Author contributions

X.S.H, H.Q.C., X.Z. and Z.L. designed the research; X.S.H., H.Q.C., Z.Y.D. conducted the fieldwork; H.Q.C. carried genetic analysis and analyzed the data; C.Y.W., X.S.H. and H.Q.C drafted the manuscript; X.Y.S. reviewed and improved the manuscript; X.S.H. and H.Q.C. produced the figures. All authors contributed critically to the drafts and gave final approval for publication.