Persistent ecological shifts in marine molluscan assemblages across the end-Cretaceous mass extinction
Persistent ecological shifts in marine molluscan assemblages across the end-Cretaceous mass extinction
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DOI：
10.1073/pnas.1422248112
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发表时间：
2015-06-09
影响因子：
11.1
通讯作者：
Kiessling, Wolfgang
中科院分区：
文献类型：
--
作者：
Aberhan, Martin;Kiessling, Wolfgang
当代生物多样性的丧失和人口的减少有可能将生物圈推向一个临界点，对生态系统的组成和功能产生不可逆转的影响。作为过去地质历史中全球范围制度转变的一个潜在例子，我们基于四个研究充分的地点的软体动物组合，评估了白垩纪末大灭绝期间的生态变化。通过对比灭绝前和灭绝后的等级丰度和19种软体动物生命模式的数量丰度-每种模式被定义为流动性水平、摄食模式和相对于底物的位置的独特组合-我们发现生态空间利用率发生了明显的变化，大大超过了零模型的预测。在遥远的地点，相对于正常时间波动的功能特征的变化幅度表明，软体动物的组合向不同结构的系统转移，动物群的反应是全球性的。然而，时间生态变化的强度大多在灭绝前地点到地点的变异范围内，表明局部生态周转与广泛纬度范围内的地理变化相似。结合个体生命模式不同地点特定时间模式的不同，这些空间和时间上的异质性反对软体动物组合从一个明确的区域到另一个区域的一致相移。相比之下，在更广泛的生态层面上，出现了一致的趋势，并暗示了确定性的过程。这些模式包括众所周知的灭绝后群落中以沉积物为食的软体动物的增加，以及捕食者和抵抗捕食者的生活方式的增加，即以提高机动性和非动物群生活习性为特征的生活方式的增加。
Contemporary biodiversity loss and population declines threaten to push the biosphere toward a tipping point with irreversible effects on ecosystem composition and function. As a potential example of a global-scale regime shift in the geological past, we assessed ecological changes across the end-Cretaceous mass extinction based on molluscan assemblages at four well-studied sites. By contrasting preextinction and postextinction rank abundance and numerical abundance in 19 molluscan modes of life-each defined as a unique combination of mobility level, feeding mode, and position relative to the substrate-we find distinct shifts in ecospace utilization, which significantly exceed predictions from null models. The magnitude of change in functional traits relative to normal temporal fluctuations at far-flung sites indicates that molluscan assemblages shifted to differently structured systems and faunal response was global. The strengths of temporal ecological shifts, however, are mostly within the range of preextinction site-to-site variability, demonstrating that local ecological turnover was similar to geographic variation over a broad latitudinal range. In conjunction with varied site-specific temporal patterns of individual modes of life, these spatial and temporal heterogeneities argue against a concerted phase shift of molluscan assemblages from one well-defined regime to another. At a broader ecological level, by contrast, congruent tendencies emerge and suggest deterministic processes. These patterns comprise the well-known increase of deposit-feeding mollusks in postextinction assemblages and increases in predators and predator- resistant modes of life, i.e., those characterized by elevated mobility and infaunal life habits.