Molecular and Computational Biology Program, University of Southern California, Los Angeles, CA, USA.|School of Mathematical Sciences, Peking University, Beijing, China.|School of Mathematical Sciences, Peking University, Beijing, China.|Department of Statistics, University of Oxford, 1 South Parks Road, Oxford OX1 3TG, UK.|Department of Biological Sciences, Texas Tech University, TX 79409-3131, USA, Xishuangbanna Tropical Botanic Garden, Chinese Academy of Sciences, Yunnan, China and.|Molecular and Computational Biology Program, University of Southern California, Los Angeles, CA, USA, Centre for Computational Systems Biology, School of Mathematical Sciences, Fudan University, Shanghai, China.