Evidential segregation analysis for offspring sex ratio in rabbit and sheep populations
Casellas Vidal, Joaquim (Universitat Autònoma de Barcelona. Departament de Ciència Animal i dels Aliments)
Vázquez-Gómez, Marta (Sorbonne Université)
Id-Lahoucine, Samir (Scotland's Rural College. Department of Animal and Veterinary Sciences)
de Hijas Villalba, Melani Martín (Universitat Autònoma de Barcelona. Departament de Ciència Animal i dels Aliments)

Data:	2023
Resum:	Offspring sex ratio has been found to be altered by environmental and genetic distortions in multiple species, against the Mendelian inheritance rules. However, little is known in livestock populations where it is essential to validate whether a polymorphic major gene with relevant effects may segregate in the target population. However, the current analytical tool (model FREQ) cannot handle new mutations in non-founder individuals, reducing the chance of detecting them. Our new analytical approach aimed to overcome this limitation in the context of evidential inference, a statistical framework based on the likelihood function as a robust objective measure of the strength of statistical evidence without variation from the sample size. Two field data sets from sheep and rabbit populations were used. Models evaluated environmental and inbreeding effects in both species. Our new approach assumed that the mutation primarily arose in an individual of the analyzed data set (model MUTj). Each sire was individually analyzed to determine the most plausible source for the new mutation, if any. The likelihood ratio (LR) against a reference parametrization without mutations (model NULL) was used to test the statistical relevance of systematic effects (LR ≥ 8) and models (LR ≥ 32). Both species revealed relevant departures for offspring sex ratio along the analyzed time frame with strong evidence for the year (LR = 1. 4 × 10 in Ripollesa sheep and LR = 85. 7 in MARET rabbits) and season (LR = 12. 6 in MARET rabbits), although with a fluctuating pattern. The age of the dam reported weak evidence in both species (LR < 4). Inbreeding had a relevant linear impact on both sheep (LR = 60. 7) and rabbit (LR = 780. 4) populations, whereas the quadratic effect only showed strong evidence in MARET rabbits (LR = 8. 3). Regarding the segregation analysis, most models showed an almost homozygous pattern of weak or lacking evidence of new mutations influencing offspring sex ratio. The only species showing strong evidence for the MUTj model (LR > 32) was the Ripollesa sheep, with a ram three to six generations from the founders as the most likely source for a new mutation increasing the odds of daughters. The additive genetic effect of this model for the mutant allele also had strong evidence (LR = 1,195). Therefore, the MUT parametrization can be a valuable analytical tool to check for the possibility of new mutations along the pedigree files, not only before the founders.
Nota:	Altres ajuts: acords transformatius de la UAB
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	Evidential statistics ; Inbreeding ; Logistic regression ; Mutation ; Sex ratio
Publicat a:	Livestock Science, Vol. 277 (november 2023) , p. 105354, ISSN 1878-0490

DOI: 10.1016/j.livsci.2023.105354

7 p, 1.1 MB

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