Jones M W, Hutchings J A
Department of Biology, Dalhousie University, Halifax, Nova Scotia B3H 4 J1, Canada.
Heredity (Edinb). 2001 Jun;86(Pt 6):675-84. doi: 10.1046/j.1365-2540.2001.00880.x.
Alternative mating strategies in male Atlantic salmon, Salmo salar, are characterized by variability in body size and mate competition. Controlling breeding numbers of larger, older anadromous males, we examined whether body size of mature male parr influenced fertilization success and whether such an association was affected by mate competition among parr. Variation at three to four hypervariable microsatellite loci was used to determine individual paternity of 53-60 offspring from two or three nests from each experimental treatment. Although individual and total parr reproductive success differed significantly among nests within treatments, there was no relationship between parr size and individual reproductive success at any level of competition when anadromous males were involved. However, in a single treatment having no anadromous male, the influence of body size on parr fertilization success was highly significant. Combining data from all treatments, parr body size was an important predictor of the probability of an individual being involved in spawning. We found a negative relationship between total parr reproductive success and intensity of anadromous male competition. To our knowledge, the present study is the first to estimate the effective number of males from individual fertilization success in fish. Our estimates of Ne should not be taken as absolute and may have a downward bias because we did not sample all nests and we used a proxy for lifetime reproductive success. They do, however, illustrate how mature male parr can greatly increase the effective number of males when the latter is estimated from anadromous individuals alone. Although reproductive success by mature male parr increases the effective number of males, this increase seems likely to be most pronounced in natural populations when the number of anadromous males is low.
雄性大西洋鲑（Salmo salar）的替代交配策略具有体型差异和配偶竞争的特点。通过控制体型较大、年龄较大的溯河洄游雄性的繁殖数量，我们研究了成熟雄性幼鲑的体型是否会影响受精成功率，以及这种关联是否会受到幼鲑之间配偶竞争的影响。利用三到四个高变微卫星位点的变异来确定每个实验处理中来自两到三个巢穴的53 - 60只后代的个体父系。尽管在处理组内的巢穴之间，个体和幼鲑的总繁殖成功率存在显著差异，但当涉及溯河洄游雄性时，在任何竞争水平下，幼鲑体型与个体繁殖成功率之间均无关联。然而，在一个没有溯河洄游雄性的单一处理中，体型对幼鲑受精成功率的影响非常显著。综合所有处理的数据，幼鲑体型是个体参与产卵概率的重要预测指标。我们发现幼鲑的总繁殖成功率与溯河洄游雄性的竞争强度之间呈负相关。据我们所知，本研究是首次从鱼类个体受精成功率来估计有效雄性数量。我们对有效种群数量（Ne）的估计不应被视为绝对的，可能存在向下偏差，因为我们没有对所有巢穴进行采样，并且我们使用了一个终身繁殖成功率的替代指标。然而，它们确实说明了当仅从溯河洄游个体估计有效雄性数量时，成熟雄性幼鲑如何能够大大增加有效雄性数量。尽管成熟雄性幼鲑的繁殖成功率增加了有效雄性数量，但当溯河洄游雄性数量较低时，这种增加在自然种群中可能最为明显。
