Department of Earth Sciences, University of Oxford, OX1 3AN Oxford, United Kingdom,
Department of Earth Sciences, University of Oxford, OX1 3AN Oxford, United Kingdom.
Proc Natl Acad Sci U S A. 2021 May 4;118(18). doi: 10.1073/pnas.2017105118.
Abiotic niche lability reduces extinction risk by allowing species to adapt to changing environmental conditions in situ. In contrast, species with static niches must keep pace with the velocity of climate change as they track suitable habitat. The rate and frequency of niche lability have been studied on human timescales (months to decades) and geological timescales (millions of years), but lability on intermediate timescales (millennia) remains largely uninvestigated. Here, we quantified abiotic niche lability at 8-ka resolution across the last 700 ka of glacial-interglacial climate fluctuations, using the exceptionally well-known fossil record of planktonic foraminifera coupled with Atmosphere-Ocean Global Climate Model reconstructions of paleoclimate. We tracked foraminiferal niches through time along the univariate axis of mean annual temperature, measured both at the sea surface and at species' depth habitats. Species' temperature preferences were uncoupled from the global temperature regime, undermining a hypothesis of local adaptation to changing environmental conditions. Furthermore, intraspecific niches were equally similar through time, regardless of climate change magnitude on short timescales (8 ka) and across contrasts of glacial and interglacial extremes. Evolutionary trait models fitted to time series of occupied temperature values supported widespread niche stasis above randomly wandering or directional change. Ecotype explained little variation in species-level differences in niche lability after accounting for evolutionary relatedness. Together, these results suggest that warming and ocean acidification over the next hundreds to thousands of years could redistribute and reduce populations of foraminifera and other calcifying plankton, which are primary components of marine food webs and biogeochemical cycles.
非生物生态位不稳定性通过允许物种在原地适应不断变化的环境条件，从而降低了灭绝风险。相比之下，具有静态生态位的物种必须跟上气候变化的速度，因为它们需要跟踪适合的栖息地。生态位不稳定性的速度和频率已经在人类时间尺度（数月至数十年）和地质时间尺度（数百万年）上进行了研究，但在中间时间尺度（千年）上的不稳定性仍然在很大程度上没有被研究过。在这里，我们使用浮游有孔虫异常详细的化石记录和大气-海洋全球气候模型对古气候的重建，在过去 70 万年的冰期-间冰期气候波动中，以 8 千年的分辨率量化了非生物生态位不稳定性。我们通过时间追踪有孔虫的生态位，沿着年均温度的单变量轴，在海面和物种深度栖息地都进行了测量。物种的温度偏好与全球温度模式脱钩，破坏了对环境变化的局部适应的假设。此外，无论在 8 千年的短时间尺度上气候变化幅度如何，或者跨越冰期和间冰期的极端情况，种内生态位在时间上都是相似的。适应进化的特征模型拟合了占据温度值的时间序列，支持了广泛的生态位稳定，而不是随机游走或定向变化。在考虑到进化亲缘关系后，生态型仅能解释物种水平生态位不稳定性差异中的一小部分变异。总的来说，这些结果表明，在未来数百年到数千年内，变暖以及海洋酸化可能会重新分配和减少有孔虫和其他钙化浮游生物的数量，这些生物是海洋食物网和生物地球化学循环的主要组成部分。
