Positive selection drives the evolution of rhino, a member of the heterochromatin protein 1 family in Drosophila.

"all sequences have been deposited in genbank (accession numbers ay944308-ay944358 table s2 ).; new sequences obtained during the course of this study have been deposited in genbank under the accession numbers ay944308-ay944358. table s2 (36 kb xls"

"Competing interests. The authors have declared that no competing interests exist."

"We thank the Drosophila stock center (Tucson, Arizona) for various Drosophila species stocks and Judy O'Brien for maintenance of Drosophila stocks. We are grateful to Kami Ahmad and Celeste Berg for useful discussions throughout this project, and Jiro Yasuhara, Barbara Wakimoto, Sara Sawyer, and Julie Kerns for comments on the manuscript. We also gratefully acknowledge Terri Bryson for help with maintenance of Drosophila tissue culture cells, and Takehito Furuyama for the BLRP and pBirA plasmids. This work was supported by a Damon Runyon Cancer Postdoctoral Fellowship (DV), by the Howard Hughes Medical Institute (SH), startup funds from the Fred Hutchinson Cancer Research Center, and a Scholar Award from the Sidney Kimmel Foundation (HSM). HSM is an Alfred P. Sloan Fellow in Computational and Evolutionary Molecular Biology."