Portnoy David S, Piercy Andrew N, Musick John A, Burgess George H, Graves John E
Virginia Institute of Marine Science, College of William and Mary, PO Box 1346, Gloucester Point, VA 23062-1346, USA.
Mol Ecol. 2007 Jan;16(1):187-97. doi: 10.1111/j.1365-294X.2006.03138.x.
To investigate patterns of polyandry in the sandbar shark (Carcharhinus plumbeus), 20 pregnant females were sampled from the western North Atlantic and Gulf of Mexico. Five species-specific microsatellite markers were used to genotype each shark and its litter. Of 20 litters, 17 (85%) were shown to have multiple sires. In multiply sired litters, the estimated minimum number of sires ranged from two to five with an average of 2.3 males per litter. Regression analysis did not demonstrate a significant relationship between female reproductive success and female body size or sire number and female body size. There was a high incidence of reproductive skew noted in litters, and two groups of males with significantly different mean reproductive success were observed. Analyses using Bateman's principles suggest that there is less direct benefit for females that acquire multiple mates than for males who bias paternity within litters. In light of past morphological and behavioural studies, these data suggest that patterns of polyandry in elasmobranchs may be determined by coercive mating, and that breeding behaviour has likely evolved in the context of sexual conflict.
为了研究沙虎鲨（Carcharhinus plumbeus）的一妻多夫模式，从北大西洋西部和墨西哥湾采集了20头怀孕雌鲨样本。使用5种物种特异性微卫星标记对每头鲨鱼及其幼崽进行基因分型。在20窝幼崽中，有17窝（85%）被证明有多个父亲。在多父系幼崽中，估计父亲的最小数量为2至5个，每窝平均有2.3只雄性。回归分析未显示雌性繁殖成功率与雌性体型或父本数量与雌性体型之间存在显著关系。在幼崽中观察到繁殖偏斜的发生率很高，并且观察到两组雄性的平均繁殖成功率存在显著差异。使用贝特曼原理的分析表明，与在幼崽中偏向父权的雄性相比，获得多个配偶的雌性获得的直接益处较少。根据过去的形态学和行为学研究，这些数据表明，软骨鱼类的一妻多夫模式可能由强制性交配决定，并且繁殖行为可能在性冲突的背景下进化而来。
