Exploring the Genetic Background of the Differences in Nest-Building Behavior in European Rabbit

SIMPLE SUMMARY: The rabbit is one of the genetically most diverse farm animals, where domestication has resulted in a change primarily in the genes responsible for behavior. The elements of intensive production technology (e.g., nursing, change of nest material) can have a significant effect on maternal behavior. Its individual variability is evident in the timing of nest building and nest composition. As a result that the hormone progesterone strongly influences the steps of nest building, we investigated the association of genetic mutations in the progesterone receptor gene with nest-building behavior in wild-type rabbit does. In addition to the already described point mutations in domesticated lines, we detected a new mutation in our wild type rabbits. However, the timing of nest building (hay carrying) was related to an already described point mutation. The heritability of this trait was low, but it confirms the genetic determination of the behavior besides the environmental factors. One of the genotypes was responsible for the two days earlier initiation of the hay carrying behavior. The early initiation of this process allows animals to construct a high-quality nest resulting in better survival of the offsprings in nature. ABSTRACT: Once a day, nursing and absentee mothering make the wild rabbit (Oryctolagus cuniculus) an ideal model animal for measuring differences in maternal behavior. Behavioral events and their hormonal regulation leading to parturition are well documented; however, the genetic background behind individual differences in this complex process is unknown. Decreased progesterone hormone level and the reduction of progesterone receptor activity are crucial to initiating the collection of nest material. The progesterone receptor gene is a likely candidate affecting nest-building behavior. In addition to several known point mutations in the progesterone receptor gene of the European wild rabbit, we have found a new mutation in the promoter region of the gene at 2682 T > C. Although this new single nucleotide polymorphism (SNP) was not involved in the formation of the nest-building behavior, an SNP (2464G > A) already described in the promoter region showed an association with individual differences in the initiation of hay carrying. The distribution of this SNP delivered an opposite result compared to domestic rabbits. Genotype (GG) with high uterine capacity was most frequent; the hereditary value of the trait was h(2) = 0.10. Thus, progesterone receptor gene polymorphism may manifest in individual differences affecting breeding success in this species.