Acknowledgements We thank James A. DOYLE, Peter K. ENDRESS, Timothy Y. JAMES, Paul KENRICK, and Michael J. WYNNE for helpful discussion, Christiane ANDERSON, Thomas E DUDA, Jr., James A. DOYLE, Evan ECONOMO, and Peter K. ENDRESS for help with literature search, and James A. DOYLE for carefully editing the manuscript. This work was supported by National Science Foundation grants DEB 0332298 and 0531689 to YLQ.
All sexually reproducing eukaryotes have a life cycle consisting of a haploid and a diploid phase, marked by meiosis and syngamy (fertilization). Each phase is adapted to certain environmental conditions. In land pl...