Sexual allocation in hermaphroditic plants

为了解释两性植物中偏向雌性的性别分配，我们建立了一个包含花/果实生长的源-库关系的博弈论模型。在该模型中，花/果的生长速度要么受其库强度(潜在的相对生长率和绝对大小的乘积)的限制，要么受植物的源强度(生殖资源的供给率)的限制。我们证明，如果果实的生长是库限制的，那么偏向女性的性别分配在进化上是稳定的，至少在其生长的早期阶段是这样。如果生殖资源的供给率相对于潜在的相对增长率较大，那么女性偏见的程度就会很强。如果产生一个种子的相对成本与产生一个胚珠的相对成本相比较大，那么雌性偏见的程度也很强，这与以前的有性分配模式相反，在这种模式中，性别分配比与产生一个胚珠和一个种子的成本无关。因此，果实生长的下沉限制可能是在两性植物中观察到的偏向雌性的有性分配的一般因素，而不考虑它们的交配系统。

To explain female-biased sexual allocation in cosexual plants, we developed a game theoretic model incorporating a source-sink relationship of flower/fruit growth. In this model, flower/fruit growth rate is either limited by its sink strength (the product of its potential relative growth rate and absolute size) or by the source strength (supply rate of reproductive resources) of the plant. We show that female-biased sexual allocation is evolutionarily stable if fruit growth is sink-limited at least in the early stage of its growth. The degree of female-bias is strong if the supply rate of reproductive resources is large relative to the potential relative growth rate. The degree of female-bias is also strong if the relative cost of producing one seed as compared with that of producing one ovule is large, in contrast to the previous sexual allocation models, in which the sexual allocation ratio is independent of the costs of producing one ovule and one seed. Thus, sink-limitation of fruit growth can be a general factor that selects for female-biased sexual allocation observed in cosexual plants irrespective of their mating systems.