Should mothers in poor condition invest more in daughter than in son?

摘要

Although TRIVERS & WILLARD (1973) model is among the most influential ideas in evolutionary ecology, some of its predictions are subject of controversies. On one hand the prediction that mothers in poor condition should produce more daughters while those in good condition should produce sons is generally accepted and reasonably well supported. On the other hand, it is not clear how maternal condition should affect subsequent investment into the two sexes. Using graphical model and simple simulation Ishow here that mothers in poor condition should invest more in daughters. I point out further that the continuing confusion around the predictions of the model is caused partly by imprecise formulation in the original TRIVERS & WILLARD (1973) paper andpartly by poor discrimination of researchers between current value of the progeny versus the marginal returns from additional investment.