Johnston M O, Das B, Hoeh W R
Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada.
Proc Natl Acad Sci U S A. 1998 Jan 20;95(2):617-20. doi: 10.1073/pnas.95.2.617.
Sex-allocation theory predicts that the evolution of increased rates of self-fertilization should be accompanied by decreased allocation to male reproduction (sperm production and broadcast). This prediction has found support in plants but has not previously been tested in animals, which, in contrast to biotically pollinated plants, are free of complications associated with incorporating the costs of attractive structures such as petals. Here we report rates of self-fertilization as well as proportional allocation to male reproductive tissues within populations of the simultaneous hermaphrodite Utterbackia imbecillis, a freshwater mussel. Individuals from populations with higher selfing rates devoted a lower proportion of reproductive tissue to sperm production (correlation = -0.99), in support of theory.
性别分配理论预测，自体受精率上升的进化过程应伴随着对雄性繁殖（精子产生和散播）分配的减少。这一预测在植物中得到了支持，但此前尚未在动物中得到验证。与靠生物传粉的植物不同，动物不存在与纳入诸如花瓣等吸引结构成本相关的复杂情况。在此，我们报告了淡水贻贝——同时具有雌雄两性的柔弱无齿蚌种群中的自体受精率以及对雄性生殖组织的比例分配情况。来自自体受精率较高种群的个体，其生殖组织中用于精子产生的比例较低（相关性 = -0.99），这支持了该理论。
