Mathematics, Department of


Date of this Version



2105 Published in Bulletin of Mathematical Biology 69:6 (2007), pp. 2105-2114 doi: 10.1007/s11538-007-9215-z


Copyright © 2007 Society for Mathematical Biology; published by Springer. Used by permission.


Sexual reproduction in nature requires two sexes, which raises the question why the reproductive scheme did not evolve to have three or more sexes. Here we construct a constrained optimization model based on the communication theory to analyze trade-offs among reproductive schemes with arbitrary number of sexes. More sexes on one hand lead to higher reproductive diversity, but on the other hand incur greater cost in time and energy for reproductive success. Our model shows that the two-sexes reproduction scheme maximizes the recombination entropy-to-cost ratio, and hence is the optimal solution to the problem.