Multidisciplinary approach to genetic variability, inbreeding and fertility in the endangered Sorraia horse breed

Detalhes bibliográficos
Autor(a) principal: Kjöllerström, Helena
Data de Publicação: 2016
Idioma: eng
Título da fonte: Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
Texto Completo: http://hdl.handle.net/10451/30277
Resumo: Tese de doutoramento, Biologia (Biologia da Conservação), Universidade de Lisboa, Faculdade de Ciências, 2016
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spelling Multidisciplinary approach to genetic variability, inbreeding and fertility in the endangered Sorraia horse breedTeses de doutoramento - 2016Domínio/Área Científica::Ciências Naturais::Ciências BiológicasTese de doutoramento, Biologia (Biologia da Conservação), Universidade de Lisboa, Faculdade de Ciências, 2016The Sorraia horse is a primitive breed and regarded as a universal equine genetic resource. Recovered in 1937 in Font’Alva from 12 founder animals it has been managed as a closed population since. There are presently 10 Portuguese and eight German breeders. With only ~150 breeding mares and ~350 animals worldwide, the Sorraia horse population is in critical risk status. The Sorraia is known for low genetic variability, bad sperm quality, and high inbreeding (mean=0.38) that far exceeds those reported in other horse breeds. The information available in the Sorraia Studbook was used to study genetic variability, demographic structure and status of the extant population. Only 7.46 effective founders and 4 effective ancestors characterize the living population, with only 15 animals explaining its overall genetic variability. Inbreeding and average relatedness were extremely high. Inbreeding by generation rate (5.2%) far exceeded that defined by FAO as maximum (1%). In the living population, approximately 97% of the animals had inbreeding values above 0.25. Recently, conservation strategies from the Sorraia Breeders Association have improved some of these parameters: births have increased and average inbreeding and relatedness have stabilized and, in some years, even decreased. We morphologically described two 20-years-apart Sorraia stallions groups (OLD & NEW) based on 26 body measurements. Most body measurements showed low variability coefficients, attesting to the breed’s (and this group’s) phenotypic homogeneity. Although overall body conformation ratio has not changed, we found that Sorraia stallions have become smaller, except for head size. Inbreeding had a significant negative impact on thoracic width and chest circumference in NEW. Yellow dun horses were taller and longer than mouse dun ones. Dark mouse dun horses appeared shorter than the other coat colours. This data should be used as a complementary tool in the current management breeding program. We used STRs, SNPs and CNVs to evaluate the genetic variation in the Sorraia horse and improve genetic management, and looked for efficient markers for parentage testing. Y-linked loci had no polymorphism. Average number of alleles, HO, HE and mean individual heterozygosity were low. Most analysed parameters were better in the German rather than Portuguese population. There were 47 runs of homozygosity regions. Although Structure analysis separated our samples from 13 different breeders in three clusters, FCA (with STRs) and PCA (with SNPs) analysis separated them in two groups: Portugal and Germany. Interchange between countries should be promoted to increase genetic variability and reduce inbreeding. Copy number variations proved to be unsuitable to assess genetic diversity in this highly inbred breed. The genome wide data described herein can help increase heterozygosity by choosing yearly the right combination of sires and mares for reproduction. Data on all Sorraia horses from 1937 until the end of 2010 were used to study inbreeding effects on offspring’s viability at birth and at 6 months of age. A sub-sample was used to analyse inbreeding impact on stallion and mare fertility rates, foaling intervals and age at first parturition. Inbreeding effect on analysed traits was only significant for mare fertility (P=0.003), with a 0.8% decrease fertility by 1% increase in inbreeding. Age of the mare had a quadratic effect, reducing foal mortality (both at birth and at six months of age) and increasing foaling interval with increasing age. Age at first parturition was significantly influenced by stud farm. Chromosomal abnormalities, particularly of sex chromosomes, have been associated with reduced fertility and infertility in horses. We describe the first case of chromosomal abnormalities in this breed: a sub fertile mare with reduced fertility and stallion-like behaviour with mosaic 63,X0/64,XX karyotype (10.45% and 89.55% frequency, respectively). Early detection of sub fertile animals is of paramount importance for the management and conservation of this breed, saving breeder’s time, efforts and money. Eleven phenotypically normal but sub-fertile stallions were studied by karyotyping, sex chromosome sperm-FISH and FKBP6 analysis – a susceptibility locus for impaired acrosome reaction (IAR). All karyotypes were normal 64,XY. Most sperm had normal haploid sex chromosome content, while 11% carried various sex chromosome aneuploidies. There was no correlation between the percentage of sperm sex chromosome abnormalities and inbreeding, sperm morphology or age. All animals had G/G-A/A genotype, corroborating this breed’s low genetic variability. Our findings ruled out chromosomal abnormalities and genetic predisposition for IAR as contributing factors for subfertility in the analysed Sorraia stallions. However, their low fertility could be partially attributed to higher rate of sperm sex chromosome aneuploidies. Even though inbreeding hasn’t had alarming effects on the majority of traits analysed, inbreeding should continue to be controlled and inbreeding depression studies remain vital for the long-term conservation and sustainability of this breed. These results will help improve genetic health and preserve the genetic variability of this extremely rare and primitive horse breed. With this work we hope to help prevent the permanent loss of this iconic and important animal genetic resource.Programa de Desenvolvimento Regional, PRODER (57882)(EU)/Action 2.2.3 (2011-2013); American Quarter Horse Association (AQHA); United States Department of Agricultura (USDA), 2012-67015-19632Oom, Maria do Mar Jácome Félix, 1956-Chowdhary, Bhanu PratapRepositório da Universidade de LisboaKjöllerström, Helena2018-01-05T16:08:01Z201620162016-01-01T00:00:00Zdoctoral thesisinfo:eu-repo/semantics/publishedVersionapplication/pdfhttp://hdl.handle.net/10451/30277TID:101324960enginfo:eu-repo/semantics/openAccessreponame:Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)instname:FCCN, serviços digitais da FCT – Fundação para a Ciência e a Tecnologiainstacron:RCAAP2025-03-17T13:45:26Zoai:repositorio.ulisboa.pt:10451/30277Portal AgregadorONGhttps://www.rcaap.pt/oai/openaireinfo@rcaap.ptopendoar:https://opendoar.ac.uk/repository/71602025-05-29T02:53:10.294612Repositórios Científicos de Acesso Aberto de Portugal (RCAAP) - FCCN, serviços digitais da FCT – Fundação para a Ciência e a Tecnologiafalse
dc.title.none.fl_str_mv Multidisciplinary approach to genetic variability, inbreeding and fertility in the endangered Sorraia horse breed
title Multidisciplinary approach to genetic variability, inbreeding and fertility in the endangered Sorraia horse breed
spellingShingle Multidisciplinary approach to genetic variability, inbreeding and fertility in the endangered Sorraia horse breed
Kjöllerström, Helena
Teses de doutoramento - 2016
Domínio/Área Científica::Ciências Naturais::Ciências Biológicas
title_short Multidisciplinary approach to genetic variability, inbreeding and fertility in the endangered Sorraia horse breed
title_full Multidisciplinary approach to genetic variability, inbreeding and fertility in the endangered Sorraia horse breed
title_fullStr Multidisciplinary approach to genetic variability, inbreeding and fertility in the endangered Sorraia horse breed
title_full_unstemmed Multidisciplinary approach to genetic variability, inbreeding and fertility in the endangered Sorraia horse breed
title_sort Multidisciplinary approach to genetic variability, inbreeding and fertility in the endangered Sorraia horse breed
author Kjöllerström, Helena
author_facet Kjöllerström, Helena
author_role author
dc.contributor.none.fl_str_mv Oom, Maria do Mar Jácome Félix, 1956-
Chowdhary, Bhanu Pratap
Repositório da Universidade de Lisboa
dc.contributor.author.fl_str_mv Kjöllerström, Helena
dc.subject.por.fl_str_mv Teses de doutoramento - 2016
Domínio/Área Científica::Ciências Naturais::Ciências Biológicas
topic Teses de doutoramento - 2016
Domínio/Área Científica::Ciências Naturais::Ciências Biológicas
description Tese de doutoramento, Biologia (Biologia da Conservação), Universidade de Lisboa, Faculdade de Ciências, 2016
publishDate 2016
dc.date.none.fl_str_mv 2016
2016
2016-01-01T00:00:00Z
2018-01-05T16:08:01Z
dc.type.driver.fl_str_mv doctoral thesis
dc.type.status.fl_str_mv info:eu-repo/semantics/publishedVersion
status_str publishedVersion
dc.identifier.uri.fl_str_mv http://hdl.handle.net/10451/30277
TID:101324960
url http://hdl.handle.net/10451/30277
identifier_str_mv TID:101324960
dc.language.iso.fl_str_mv eng
language eng
dc.rights.driver.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.source.none.fl_str_mv reponame:Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
instname:FCCN, serviços digitais da FCT – Fundação para a Ciência e a Tecnologia
instacron:RCAAP
instname_str FCCN, serviços digitais da FCT – Fundação para a Ciência e a Tecnologia
instacron_str RCAAP
institution RCAAP
reponame_str Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
collection Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
repository.name.fl_str_mv Repositórios Científicos de Acesso Aberto de Portugal (RCAAP) - FCCN, serviços digitais da FCT – Fundação para a Ciência e a Tecnologia
repository.mail.fl_str_mv info@rcaap.pt
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