Data from: Population growth in a wild bird is buffered against phenological mismatch

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.大范围的环境变化正在改变野外自然选择的作用模式，但目前鲜有实证研究量化了响应此类环境变化的持续定向选择所带来的种群统计学成本。本研究基于某大山雀（great tit）种群近四十年的个体水平生活史数据，检验了气候变化引发的物候错配（phenological mismatch）是否会对野生鸟类的种群增长产生负面影响。在该种群中，春季气温升高使得年度繁殖时间与季节性食物峰值出现错配，进而强化了对更早产卵的定向选择压力。然而，该种群内物候错配的年际波动并未对种群增长产生影响。本研究揭示了促成这一解耦现象的潜在机制：由竞争缓解带来的适合度增益抵消了物候错配所导致的适合度损失。上述研究结果表明，自然种群或可耐受气候变化驱动的显著适应性失调，而不会立即出现种群衰退。