Data from: Constraints on the adult-offspring size relationship in protists

The relationship between adult and offspring size is an important aspect
of reproductive strategy. Although this filial relationship has been
extensively examined in plants and animals, we currently lack comparable
data for protists, whose strategies may differ due to the distinct
ecological and physiological constraints on single-celled organisms. Here,
we report measurements of adult and offspring sizes in 3,888 species and
subspecies of foraminifera, a class of large marine protists. Foraminifera
exhibit a wide range of reproductive strategies; species of similar adult
size may have offspring whose sizes vary 100-fold. Yet, a robust pattern
emerges. The minimum (5th percentile), median, and maximum (95th
percentile) offspring sizes exhibit a consistent pattern of increase with
adult size independent of environmental change and taxonomic variation
over the past 400 million years. The consistency of this pattern may arise
from evolutionary optimization of the offspring size-fecundity trade-off
and/or from cell-biological constraints that limit the range of
reproductive strategies available to single-celled organisms. When
compared with plants and animals, foraminifera extend the evidence that
offspring size covaries with adult size across an additional five orders
of magnitude in organism size.

成体与子代体型的关系是繁殖策略的重要研究维度。尽管这一亲子体型关联已在动植物类群中得到广泛探讨，但目前我们仍缺乏原生生物（protists）的可比数据——由于单细胞生物独特的生态与生理约束，原生生物的繁殖策略或存在显著差异。
本研究针对有孔虫（Foraminifera，一类大型海洋原生生物）的3888个物种及亚种，测定了其成体与子代的体型数据。有孔虫展现出多样的繁殖策略：即便成体体型相近，其子代体型的差异也可达100倍之多。
然而，研究揭示出一项稳健的普遍规律：在过去4亿年的时间尺度中，子代体型的最小值（5分位数）、中位数与最大值（95分位数）均随成体体型同步增长，且这一模式不受环境变化与类群差异的影响。
该规律的一致性，可能源于子代体型与繁殖力之间权衡关系的进化优化，或是单细胞生物所受的细胞生物学约束限制了其可采用的繁殖策略范围。
相较于动植物类群，有孔虫的研究数据将“子代体型随成体体型协同变化”的实证范围拓展了五个数量级的生物体尺寸区间。