Department of Ichthyology and Fisheries Science, Rhodes University, Grahamstown, South Africa.
National Research Foundation-South African Institute for Aquatic Biodiversity (NRF-SAIAB), South Africa.
J Hered. 2019 May 7;110(3):351-360. doi: 10.1093/jhered/esz008.
A critical part of the sexual selection process in animals is the genetic mating system. Quantifying mating systems, especially in species with cryptic life histories can be challenging. One approach is to use genotypic markers and accurate parentage analysis, along with methods to account for bias when sampling natural populations, to calculate sexual selection metrics derived from Bateman's principles. In this study, 3 microsatellites were used to genotype 48 adults (23 female and 25 male) and 342 offspring from known mothers of live-bearing bluntnose klipfish. Parentage analysis was performed to interpret mating and reproductive success for both sexes. Metrics quantified were the opportunity for selection (I), the opportunity for sexual selection (Is), absolute (βss), and standardized (β'ss) Bateman gradients and the maximum intensity of precopulatory sexual selection (s'max). Multiple mating by both sexes were revealed by parentage analysis. However, females did not show significant Bateman gradients or a significant maximum intensity of precopulatory sexual selection (s'max), whereas male sexual selection metrics were all significantly greater than 0. These results suggest a polygynandrous mating system for this species. There is an opportunity for sexual selection to act on males but not females in this population, which is evolutionary tied to anisogamy, parental investment, and sex roles.
动物的性选择过程的一个关键部分是遗传交配系统。量化交配系统，特别是在具有隐蔽生活史的物种中，可能具有挑战性。一种方法是使用基因型标记和准确的亲子分析，以及在对自然种群进行采样时考虑偏差的方法，根据 Bateman 原则计算来自性选择的度量。在这项研究中，使用 3 个微卫星标记对 48 个成年个体（23 个雌性和 25 个雄性）和已知胎生钝吻鱥的 342 个已知母亲的后代进行基因分型。亲子分析用于解释两性的交配和生殖成功。量化的指标是选择机会（I）、性选择机会（Is）、绝对（βss）和标准化（β'ss）Bateman 梯度以及前交配性选择的最大强度（s'max）。亲子分析揭示了两性的多次交配。然而，雌性没有表现出显著的 Bateman 梯度或前交配性选择的显著最大强度（s'max），而雄性的性选择指标都显著大于 0。这些结果表明该物种存在一妻多夫的交配系统。在这个种群中，雄性有机会进行性选择，但雌性没有，这与雌雄配子大小差异、亲代投资和性别角色有关。
