New research reveals how wild rabbits were genetically transformed into tame rabbits
COLLEGE STATION, Texas – The genetic changes that transformed wild animals into domesticated forms have long been a mystery. However, an international team of scientists has made a breakthrough by showing that many genes controlling the development of the brain and the nervous system were particularly important for rabbit domestication, according to a study published today in the journal Science.
The domestication of animals and plants, a prerequisite for the development of agriculture, is one of the most important technological revolutions during human history. Domestication of animals started as early as 9,000 to 15,000 years ago and initially involved dogs, cattle, sheep, goats, and pigs. The rabbit was domesticated much later, about 1,400 years ago, at monasteries in southern France. When domestication occurred, the wild ancestor, the European rabbit (Oryctolagus cuniculus), was confined to the Iberian Peninsula and southern France.
“There are several reasons why the rabbit is an outstanding model for genetic studies of domestication,” said Miguel Carneiro, from CIBIO/Inbio-University of Porto, one of the leading authors on the paper. “Its domestication was relatively recent, we know where it happened, and this region is still densely populated with wild rabbits.”
The scientists first sequenced the entire genome of one domestic rabbit to develop a reference genome assembly. Then they re-sequenced entire genomes of domestic rabbits representing six different breeds and wild rabbits sampled at 14 different places across the Iberian Peninsula and southern France.
“No previous study on animal domestication has involved such a careful examination of genetic variation in the wild ancestral species,” said Leif Andersson of Uppsala University, Swedish University of Agricultural Sciences, and Texas A&M University. “This allowed us to pinpoint the genetic changes that have occurred during rabbit domestication.”
This domestication has primarily occurred by altering the frequencies of gene variants that were already present in the wild ancestor. “Our data shows that domestication primarily involved small changes in many genes, and not drastic changes in a few genes,” continued Andersson.
The team observed very few examples where a gene variant common in domestic rabbits had completely replaced the gene variant present in wild rabbits; it was rather shifts in frequencies of those variants that were favored in domestic rabbits.
“The results we have are very clear,” Carneiro said. “The difference between a wild and a tame rabbit is not which genes they carry but how their genes are regulated-when and how much of each gene is used in different cells.”
The study also revealed which genes have been altered during domestication, most noticeably strong enrichment in domestic rabbits of genes involved in the development of the brain and the nervous system.
The study shows that the wild rabbit is a highly polymorphic species that carries gene variants that were favorable during domestication, and that the accumulation of many small changes led to the inhibition of the strong flight response-one of the most prominent phenotypic changes in the evolution of the domestic rabbit.
“We predict that a similar process has occurred in other domestic animals and that we will not find a few specific ‘domestication genes’ that were critical for domestication,” Andersson said. “It is very likely that a similar diversity of gene variants affecting the brain and the nervous system occurs in the human population and that contributes to differences in personality and behavior.”
