Abstract:
Species diversity increases with the temporal grain of samples according to the species-time relationship (STR), impacting palaeoecological analyses because the temporal grain (time averaging) of fossil assemblages varies by several orders of magnitude. We predict a positive relation between total abundance and sample size-independent diversity (ADR) in fossil assemblages because an increase in time averaging, determined by a decreasing sediment accumulation, should increase abundance and depress species dominance. We demonstrate that, in contrast to negative ADR of non-averaged living assemblages, the ADR of Holocene fossil assemblages is positive, unconditionally or when conditioned on the energy availability gradient. However, the positive fossil ADR disappears when conditioned on sediment accumulation, demonstrating that ADR is a signature of diversity scaling induced by variable time averaging. Conditioning ADR on sediment accumulation can identify and remove the scaling effect caused by time averaging, providing an avenue for unbiased biodiversity comparisons across space and time.
摘要:
根据物种-时间关系(STR),物种多样性随着样本的时间粒度而增加,影响古生态分析,因为化石组合的时间粒度(时间平均)变化了几个数量级。我们预测化石组合中的总丰度与样本量无关的多样性(ADR)之间存在正相关关系,因为时间平均的增加,由沉积物积累的减少决定,应该增加丰度并抑制物种优势。我们证明,与非平均生活组合的负面ADR相反,全新世化石组合的ADR是积极的,无条件地或以能量可用性梯度为条件时。然而,当受到沉积物积累的影响时,积极的化石ADR消失了,证明ADR是可变时间平均引起的多样性缩放的标志。调节沉积物堆积的ADR可以识别和消除时间平均引起的结垢效应,为跨空间和时间的无偏见的生物多样性比较提供了途径。