Harvest-induced phenotypic selection in an island population of moose, Alces alces

Empirical evidence strongly indicates that human exploitation has frequently led to rapid evolutionary changes in wild populations, yet the mechanisms involved are often poorly understood. Here we applied a recently developed demographic framework for analysing selection to data from a 20-year study of a wild population of moose, Alces alces. In this population, a genetic pedigree has been established all the way back to founders. We demonstrate harvest-induced directional selection for delayed birth dates in males and reduced body mass as calf in females. During the study period, birth date was delayed by 0.81 days per year for both sexes, while no significant changes occurred in calf body mass. Quantitative genetic analyses indicated that both traits harboured significant additive genetic variance. These results show that selective harvesting can induce strong selection which oppose natural selection. This may cause evolution of less favourable phenotypes that become maladaptive once harvesting ceases.

大量实证证据表明，人类开发活动常会导致野生种群发生快速演化，但其中涉及的演化机制往往仍未得到充分阐释。本研究将新近开发的种群统计分析框架应用于一项针对野生驼鹿（Alces alces）种群长达20年的研究数据。该种群已建立起可追溯至奠基个体的完整遗传谱系。研究结果显示，狩猎收获诱导了雄性延迟产仔日期、雌性幼崽体重降低的定向选择。在本研究周期内，两性个体的产仔日期均以每年0.81天的速率延迟，而幼崽体重未出现显著变化。数量遗传学分析表明，这两个性状均存在显著的加性遗传方差。上述结果证实，选择性收获可引发与自然选择方向相反的强选择作用，这可能会导致产生适应性欠佳的表型，一旦收获活动停止，这些表型便会成为适应不良的性状。