Data from: Taxonomic structure of the fossil record is shaped by sampling bias

Understanding biases that affect how species are partitioned into higher taxa is critical for much of palaeobiology, as higher taxa are commonly used to estimate species diversity through time. Using the deep-sea record of coccolithophorid microfossils over the last 150 million years (myr), we demonstrate that sampling and taxonomic effort are important drivers of the species/genus ratio. An unexpected two-stepped change in the ratio of species to genera over the last 150 myr correlates strongly with changes in both the number of deep-sea sites yielding coccolithophorids that have been studied and with the number of taxonomists who have published on those sections. While some limited biological signature from major extinction events can be recognized from changes in the species/genus ratio, the numbers of sites and the numbers of taxonomists combined explain some 82% of the observed variation over long periods of geological time. Such a strong correlation argues against using raw species/genus ratios to infer biological processes without taking sampling into account, and suggests that higher taxa cannot be taken as unbiased proxies for species diversity.

厘清影响物种被划归为高阶分类群（higher taxa）的各类偏倚，对古生物学的多数研究方向而言至关重要——因为高阶分类群常被用于估算地质历史时期的物种多样性。本研究基于过去1.5亿年间的颗石藻（coccolithophorid）微化石深海记录，证实采样强度与分类学研究投入是影响物属比（species/genus ratio）的关键驱动因素。在过去1.5亿年中，物属比出现了意料之外的两步式变化，该变化与两个因素的改变显著相关：一是已开展研究的产出颗石藻微化石的深海站位数量，二是针对这些地层剖面发表过相关研究的分类学家数量。尽管通过物属比的变化可识别出少量由重大灭绝事件带来的生物学信号，但站位数量与分类学家数量的综合因素，能够解释地质历史长期尺度下约82%的观测变异。这种极强的相关性表明，若未考量采样效应，直接使用原始物属比推断生物学过程的做法并不可靠；同时也说明，高阶分类群不能作为物种多样性的无偏替代指标（proxy）。