Apathy, weary sighs, and fatigue: these are the symptoms of the psychological malaise that Carl Zimmer calls Yet Another Genome Syndrome. It is caused by the fast-flowing stream of publications, announcing the sequencing of another complete genome.
News reports about such publications tend to follow the same pattern. Scientists have deciphered the full genome of Animal X, which is known for Traits Y and Z, which could include commercial importance, social behaviour, being closely related to us, or just being exceptionally weird. By understanding X’s collection of As, Gs, Cs and Ts, we may gain insights into the genetic basis of Y and Z, which will be terribly important and there will be parties and cake.
Note the future tense. The value in sequencing yet another genome is almost never in the act itself, but in enabling an entire line of subsequent research. It’s the harbinger of news; it’s rarely news itself.
But there are exceptions. This week, there’s a paper about a new animal genome that goes the extra mile. It includes not just one full sequence, but twenty-one. It doesn’t just spell out the creature’s DNA, but also uses it to address some big questions in evolutionary biology. And its protagonist is a small, unassuming fish – the three-spined stickleback.
Sticklebacks are just a few inches long, and defend themselves with spines and plates of body armour running down their sides. But they fascinate scientists not for how they look, but what they did. Sticklebacks originally lived in the ocean, and many still do. When the last Ice Age ended some 10,000 years ago, retreating glaciers allowed the fish to repeatedly invade the world’s streams and lakes. In freshwater, they faced weaker but faster predators, so they lost their spines and armour and became smaller and more agile. Their lifestyles, colour, mating habits, salt tolerance and diets also changed.
Freshwater sticklebacks around the world have independently picked ..., often by tweaking the same genes, and often in just a few generations. This rich history has turned the three-spined stickleback into a supermodel of evolutionary biology. It gives us an unprecedented look at how species adapt to new environments, and whether they do so in predictable ways.
David Kingsley from Stanford University has been studying the stickleback for many years, and his team have now published the animal’s full genome. They first sequenced a single female from Bear Paw Lake in Alaska, going over each part of her DNA around 9 times. Most genome papers leave things there, but Kingsley’s group also sequenced 10 other pairs of sticklebacks from Asia, North America and Europe. Each pair included a freshwater fish, and a marine one from a connected population.
Read the rest here.