Department of Animal Ecology, Netherland Institute of Ecology (NIOO-KNAW), 6708 PB Wageningen, The Netherlands
Department of Animal Ecology, Netherland Institute of Ecology (NIOO-KNAW), 6708 PB Wageningen, The Netherlands.
J Exp Biol. 2020 Apr 23;223(Pt 8):jeb218784. doi: 10.1242/jeb.218784.
Phenotypic plasticity is an important mechanism by which an individual can adapt its seasonal timing to predictable, short-term environmental changes by using predictive cues. Identification of these cues is crucial to forecast the response of species to long-term environmental change and to study their potential to adapt. Individual great tits () start reproduction early under warmer conditions in the wild, but whether this effect is causal is not well known. We housed 36 pairs of great tits in climate-controlled aviaries and 40 pairs in outdoor aviaries, where they bred under artificial contrasting temperature treatments or in semi-natural conditions, respectively, for two consecutive years, using birds from lines selected for early and late egg laying. We thus obtained laying dates in two different thermal environments for each female. Females bred earlier under warmer conditions in climate-controlled aviaries, but not in outdoor aviaries. The latter was inconsistent with laying dates from our wild population. Further, early selection line females initiated egg laying consistently ∼9 days earlier than late selection line females in outdoor aviaries, but we found no difference in the degree of plasticity (i.e. the sensitivity to temperature) in laying date between selection lines. Because we found that temperature causally affects laying date, climate change will lead to earlier laying. This advancement is, however, unlikely to be sufficient, thereby leading to selection for earlier laying. Our results suggest that natural selection may lead to a change in mean phenotype, but not to a change in the sensitivity of laying dates to temperature.
表型可塑性是一种重要的机制，通过这种机制，个体可以利用预测线索来适应可预测的短期环境变化，从而调整其季节性时间安排。识别这些线索对于预测物种对长期环境变化的反应以及研究它们的适应潜力至关重要。在野外条件下，个体大山雀在温暖的条件下会更早地开始繁殖，但这种影响是否具有因果关系尚不清楚。我们将 36 对大山雀饲养在气候控制的鸟舍中，将 40 对饲养在户外鸟舍中，在这两个环境中，它们分别在人工对比温度处理或半自然条件下繁殖了两年，使用的是早期和晚期产卵的品系的鸟类。因此，我们为每只雌鸟获得了两种不同热环境下的产卵日期。在气候控制的鸟舍中，雌性在温暖的条件下繁殖更早，但在户外鸟舍中则不然。这与我们的野生种群中的产卵日期不一致。此外，在户外鸟舍中，早期选择线的雌性比晚期选择线的雌性早约 9 天开始产卵，但我们没有发现选择线之间在产卵日期上的可塑性（即对温度的敏感性）存在差异。由于我们发现温度会影响产卵日期，因此气候变化将导致更早的产卵。然而，这种提前不太可能足以导致更早的产卵选择。我们的研究结果表明，自然选择可能导致平均表型发生变化，但不会导致产卵日期对温度的敏感性发生变化。
