Unicorn genome sequenced

Researchers release a draft genome of the famous horned equine, cause stir in evolutionary and philosophical circles.

Walter Lee
1 April 2013

A high-quality draft of the unicorn genome is released by the Equid Sequencing Consortium in today’s issue of Philosophical Transactions in Genomic Sciences [1]. Researchers have previously deciphered the genome of the domestic horse [2] and reported partial sequencing data from Przewalski’s horse and the tibetan wild ass [3,4]. The unicorn, however, is the first horned equine to be sequenced. Scientists hope that the new data will explain origins of the horn and help identify key genes that drive horn development.

A whale in the equine tree

Pip (named by Dr. Hofer’s nine-year old daughter Penelope) provided the source for the sequenced DNA. “She just held out her hand with our mix of oats and fairy dust and he walked right over,” said Dr. Hofer. “Pip is the best! Can he stay in my room?” asked Penelope.
(photo credit: Rob Bourdon)

Dr. Elizabeth Siva and her group EMBL-EBI focused on phylogenetic analysis of the data. “Our calculations suggests that the unicorn diverged from a common ancestor with other modern members of the Equidae family, such as zebra and horse, around 14 million years ago.” It’s around this time, she said, that entire chromosomal fragments, most closely related to known narwhal, entered the unicorn lineage. The origin of the unicorn’s horn has long been a topic of debate in the unicorn field, with many considering it to be yet another striking example of convergent evolution. “What this looks like, though,” says Siva “is a genuine instance of intercrossing between a terrestrial and marine mammal.” Although she expects continued skepticism from members of the convergence camp, she’s confident that further analysis will only strengthen initial conclusions.

Technological advances

Professor Matthew Hofer, who has led the unicorn sequencing project since 2011, says the work represents a major technological milestone. His group at UCSC faced numerous challenges not presented by more widely recognized species, whose genomes they have deciphered in the past. “We struggled for months to develop adequate protocols for sample collection and DNA extraction. We just didn’t encounter these sorts of problems with species for which existence has been firmly established.”

Crossing fields

Scientists also expect their finding will contribute to long-standing philosophical debates. A colleague for Professor Hofer’s in the Department of Philosophy, Scott Trimpton, says the work supports a theory according to which nonexistent things are still real [5]. But, she cautions, further scholarly thought must be devoted to the matter. This is not the first time research into horse genetics has transcended academic disciplines. Previously, German researchers studied coat-color genetics of pre-domestic horses to show that paleolithic cave paintings were more literal representations of contemporary animals than previously thought [6].

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