Gardner A, Reece S E, West S A
Institute of Cell, Animal and Population Biology, Ashworth Laboratories, University of Edinburgh, Edinburgh EH9 3JT, UK.
J Theor Biol. 2003 Aug 21;223(4):515-21. doi: 10.1016/s0022-5193(03)00142-5.
Theory developed for malaria and other protozoan parasites predicts that the evolutionarily stable gametocyte sex ratio (z*; proportion of gametocytes that are male) should be related to the inbreeding rate (f) by the equation z*=(1-f)/2. Although this equation has been applied with some success, it has been suggested that in some cases a less female biased sex ratio can be favoured to ensure female gametes are fertilized. Such fertility insurance can arise in response to two factors: (i) low numbers of gametes produced per gametocyte and (ii) the gametes of only a limited number of gametocytes being able to interact. However, previous theoretical studies have considered the influence of these two forms of fertility insurance separately. We use a stochastic analytical model to address this problem, and examine the consequences of when these two types of fertility insurance are allowed to occur simultaneously. Our results show that interactions between the two types of fertility insurance reduce the extent of female bias predicted in the sex ratio, suggesting that fertility insurance may be more important than has previously been assumed.
针对疟疾和其他原生动物寄生虫所发展出的理论预测，进化上稳定的配子体性别比（z*；雄性配子体的比例）应通过z*=(1-f)/2这一公式与近亲繁殖率（f）相关。尽管该公式已取得一定成功应用，但有人提出，在某些情况下，为确保雌配子受精，可能更倾向于选择偏差较小的雌性性别比。这种生育保障可因两个因素而产生：（i）每个配子体产生的配子数量少，以及（ii）只有有限数量的配子体的配子能够相互作用。然而，以往的理论研究分别考虑了这两种生育保障形式的影响。我们使用一个随机分析模型来解决这个问题，并研究当这两种生育保障类型同时出现时的后果。我们的结果表明，两种生育保障之间的相互作用降低了性别比中预测的雌性偏差程度，这表明生育保障可能比之前所认为的更为重要。
