Rabbit Genetic Resources Can Provide Several Animal Models to Explain at the Genetic Level the Diversity of Morphological and Physiological Relevant Traits

Abstract

The rabbit (Oryctolagus cuniculus) is a unique multipurpose domestic species that has relevant economic impacts in several contexts. This review is focused on rabbit genetic resources that have been mainly bred for the fixation of differentiating features (e.g., exterior traits) that have been already genetically characterized. Several naturally occurring rabbit mutants could be useful as animal models for the investigation of the biological mechanisms determining their characterizing aspects, with translational potentials. A historical overview of the origin of the domesticated rabbit populations and of their genetic differentiation into many breeds is summarized. Then, a detailed analysis of the genetic features that characterize the different breeds is reported, starting from coat color and coat structure affecting genes (MC1R, ASIP, TYR, MLPH, TYRP1, KIT, LIPH, and FGF5), determining major loci described by classical genetic studies. Mutations in these genes have implications in pigmentation features, hair growth, and related defects. Other gene mutations affecting body size or shapes (HMGA2) and other physiological disfunctions (RORB and BCO2) are also described Additional studies are needed to complete the genetic characterization of some of these loci and to investigate the large genetic variability available in fancy breeds and commercial meat and fur lines.

Genomic diversity and signatures of selection in meat and fancy rabbit breeds based on high-density marker data

“…[36,[73][74][75][76]). The large number of rabbit breeds represents a unique and mostly unexplored resource, which can help to dissect the genetic architecture of external traits in this lagomorph species and, as a mirror, also in other mammals [1]. The rabbit is used as an animal model for applied and basic biological studies, mainly where the rodents have demonstrated several limits [77].…”

“…The European rabbit (Oryctolagus cuniculus), usually simply referred to as rabbit, is the only species that has been domesticated exclusively in western Europe. Its domestication started from the wild populations in the South of France that originally derived from the wild populations of the O. c. cuniculus subspecies spread in the Iberian Peninsula, which experienced a postglacial expansion (reviewed in [1]). Among the possible animal domestication trajectories that have been theorised [2], domestication of the rabbit better matches the directed pathway that does not involve preliminary steps of habituation of animals to human beings and begins with the capture of wild animals, with the aim of controling their breeding and reproduction.…”

“…The domestication process was integrated or was followed by artificial selection processes that led to the constitution of many breeds. The resulting rabbit breeds can be distinguished based on their broad phenotypic diversity, in terms of external traits that are valued by fancy breeders [1,8,9]. It is also worth mentioning that the most recently constituted rabbit lines or strains and the modern breeds have been derived by cross-breeding preexisting varieties or morphs, with the aim to introgress desirable traits to create new lines or combinations of morphological features or to improve production traits in specialized meat lines [1,8,9].…”

“…The resulting rabbit breeds can be distinguished based on their broad phenotypic diversity, in terms of external traits that are valued by fancy breeders [1,8,9]. It is also worth mentioning that the most recently constituted rabbit lines or strains and the modern breeds have been derived by cross-breeding preexisting varieties or morphs, with the aim to introgress desirable traits to create new lines or combinations of morphological features or to improve production traits in specialized meat lines [1,8,9]. However, coat colours and coat colour patterns are the most relevant traits that differentiate many rabbit breeds, as also demonstrated by the fact that many breeds are named according to their colouration [1,9].…”

“…At the English spotting locus, a marker in the v-kit Hardy-Zuckerman 4 feline sarcoma viral oncogene homolog (KIT) gene is associated with the spotted pattern of the Checkered Giant and Rhinelander breeds, whose classical spotted design is due to the heterozygous genotype En/en that preserves these animals from a megacolon defect associated with the En allele [17]. Other coat colour loci might be involved in the spotted phenotypes of rabbits but, to date, the corresponding genes have not been identified [1,10].…”