WHY ARE THERE SO MANY TINY SPERM - SPERM COMPETITION AND THE MAINTENANCE OF 2 SEXES
WHY ARE THERE SO MANY TINY SPERM - SPERM COMPETITION AND THE MAINTENANCE OF 2 SEXES
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DOI：
10.1016/0022-5193(82)90225-9
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发表时间：
1982-01-01
影响因子：
2
通讯作者：
PARKER, GA
中科院分区：
文献类型：
--
作者：
PARKER, GA
精子竞争（两个或两个以上雄性的精子之间对卵子受精的竞争）可以解释精子如此之小和如此之多的事实。在完全没有精子竞争的情况下，选择可能有利于精子大小的增加，以便精子为随后的受精卵的存活和成功提供营养。极低的精子竞争发生率足以防止精子大小增加。脊椎动物的精子应该保持在最小的尺寸，只要双交配（1只雌性与2只雄性交配）发生的频率超过精子尺寸：卵子尺寸之比的4倍。经典理论认为，精子之所以小，仅仅是因为难以确保卵子受精，这也可以解释精子的大小，这两种效应（精子竞争和确保受精）都可能有助于异配生殖的稳定性。大量的精子可以产生，因为精子很小，即使在双交配相当罕见的情况下，射精的生殖储备的最佳分配也不是微不足道的。雄性脊椎动物在交配过程中，花在精子上的时间只占其总交配努力的一小部分，大约相当于双交配概率的四分之一。
Sperm competition (competition between the sperm from 2 or more males over the fertilization of ova) may account for the fact that sperm are so small and so numerous. In the entire absence of sperm competition, selection may favor an increase in sperm size so that the sperm contributes nutriment to the subsequent viability and success of the zygote. An extremely low incidence of sperm competition is adequate to prevent sperm size increasing. Vertebrate sperm should remain at minimal size provided that double matings (1 female mated by 2 males) occur more often than about 4 times the ratio of sperm size: ovum size. The classical theory that sperm are small simply because of the difficulties of ensuring that ova do get fertilized may also explain sperm size, and both effects (sperm competition and ensuring fertilization) are likely to contribute to the stability of anisogamy. Large numbers of sperm can be produced because sperm are tiny and the optimal allocation of reproductive reserves to ejaculates is not trivially small even when double matings are rather rare. Of its total mating effort, a male vertebrate should spend a fraction on sperm that is roughly equivalent to a quarter of the probability of double mating.