Marino Ilaria A M, Riginella Emilio, Gristina Michele, Rasotto Maria B, Zane Lorenzo, Mazzoldi Carlotta
Department of Biology, University of Padova, Via U. Bassi 58/B, 35121 Padova, Italy.
IAMC-CNR, via Luigi Vaccara 61, 91026 Mazara del Vallo (TP), Italy.
Sci Rep. 2015 Aug 10;5:12919. doi: 10.1038/srep12919.
Multiple paternity appears to be a common trait of elasmobranch mating systems, with its occurrence likely driven by convenience, due to females seeking to minimize the stress of male harassment. Here we use molecular markers to analyse the frequency of multiple paternity in two related viviparous sharks, Mustelus mustelus and Mustelus punctulatus. We first applied molecular methods to assign pregnant females, embryos and additional reference adults (N = 792) to one of the two species. Paternity analysis was performed using a total of 9 polymorphic microsatellites on 19 females and 204 embryos of M. mustelus, and on 13 females and 303 embryos of M. punctulatus. Multiple paternity occurs in both species, with 47% of M. mustelus and 54% of M. punctulatus litters sired by at least two fathers. Female fecundity is not influenced by multiple mating and in 56% of polyandrous litters paternity is skewed, with one male siring most of the pups. Genetic analyses also revealed hybridization between the two species, with a M. punctulatus female bearing pups sired by a M. mustelus male. The frequency of polyandrous litters in these species is consistent with aspects of their reproductive biology, such as synchronous ovulation and possible occurrence of breeding aggregations.
多重父权现象似乎是板鳃亚纲动物交配系统的一个常见特征，其出现可能是出于便利，因为雌性试图将雄性骚扰带来的压力降至最低。在此，我们使用分子标记来分析两种相关的胎生鲨鱼——条纹斑竹鲨和斑点星鲨——中多重父权的频率。我们首先应用分子方法将怀孕的雌性、胚胎以及其他参考成年个体（N = 792）归为这两个物种中的一个。使用总共9个多态微卫星对19只条纹斑竹鲨雌性和204个胚胎，以及13只斑点星鲨雌性和303个胚胎进行了父权分析。两个物种中均出现了多重父权现象，条纹斑竹鲨有47%的窝仔、斑点星鲨有54%的窝仔是由至少两个父亲所生。雌性的繁殖力不受多次交配的影响，在56%的一妻多夫制窝仔中，父权存在偏倚，即一只雄性使大多数幼崽受孕。遗传分析还揭示了这两个物种之间的杂交现象，一只斑点星鲨雌性产下的幼崽是由一只条纹斑竹鲨雄性授精的。这些物种中一妻多夫制窝仔的频率与它们生殖生物学的一些方面相符，比如同步排卵以及可能出现的繁殖群体。
