Broquet Thomas, Jaquiéry Julie, Perrin Nicolas
Department of Ecology and Evolution, University of Lausanne, CH-1015 Lausanne, Switzerland.
Evolution. 2009 Mar;63(3):674-83. doi: 10.1111/j.1558-5646.2008.00586.x.
Sexual selection in lek-breeding species might drastically lower male effective population size, with potentially important consequences for evolutionary and conservation biology. Using field-monitoring and parental-assignment methods, we analyzed sex-specific variances in breeding success in a population of European treefrogs, to (1) help understanding the dynamics of genetic variance at sex-specific loci, and (2) better quantify the risk posed by genetic drift in this species locally endangered by habitat fragmentation. The variance in male mating success turned out to be markedly lower than values obtained from other amphibian species with polygamous mating systems. The ratio of effective breeding size to census breeding size was only slightly lower in males (0.44) than in females (0.57), in line with the patterns of genetic diversity previously reported from H. arborea sex chromosomes. Combining our results with data on age at maturity and adult survival, we show that the negative effect of the mating system is furthermore compensated by the effect of delayed maturity, so that the estimated instantaneous effective size broadly corresponded to census breeding size. We conclude that the lek-breeding system of treefrogs impacts only weakly the patterns of genetic diversity on sex-linked genes and the ability of natural populations to resist genetic drift.
在求偶场繁殖的物种中，性选择可能会大幅降低雄性的有效种群大小，这对进化生物学和保护生物学可能具有重要影响。我们运用野外监测和亲子关系鉴定方法，分析了欧洲树蛙种群中繁殖成功率的性别特异性差异，以（1）帮助理解性别特异性位点的遗传变异动态，以及（2）更好地量化遗传漂变对这种因栖息地破碎化而局部濒危的物种所构成的风险。结果表明，雄性交配成功率的方差显著低于从其他具有多配偶交配系统的两栖动物物种中获得的值。有效繁殖规模与普查繁殖规模的比率，雄性（0.44）仅略低于雌性（0.57），这与之前从欧洲树蛙性染色体报道的遗传多样性模式一致。将我们的结果与成熟年龄和成年存活率的数据相结合，我们发现交配系统的负面影响进一步被延迟成熟的影响所补偿，因此估计的瞬时有效规模大致与普查繁殖规模相符。我们得出结论，树蛙的求偶场繁殖系统对性连锁基因上遗传多样性的模式以及自然种群抵抗遗传漂变的能力影响较弱。
