Size Matters: The Daphnia Genome

The Daphnia, or water flea,

Contains more genes than you or me;

Five thousand more at least, you see,

The most we’ve seen amass!

The Daphnia’s thirty-one thousand genes

Allow adaptiveness, which means

Its features change to match the scenes

As generations pass

The Daphnia is closely tracked;

As waters change, these fleas react,

Evolving spikes that once they lacked

Which make them tough to swallow

To predators, to day and night,

To changes from pollution’s blight,

To water change, however slight,

Mutations soon will follow

The genes of Daphnia create

New copies at a higher rate—

A rate perhaps three times as great

As similar crustaceans

Environmental pressures yield

A spear-like tail, or spiky shield

Which reproduction soon revealed

Were useful adaptations

Our egotistic human eyes

Dismiss these useless little guys

And focus on our larger size

Which demonstrates our worth

But as our chromosomes are mapped

We find the Daphnia more apt

To test the waters, then adapt

And populate the earth

NPR reports on the results of a recent genome analysis, of one of the most well-studied organisms around... one you may have accidentally swallowed while swimming in a lake, without realizing it.  Now, I don't have access to Science, but a quick search found a press release from one of the many universities involved: 

Scientists have studied Daphnia for centuries because of its importance in aquatic food webs and for its transformational responses to environmental stress. Predators signal some of the animals to produce exaggerated spines, neck-teeth or helmets in self-defense. And like the virgin nymph of Greek mythology that shares its name, Daphnia thrives in the absence of males -- by clonal reproduction, until harsh environmental conditions favor the benefits of sex.

Arguably, more is known about the ecology and stress biology of the water flea than any other animal. The genome project was conceived with an expectation that many new gene functions would be uncovered when studied in light of the animal's natural environment -- not necessarily expecting to discover many more genes.

Yet, Daphnia's genome is no ordinary genome.

"Daphnia's high gene number is largely because its genes are multiplying, by creating copies at a higher rate than other species," said project leader and CGB genomics director John Colbourne. "We estimate a rate that is three times greater than those of other invertebrates and 30 percent greater than that of human."

"One theory is that Daphnia is so good at adapting to so many environments because it has this huge catalog of genes to call upon," says Thomas. The researchers note that more than one-third of Daphnia's genes are undocumented in any other organism – they are completely new to science.

Daphnia, as I understand it, have been used as a barometer of lake condition, because they are so sensitive to conditions, and so quick to adapt (across generations, not within).  The combination of an environmentally sensitive species well studied as an ecoresponsive indicator, and a thorough understanding of the underlying genetics, will allow an unprecedented depth of understanding in examining epigenetic processes.

Or, maybe I misunderstood everything.

An update, of sorts.  I just saw this really nice pdf file of my verse.  Apparently, I'm listed on the Daphnia Genomics Consortium Collaboration Wiki... and apparently, somebody made a really nice pdf of my verse without asking (tsk, tsk!).