Jones Adam G, Avise John C
Department of Genetics, University of Georgia, Athens, Georgia, 30602.
Evolution. 1997 Oct;51(5):1611-1622. doi: 10.1111/j.1558-5646.1997.tb01484.x.
In the dusky pipefish Syngnathus floridae, like other species in the family Syngnathidae, 'pregnant' males provide all post-zygotic care. Male pregnancy has interesting implications for sexual selection theory and the evolution of mating systems. Here, we employ microsatellite markers to describe the genetic mating system of S. floridae, compare the outcome with a previous report of genetic polyandry for the Gulf pipefish S. scovelli, and consider possible associations between the mating system and degree of sexual dimorphism in these species. Twenty-two pregnant male dusky pipefish from one locale in the northern Gulf of Mexico were analyzed genetically, together with subsamples of 42 embryos from each male's brood pouch. Adult females also were assayed. The genotypes observed in these samples document that cuckoldry by males did not occur; males often receive eggs from multiple females during the course of a pregnancy (six males had one mate each, 13 had two mates, and three had three mates); embryos from different females are segregated spatially within a male's brood pouch; and a female's clutch of eggs often is divided among more than one male. Thus, the genetic mating system of the dusky pipefish is best described as polygynandrous. The genetic results for S. floridae and S. scovelli are consistent with a simple model of sexual selection which predicts that for sex role-reversed organisms, species with greater degrees of sexual dimorphism are more highly polyandrous.
在暗斑尖鼻鱼（Syngnathus floridae）中，与尖嘴鱼科的其他物种一样，“怀孕”的雄性承担所有合子后的养育工作。雄性怀孕对性选择理论和交配系统的进化具有有趣的启示。在此，我们使用微卫星标记来描述暗斑尖鼻鱼的遗传交配系统，将结果与先前关于海湾尖嘴鱼（Syngnathus scovelli）遗传一妻多夫制的报告进行比较，并考虑这些物种的交配系统与两性异形程度之间可能存在的关联。对来自墨西哥湾北部一个地点的22只怀孕的雄性暗斑尖鼻鱼进行了遗传分析，同时对每只雄性育儿袋中的42个胚胎子样本也进行了分析。还对成年雌性进行了检测。在这些样本中观察到的基因型表明雄性没有发生戴绿帽现象；雄性在怀孕过程中经常从多个雌性那里接收卵子（6只雄性各有一个配偶，13只有两个配偶，3只有三个配偶）；来自不同雌性的胚胎在雄性的育儿袋内空间上是分开的；并且雌性的一窝卵通常会分给不止一只雄性。因此，暗斑尖鼻鱼的遗传交配系统最好描述为多雌多雄制。暗斑尖鼻鱼和海湾尖嘴鱼的遗传结果与一个简单的性选择模型一致，该模型预测对于性别角色反转的生物，两性异形程度较高的物种一妻多夫的程度也更高。
