Comparison of genetic models for analysing the effects of a PvuII polymorphism in the oestrogen receptor 1 (ESR1) gene on prolificacy in an Iberian × Meishan pig population

Summary The effect of a previously reported PvuII polymorphism in oestrogen receptor1 (ESR1) was analysed in an F2 population of Iberian × Meishan pigs. We tested three hypotheses: (1) that a causalmutation was fixed in the parental populations, (2) that a causalmutation existed that was in complete linkage disequilibriumwith the alleles of the PvuII polymorphism and (3) that a causalmutation existed in linkage disequilibriumwithin each parental population. The third model was the most plausible based on the available data. ESR1 alleles displayed different patterns of linkage disequilibriumwith the causalmutation in each of the parental populations and the PvuII polymorphism was clearly not the causalmutation. As a consequence, the use of the ESR1 mutation for selection must be evaluated for a particular pig population before it is applied.