The most important genomic study of an organism unveiled in 2013 was not an analysis of an impressive collection of great big cats, nor was it the Coelacanth project, which delved into the DNA of the mysterious and ancient fish of the deep.
These were both impressive projects, to be sure, according to Science News, and they rank among the top few smash hit genomes to hit the journals over the past year. But the star of 2013 was the genome of the humble comb jelly, or ctenophore.
That's the project that upended long-standing notions about which animals are the most primitive on Earth.
Ctenophores were seen as the last remaining group of primitive animals to have its genome sequenced, which enabled investigators to compare it to other simple creatures.
The researchers say the analysis of the genome of Mnemiopsis leidyi, or the sea walnut, suggests that it is the most primitive animal on the planet – more primitive even than sponges – even though it possesses some traits, like muscles and nerve cells, which the sponges lack. That would mean that some of these traits in ctenophores were lost by the sponges as they arose.
And that would suggest that animal evolution did not advance evenly from the simple to the complex, the researchers say.
"With our whole-genome sequencing data in hand, it is now clear that the cell types that make up muscles and nervous systems were either lost in some animal lineages or that, despite the complexity of these cells, they very well may have evolved multiple times," Joseph Ryan, lead author on the project, explained earlier this month.
The runner-up genome of the year belongs to a roughly 700,000 year-old wild horse, which not only offers a deeper picture of horse evolution and domestication, but also raises the possibility that human ancestors who are just as old also may have their genomes fully sequenced.
Over the course of 2013, New Science also notes, investigators released genome sequences of a Siberian tiger, a Bengal tiger, an African Lion, a white African lion, and a snow leopard.
Also this year, a mallard duck genome yielded clues about how flu viruses that can strike in humans can develop in waterfowl, a Norway spruce tree proved to be the largest genome sequenced to date, and the Coelacanth genome proved showed that it is not the closest living relative to tetrapods, but that lungfish hold that title.