Bogdziewicz Michał, Kelly Dave, Tanentzap Andrew J, Thomas Peter A, Lageard Jonathan G A, Hacket-Pain Andrew
Department of Systematic Zoology, Faculty of Biology, Adam Mickiewicz University, Umutlowska 89, 61-614 Poznan, Poland; CREAF, Universitat de Autonoma Barcelona, Cerdanyola del Valles, 08193 Catalonia, Spain.
Centre for Integrative Ecology, School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand.
Curr Biol. 2020 Sep 7;30(17):3477-3483.e2. doi: 10.1016/j.cub.2020.06.056. Epub 2020 Jul 9.
Climate change is altering patterns of seed production worldwide [1-4], but the potential for evolutionary responses to these changes is poorly understood. Masting (synchronous, annually variable seed production by plant populations) is selectively beneficial through economies of scale that decrease the cost of reproduction per surviving offspring [5-7]. Masting is particularly widespread in temperate trees [8, 9] impacting food webs, macronutrient cycling, carbon storage, and human disease risk [10-12], so understanding its response to climate change is important. Here, we analyze inter-individual variability in plant reproductive patterns and two economies of scale-predator satiation and pollination efficiency-and document how natural selection acting upon them favors masting. Four decades of observations for European beech (Fagus sylvatica) show that predator satiation and pollination efficiency select for individuals with higher inter-annual variability of reproduction and higher reproductive synchrony between individuals. This result confirms the long-standing theory that masting, a population-level phenomenon, is generated by selection on individuals. Furthermore, recent climate-driven increases in mean seed production have increased selection pressure from seed predators but not from pollination efficiency. Natural selection is thus acting to restore the fitness benefits of masting, which have previously decreased under a warming climate [13]. However, selection will likely take far longer (centuries) than climate warming (decades), so in the short-term, tree reproduction will be reduced because masting has become less effective at satiating seed predators. Over the long-term, evolutionary responses to climate change could potentially increase inter-annual variability of seed production of masting species.
气候变化正在改变全球种子生产模式[1 - 4]，但对这些变化的进化响应潜力却知之甚少。大年结实（植物种群同步、每年变化的种子生产）通过规模经济具有选择性优势，即降低每个存活后代的繁殖成本[5 - 7]。大年结实现象在温带树木中尤为普遍[8, 9]，影响着食物网、大量营养素循环、碳储存以及人类疾病风险[10 - 12]，因此了解其对气候变化的响应至关重要。在此，我们分析了植物繁殖模式中的个体间变异性以及两种规模经济——捕食者饱足和授粉效率，并记录了作用于它们的自然选择如何有利于大年结实。对欧洲山毛榉（Fagus sylvatica）长达四十年的观察表明，捕食者饱足和授粉效率选择了繁殖年际变异性较高且个体间繁殖同步性较高的个体。这一结果证实了长期以来的理论，即大年结实作为一种种群水平的现象，是由对个体的选择产生的。此外，近期由气候驱动的平均种子产量增加，增加了来自种子捕食者而非授粉效率的选择压力。因此，自然选择正在恢复大年结实的适应性益处，而在气候变暖的情况下，这种益处此前已经降低[13]。然而，选择可能需要比气候变暖（数十年）长得多的时间（数百年），所以在短期内，树木繁殖将会减少，因为大年结实对种子捕食者的饱腹作用变得不那么有效了。从长期来看，对气候变化的进化响应可能会增加大年结实物种种子生产的年际变异性。
