[1] Univ Auckland, Dept Comp Sci, Auckland 1, New Zealand
[2] Univ Auckland, Allan Wilson Ctr Mol Ecol & Evolut, Auckland 1, New Zealand
[3] Univ Calif Los Angeles, David Geffen Sch Med, Dept Biomath, Los Angeles, CA 90095 USA
[4] Univ Calif Los Angeles, David Geffen Sch Med, Dept Human Genet, Los Angeles, CA 90095 USA
[5] Univ Calif Los Angeles, Sch Publ Hlth, Dept Biostat, Los Angeles, CA 90024 USA
[6] Univ Edinburgh, Inst Evolutionary Biol, Edinburgh, Midlothian, Scotland