity of the two breeds; (ii) the concordance between the dam lines recorded in the corresponding studbooks and the mtDNA haplotypes identified; and (iii) to assess the losses of maternal genetic variability occurred from the foundation of the studbooks to present. Up to 50 Asturcón and 18 Mallorquí founder dam lines were identified in the studbooks analysed. Up to 315 Asturcón mares and 51 Mallorquí mares that foaled in the last 5years of recording formed a reference population. Only 35 Asturcón and 13 Mallorquí founder dam lines were represented in their reference populations. Sequences from a total of 38 Asturcón and 12 Mallorquí dam lines could be obtained. The 179 sequences obtained gave 15 different haplotypes, 11 and 9 of them being identified, respectively, in the Asturcón pony and in the Mallorquí horse. Five different haplotypes (roughly two-thirds of the sequences) were shared by the two horse breeds. Most dam lines analysed had a single mtDNA haplotype. However, more than one haplotype was detected within eight of the dam lines in Asturcón pony. The found inconsistencies are likely to result from deficiencies in genebank management. The maternal Ne (mNe) computed using the dam line information was higher in the Asturcón pony (20.5) than in the Mallorquí horse (15.9), while these figures were on the opposite direction for the haplotypic line information (6.4 and 9.4, respectively). The ratio of the computed mNe values to the actual number of founder dam lines were always higher in the Mallorquí horse probably due to a more balanced distribution of individuals kept for reproduction among studs. Consequences for the conservation programmes of the analysed breeds are discussed. © 2012 Blackwell Verlag GmbH.

Alvarez I.,Area de Genetica y Reproduccion Animal | Royo L.J.,Area de Genetica y Reproduccion Animal | Perez-Pardal L.,Area de Genetica y Reproduccion Animal | Fernandez I.,Area de Genetica y Reproduccion Animal | And 2 more authors.
Livestock Science | Year: 2011

The bay-Asturcón pony (A21) population recovery started recently. A total of 297 samples (180 from founder individuals) belonging to the A21 population were genotyped for: a) a set of 15 microsatellites; and b) the presence of the two recessive chestnut alleles reported in the literature (e and ea) on the MC1r gene (locus Extension) and the deletion on the ASIP gene (locus Agouti) associated with recessive black coat in horses. The extent to which the genetic variability of the A21 population could be affected by selection strategies aimed at decreasing the frequency of the chestnut allele was quantified in terms of gene diversity and allelic richness. The possible genetic impact of a controlled introgression of A21 offspring into the black-coated Asturcón (A20) population was also assessed using 261 available A20 genotypes. The wild alleles for the Extension and Agouti loci (E and A, respectively) were the most frequent (77.8% and 59.4%) in the A21 population. Both the e and ea recessive chestnut alleles were identified with frequencies of 21.2% and 1.0%. As expected, the contribution to overall diversity of the founder subpopulation was always higher than that of the A21 offspring subpopulation. Total contribution of the offspring subpopulation to overall allelic richness was negative (-1.84%), showing that all their alleles were present in the founder subpopulation. Although favourable, the chestnut carrier individuals had poor contributions to overall gene diversity and tended to have negative contributions to allelic richness. The elimination of the chestnut carrier A21 individuals would not affect genetic variability to a significant extent. Therefore, efforts for preserving the genetic variability in the A21 population could focus on a careful planning of matings between individuals free of the recessive chestnut alleles. The expected influence of a controlled introgression of A21 offspring on the genetic variability of the A20 population was always favourable. The gene diversity of the introgressed population was higher than that of the original A20 population for both gene diversity (GDT=-1.2%±0.04%) and, particularly, allelic richness (CT=4.9%±0.27%). Very limited gene flow may increase the number of alleles of the A20 population but also would yield a balance of the allelic frequencies at a population level. Therefore, a common breeding policy for the two Asturcón pony populations may ensure the viability of this prominent genetic resource. © 2010 Elsevier B.V.

Goyache F.,SERIDA Deva | Alvarez I.,SERIDA Deva | Fernandez I.,SERIDA Deva | Perez-Pardal L.,SERIDA Deva | And 2 more authors.
Journal of Animal Science | Year: 2011

Empirical evidence of the usefulness of different molecular-based methods to estimate the effective population size (N e) for conservation purposes in endangered livestock populations is reported. The black-coated Asturcon pony pedigree (1,981 individuals) was available. Additionally, a total of 267 Asturcon individuals born in 1998, 2002, and 2008 were typed for 15 microsatellites. These yearly cohorts (cohort 1998, 2002, 2008) included almost all individuals kept for reproduction at the end of the corresponding foaling season. The genealogical realized N e (N e) was estimated for each cohort by using the individual increase in inbreeding. Molecular N e was computed by using 1) linkage disequilibrium [N e(D)], 2) a temporal method based on F-statistics [N e(T)], 3) an unbiased temporal method [N e(JR)], and 4) a Bayesian temporal method [N e(B)]. Estimates of Ne increased from cohort 1998 (18.8±5.1) to cohort2008 (24.9±5.2), illustrating the history of the population and its breeding policy of avoiding matings between close relatives. The estimates of N e(D) were highly biased upward, with the maximum N e(D) value obtained for cohort 2002 (137.0). The estimates of N e(T), N e(JR), and N e(B) showed similar performance. However, N e(JR) estimates were very consistent across cohorts, varying from 14.9 to 15.5 after correcting for the effect of overlapping generations. When the drift signal was not strong (pair cohort 1998-cohort 2002), estimates of N e(T) and N e(B) were not realistic. Estimates of N e(B) tended to be biased downward (being 9.0 or below for the sampling pairs including cohort 2008). Results of N e(D) are more likely to be estimates of the effective number of breeders producing the sample, rather than the effective size for a generation. The temporal methods were strongly affected by a weak drift signal, particularly when samplings were not spaced a sufficient number of generations or a sufficient time apart. The use of molecular-based estimates of Ne is not straightforward, and their use in livestock conservation programs should be carried out with caution. Sampling strategies (including sampling sizes, sampling periods, and the age structure of the sampled individuals) must be carefully planned to ensure that robust estimates of N e are obtained. © 2011 American Society of Animal Science. All rights reserved.

Alvarez I.,SERIDA Deva | Fernandez I.,SERIDA Deva | Cuervo M.,SERPA S.A. | Martin D.,Centro Ecuestre El Asturcon | And 2 more authors.
Spanish Journal of Agricultural Research | Year: 2013

A 380 bp fragment of the horse D-loop region was analysed in 42 founder mare samples of the bay-coated Asturcón pony obtained in three different and reproductively isolated mountainous areas of Western Asturias: range of "La Bobia" (20), range of "Carondio" (13) and range of "El Aguión" (9). These sequences were compared with the information provided by 37 founder matrilines of black-coated Asturcón assigned to the range of "Sueve" (26) and the "out-of-Sueve" (11) founder populations. The aim of this research was to ascertain the differences in founder mtDNA diversity between the two strains of the Asturcón pony and if such differences have geographical consistency. The 79 sequences analysed gave 16 different haplotypes defined by 33 polymorphic sites. The two Asturcón strains shared eight haplotypes that gathered 76% and 81% of the samples available in bay-coated and black-coated Asturcón, respectively. Both haplotypic (0.027 ± 0.006) and nucleotide (0.021 ± 0.011) diversity were higher in the bay-coated than in the black-coated Asturcón (0.024±0.005 and 0.016±0.009, respectively). AMOVA analyses failed in assessing any statistically differentiation among Asturcón geographical populations or strains. Most genetic variability is due to the individuals (estimates varying from 96.34% to 99.81%). Differentiation among strains or population took low and non-significant values. Differentiation between Asturcón pony strains using mtDNA marker would not have clear support. The two strains of the Asturcón pony breed likely derive from the same ancestral mare population.

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