title: Genetic structure of an endangered Portuguese semiferal pony breed, the Garrano.
abstract: The present study intends to survey the genetic variability of an endangered semiferal Portuguese native pony breed, the Garrano. Thirteen microsatellite markers were examined in 277 animals born in 1998, belonging to eight subpopulations corresponding to eight northern Portuguese geographic regions. Mean heterozygosity (H(o)) in the Garrano breed was 0.732, ranging from 0.531 to 0.857 across subpopulations. Allelic frequencies and diversity differed significantly between regions, suggesting the existence of genetic differentiation within the breed confirmed by the population differentiation estimator F(ST). Allele sharing genetic distance (Dps) was used to determine the relationship between the analyzed subpopulations, some of which are diverging significantly from the others. Relationships among six Iberian horse breeds (including the Garrano) were assessed through the restricted maximum likelihood method, which clusters the Garrano with another Celtic pony, the Spanish Asturcon, traditionally bred in geographical continuity with the Garrano. Results reveal a statistically significant deficit of heterozygotes within the Garrano breed (F(IT) = 0.031, p < 0.05). Regular monitoring should therefore be implemented so that the effect of genetic drift within subpopulations, enhanced by inbreeding, may be successfully minimized.
authors.affiliation: Centro de Biologia Ambiental, Departamento de Biologia Animal, Faculdade de Ciências da Universidade de Lisboa, Lisboa, Portugal.
authors.forename: Joana
authors.initials: J
authors.lastname: Morais
authors.forename: Maria M
authors.initials: MM
authors.lastname: Oom
authors.forename: Joana
authors.initials: J
authors.lastname: Malta-Vacas
authors.forename: Cristina
authors.initials: C
authors.lastname: Luís
mesh_terms: D000483:Alleles; D000818:Animals; D000835:Animals, Wild / Q000235:genetics*; D001947:Breeding / Q000706:statistics & numerical data*; D016000:Cluster Analysis; D003247:Conservation of Natural Resources; D005787:Gene Frequency; D040961:Genetic Drift; D014644:Genetic Variation; D005828:Genetics, Population; D005843:Geography; D006579:Heterozygote; D006736:Horses / Q000145:classification* / Q000235:genetics*; D007178:Inbreeding; D016013:Likelihood Functions; D018895:Microsatellite Repeats; D011174:Portugal; D013045:Species Specificity