Comparing fecundity in parthenogenetic versus sexual populations of the freshwater snail Campeloma limum: is there a two‐fold cost of sex?
Comparing fecundity in parthenogenetic versus sexual populations of the freshwater snail Campeloma limum: is there a two‐fold cost of sex?
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比较淡水蜗牛 Campeloma limum 的孤雌生殖与有性生殖种群的繁殖力：是否存在两倍的性成本？
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
M. Wayne
中科院分区：
文献类型：
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作者：
Lisa T Crummett;M. Wayne
。考虑到“性行为的双重代价”，也就是众所周知的“雄性代价”，真核生物中性行为的主导地位仍然是进化上的悖论。[更正：在2009年1月29日网上发布后，删除了前一句中的无关词。]由于它需要两个有性行为的父母生育，而且只需要一个孤雌生殖父母，如果其他条件相同，孤雌生殖的生殖率应该是他们的有性伴侣的两倍，他们的基因传播的速度应该是他们的两倍。然而，孤雌生殖相对罕见，被认为是进化的死胡同，而有性繁殖是多细胞真核生物的主要繁殖形式。许多研究探索了性行为的短期好处，这些好处可能会超过性行为的两倍成本，但很少有研究比较近亲性行为和单性生殖之间的繁殖力，以首先验证“其他条件都是平等的”生殖。我们比较了淡水蜗牛有性生殖和孤雌生殖种群在两个水系的孵化周期(1年)内的6种生殖指标。由于排水效果显著，因此分别对排水进行了分析。在萨凡纳排水系统中，雌雄生殖能力没有显著差异，尽管单性生殖个体每窝有明显更多的空卵壳。在Ogeechee排水系统中，单性生殖个体的卵囊中多个胚胎和孵化的胚胎数量显著多于雌性个体。在超过1年的时间内，单性生殖和性别之间的胚胎大小在两种引流方式中都没有显著差异。考虑到这些结果以及有性生殖和孤雌生殖种群的紧密联系，为什么孤雌生殖种群没有完全取代有性生殖种群，这是令人困惑的。
. The predominance of sexuality in eukaryotes remains an evolutionary paradox, given the “two-fold cost of sex” also known as the “cost of males.” [Correction added after online publication 29 January 2009: in the preceding sentence, extraneous words were deleted.] As it requires two sexual parents to reproduce and only one parthenogenetic parent, parthenogens should have twice the reproductive rate compared with their sexual counterparts and their genes should spread twice as fast, if all else is equal. Yet, parthenogenesis is relatively rare and considered an evolutionary dead-end, while sexuality is the dominant form of reproduction in multicellular eukaryotes. Many studies have explored short-term benefits of sex that could outweigh its two-fold cost, but few have compared fecundity between closely related sexuals and parthenogens to first verify that “all else is equal” reproductively. We compared six fecundity measures between sexual and parthenogenetic populations of the freshwater snail, Campeloma limum, during a brooding cycle (1 year) across two drainages. Drainages were analyzed separately because of a significant drainage effect. In the Savannah drainage, fecundity was not significantly different between sexuals and parthenogens, even though parthenogens had significantly more empty egg capsules per brood. In the Ogeechee drainage, parthenogens had significantly more egg capsules with multiple embryos and more hatched embryos than sexuals. Taken over 1 year, embryo size was not significantly different between parthenogens and sexuals in either drainage. Given these results and the close proximity of sexual and parthenogenetic populations, it is perplexing why parthenogenetic populations have not completely replaced sexual populations in C. limum.