These findings are helping King and her colleagues assemble a picture of what the original common ancestor of humans and choanoflagellates looked like and also get hints about the first animals.
"It remarkable to what extent we can figure out how those animal ancestors must have been able to stick together and communicate with each other, at least in ways that allow you to make hypotheses about what those first steps toward animals looked like," Rokhsar said.
Nevertheless, it is not always easy determining which genes were in the last common ancestor of choanoflagellates and humans, and which are new. Choanoflagellates and humans have been evolving for the same length of time, so differences between the genomes may reflect genes that have been lost by choanoflagellates as much as genes gained by humans. Comparison of the Monosiga genome to that of other organisms, including another choanoflagellate - a colony-former called Proterospongia, whose genome is due to be sequenced by the National Institutes of Health - may answer such questions.
King has hopes that the Monosiga genome will answer many questions of animal evolution and illuminate the biology of this poorly understood aquatic creature.
"This is a new era, where we start with a genome to understand the biology of an organism," King said, noting a similar situation with the starlet sea anemone, Nematostella vectensis, sequenced in 2007. "The genome is the toehold."
|Contact: Robert Sanders|
University of California - Berkeley