Department of Animal Ecology, Netherlands Institute of Ecology, Wageningen, Netherlands.
Science. 2013 Apr 26;340(6131):488-91. doi: 10.1126/science.1232870.
Broad-scale environmental changes are altering patterns of natural selection in the wild, but few empirical studies have quantified the demographic cost of sustained directional selection in response to these changes. We tested whether population growth in a wild bird is negatively affected by climate change-induced phenological mismatch, using almost four decades of individual-level life-history data from a great tit population. In this population, warmer springs have generated a mismatch between the annual breeding time and the seasonal food peak, intensifying directional selection for earlier laying dates. Interannual variation in population mismatch has not, however, affected population growth. We demonstrated a mechanism contributing to this uncoupling, whereby fitness losses associated with mismatch are counteracted by fitness gains due to relaxed competition. These findings imply that natural populations may be able to tolerate considerable maladaptation driven by shifting climatic conditions without undergoing immediate declines.
大规模的环境变化正在改变野外自然选择的模式，但很少有实证研究量化了为应对这些变化而持续进行定向选择的人口成本。我们利用一个大山雀种群近四十年的个体水平生活史数据，测试了气候变化引起的物候不匹配是否会对野生鸟类的种群增长产生负面影响。在这个种群中，温暖的春天导致了年度繁殖时间和季节性食物高峰之间的不匹配，加剧了对更早产卵日期的定向选择。然而，种群不匹配的年际变化并没有影响种群的增长。我们证明了一种促成这种解耦的机制，即不匹配相关的适应不良损失被竞争放松带来的适应良好收益所抵消。这些发现意味着，自然种群可能能够在不立即下降的情况下，容忍由气候变化引起的相当大的不适。
