London: Genes controlling the development of the brain and the nervous system were particularly important for animal domestication, suggests a new study on rabbits.
The domestication of animals and plants, a prerequisite for the development of agriculture, is one of the most important technological revolutions during human history, researchers said.
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.
For the study, scientists first sequenced the entire genome of one domestic rabbit to develop a reference genome assembly.
Then they resequenced entire genomes of domestic rabbits representing six different breeds and wild rabbits sampled at 14 different places across the Iberian Peninsula and southern France.
"This allowed us to pinpoint the genetic changes that have occurred during rabbit domestication," said Leif Andersson from Uppsala University, Swedish University of Agricultural Sciences and Texas A&M University.
Rabbit 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," said Kerstin Lindblad-Toh, co-senior author, Director of Vertebrate Genome Biology at the Broad Institute of MIT and Harvard, professor at Uppsala University and Co-Director of Science for Life Laboratory.
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 favoured in domestic rabbits.
The study showed that the wild rabbit is a highly polymorphic species that carries gene variants that were favourable 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, said Andersson.
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 behaviour, Andersson said.