New methods make global family tree a possibility

The ______ of life.

Almost everyone will fill that blank with the word "circle", maybe accompany it with some singing or imaginary cub-holding.

But if you're Dr. Chris Hittinger, a professor of genomics at UC Denver, the word would be "tree."

This "tree of life" has been a "long-standing problem in biology," Hittinger said.

The idea is simple; it's a family tree. The complicated part is that biologists want to include every living species on good ‘ol Mama Earth.

"All two million species," said Hittinger. "It's a daunting task."

"There's been a desire since Darwin to classify all organisms on the planet," said Dr. Mark Johnston, the chief investigator on the team. "So far, only a small portion of the species have been identified."

So instead of trying to organize the whole globe into this one tree, Hittinger and his team decided to start small. Tiny, actually; they started with mosquitoes.

"Mosquitoes are very complex creatures," Hittinger explained, "and they have many different cell types." The goal of the team is to find how every species of mosquito known to man are related to one another.

"Historically, this has always been looked at from a morphological standpoint," said Hittinger. In English, this means that scientists would observe physical characteristics, such as number of limbs, types of skin, number of eyes, and other visible traits, in order to see relations between different species.

"They were a very arbitrary comparison," Hittinger explained, "and very subjective."
Scratch that method out.

Then came DNA sequencing. This would allow scientists to look at the genetic code of certain species and compare them to others.

The problem?

"It's expensive and labor-intensive," Hittinger said. What you get in accuracy, you end up losing in time and money.

That's where Hittinger comes in.

"Our new method is called ‘next generation DNA sequencing tech,'" he said, "and it leverages a natural property of the genome."

This property is that certain parts of your DNA are expressed more heavily than others. Some genes are heavyweights, while others can't even throw a good punch.

"This property simplifies the whole process and allows us to sample portions of the DNA very, very deeply," Hittinger explained, "and this makes for very accurate results."

Beyond that, Hittinger's method is a fraction of the cost of normal DNA sequencing. Not only that, but it's faster.

"It's unbelievable how fast it works," Johnston said.

"This method works so well," said Hittinger. "We haven't even been working that long."

From concept to publishing, the project only took a little over a year; in the scientific world, that's blazing fast.

"We were amazed at how well it works," he said. "When something works better than expected, it's possible to make pretty rapid progress."

But progress on what? Finding out how mosquitoes are related? Not too many people are holding their breath about how many cousins separate one species from another.

The goal is a little more productive than that. "We want to influence how the relationships of organisms are classified in the future," Hittinger said.

Not only that, but the team wants "broader adoption of this process in the scientific community."

"This definitely cuts down on the time and resources used when doing genomic sequencing," said Hittinger. "And as the cost of sequencing drops, our method might be able to render this ‘dream of Darwin's' to be resolved in our lifetime."

So when will "Darwin's dream" come to fruition?

"I would say within 10 to 20 years," Hittinger said. Two decades, he estimated, was all it would take to make a family tree of life on Earth.

"Pretty soon, the only limiting factor will be gathering raw material from the organisms," Hittinger said.