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Genetics, selection, evolution : GSE2020; 52(1); 62; doi: 10.1186/s12711-020-00582-2

Genetic inbreeding depression load for morphological traits and defects in the Pura Raza Española horse.

Abstract: Inbreeding is caused by mating between related individuals and is associated with reduced fitness and performance (inbreeding depression). Several studies have detected heterogeneity in inbreeding depression among founder individuals. Recently, a procedure was developed to predict hidden inbreeding depression load that is associated with founders using the Mendelian sampling of non-founders. The objectives of this study were to: (1) analyse the population structure and general inbreeding, and (2) test this recent approach for predicting hidden inbreeding depression load for four morphological traits and two morphology defects in the Pura Raza Española (PRE) horse breed. Results: The regression coefficients that were calculated between trait performances and inbreeding coefficients demonstrated the existence of inbreeding depression. In total, 58,772,533 partial inbreeding coefficients (F) were estimated for the whole PRE population (328,706 horses). We selected the descendants of horses with a F ≥ 6.25% that contributed to at least four offspring and for which morphological traits were measured for the subsequent analysis of inbreeding depression load (639 horses). A pedigree was generated with the last five generations (5026 animals) used as the reference population (average inbreeding coefficient of 8.39% and average relatedness coefficient of 10.76%). Heritability estimates ranged from 0.08 (cresty neck) to 0.80 (height at withers), whereas inbreeding depression load ratios ranged from 0.01 (knock knee) to 0.40 (length of shoulder), for an inbreeding coefficient of 10%. Most of the correlations between additive and inbreeding depression load genetic values and correlations between inbreeding depression load genetic values for the different traits were positive or near 0. Conclusions: Although the average inbreeding depression loads presented negative values, a certain percentage of the animals showed neutral or even positive values. Thus, high levels of inbreeding do not always lead to a decrease in mean phenotypic value or an increase in morphological defects. Hence, individual inbreeding depression loads could be used as a tool to select the most appropriate breeding animals. The possibility of selecting horses that have a high genetic value and are more resistant to the deleterious effects of inbreeding should help improve selection outcomes.
Publication Date: 2020-10-20 PubMed ID: 33081691PubMed Central: PMC7576714DOI: 10.1186/s12711-020-00582-2Google Scholar: Lookup
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  • Journal Article

Summary

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The research studies the negative effects of inbreeding on four morphological traits and two morphology defects in the Pura Raza Española horse breed. Through an analysis of the population structure and inbreeding levels, the study finds that higher levels of inbreeding don’t always lead to decreased average phenotypic value or increased morphological defects, suggesting potential for a more nuanced approach to breeding selection.

Study Objectives and Methodology

  • Inbreeding, the mating between related individuals, is known to cause reduced fitness and performance – a phenomenon known as inbreeding depression. The researchers aimed to analyze this in the Pura Raza Española horse breed.
  • The study had two main objectives. First, they analyzed the population structure and the general levels of inbreeding. Second, they tested an approach for predicting hidden inbreeding depression, associated with traits and defects, among the founders of the breed.

Results and Findings

  • The study used regression coefficients between performance and inbreeding coefficients, revealing the existence of inbreeding depression.
  • Partial inbreeding coefficients for the whole breed were estimated and a smaller subset of horses with higher inbreeding potential were selected for further analysis.
  • Overall, the analysis found heritability estimates ranging from 0.08 for cresty neck to 0.80 for height at withers, while inbreeding depression load ratios ranged from 0.01 for knock knee to 0.40 for length of shoulder.

Conclusions and Implications

  • Despite negative average inbreeding depression loads, a proportion of animals showed neutral or even positive values. That means significant inbreeding does not necessarily cause average phenotypic value decrease or morphological defects increase.
  • As a result, the researchers suggest individual inbreeding depression loads could be helpful in selecting ideal breeding animals, adding a more nuanced approach in the breeding selection protocol.
  • This discovery paves the way for selecting horses with higher genetic value that are more resistant to inbreeding’s damaging effects, potentially leading to improved selection results.

Cite This Article

APA
Poyato-Bonilla J, Perdomo-González DI, Sánchez-Guerrero MJ, Varona L, Molina A, Casellas J, Valera M. (2020). Genetic inbreeding depression load for morphological traits and defects in the Pura Raza Española horse. Genet Sel Evol, 52(1), 62. https://doi.org/10.1186/s12711-020-00582-2

Publication

ISSN: 1297-9686
NlmUniqueID: 9114088
Country: France
Language: English
Volume: 52
Issue: 1
Pages: 62
PII: 62

Researcher Affiliations

Poyato-Bonilla, Julia
  • Departamento de Ciencias Agroforestales, ETSIA, Universidad de Sevilla, Ctra. Utrera km. 1, 41013, Sevilla, Spain.
Perdomo-González, Davinia I
  • Departamento de Ciencias Agroforestales, ETSIA, Universidad de Sevilla, Ctra. Utrera km. 1, 41013, Sevilla, Spain. davpergon1@alum.us.es.
Sánchez-Guerrero, María J
  • Departamento de Ciencias Agroforestales, ETSIA, Universidad de Sevilla, Ctra. Utrera km. 1, 41013, Sevilla, Spain.
Varona, Luis
  • Departamento de Anatomía Embriología Y Genética Animal, Instituto Agroalimentario de Aragón (IA2), Universidad de Zaragoza, Zaragoza, 50013, Spain.
Molina, Antonio
  • Departamento de Genética, Universidad de Córdoba, Córdoba, 14071, Spain.
Casellas, Joaquim
  • Departament de Ciència Animal I Dels Aliments, Universitat Autònoma de Barcelona, Bellaterra, 08193, Spain.
Valera, Mercedes
  • Departamento de Ciencias Agroforestales, ETSIA, Universidad de Sevilla, Ctra. Utrera km. 1, 41013, Sevilla, Spain.

MeSH Terms

  • Animals
  • Genetic Fitness
  • Genetic Load
  • Horses / anatomy & histology
  • Horses / genetics
  • Inbreeding Depression
  • Pedigree
  • Quantitative Trait, Heritable

Grant Funding

  • AGL-2017-84217-P / Ministerio de Economu00eda, Industria y Competitividad, Gobierno de Espau00f1a

Conflict of Interest Statement

The authors declare that they have no competing interests.

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Citations

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