Institut Català de Paleontologia Miquel Crusafont, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Barcelona, Spain.
Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain.
Sci Rep. 2021 Nov 24;11(1):22862. doi: 10.1038/s41598-021-02192-4.
The 1-m-tall dwarf elephant Palaeoloxodon falconeri from the Pleistocene of Sicily (Italy) is an extreme example of insular dwarfism and epitomizes the Island Rule. Based on scaling of life-history (LH) traits with body mass, P. falconeri is widely considered to be 'r-selected' by truncation of the growth period, associated with an early onset of reproduction and an abbreviated lifespan. These conjectures are, however, at odds with predictions from LH models for adaptive shifts in body size on islands. To settle the LH strategy of P. falconeri, we used bone, molar, and tusk histology to infer growth rates, age at first reproduction, and longevity. Our results from all approaches are congruent and provide evidence that the insular dwarf elephant grew at very slow rates over an extended period; attained maturity at the age of 15 years; and had a minimum lifespan of 68 years. This surpasses not only the values predicted from body mass but even those of both its giant sister taxon (P. antiquus) and its large mainland cousin (L. africana). The suite of LH traits of P. falconeri is consistent with the LH data hitherto inferred for other dwarfed insular mammals. P. falconeri, thus, not only epitomizes the Island Rule but it can also be viewed as a paradigm of evolutionary change towards a slow LH that accompanies the process of dwarfing in insular mammals.
来自西西里岛（意大利）更新世的 1 米高的矮象 Palaeoloxodon falconeri 是岛屿侏儒化的极端例子，也是岛屿法则的缩影。根据体型与生命史（LH）特征的比例关系，P. falconeri 被广泛认为通过缩短生长期而成为“r 选择者”，这与生殖期的提前开始和寿命缩短有关。然而，这些推测与岛屿上体型适应性变化的 LH 模型的预测不一致。为了确定 P. falconeri 的 LH 策略，我们使用骨骼、臼齿和獠牙组织学来推断生长速度、首次繁殖年龄和寿命。我们从所有方法得到的结果都是一致的，这表明这种岛屿矮象的生长速度非常缓慢，持续时间长；在 15 岁时达到成熟；最小寿命为 68 年。这不仅超过了根据体重预测的值，甚至超过了其巨型姐妹分类群（P. antiquus）和大型大陆表亲（L. africana）的值。P. falconeri 的 LH 特征与迄今为止为其他矮化岛屿哺乳动物推断的 LH 数据一致。因此，P. falconeri 不仅是岛屿法则的缩影，而且可以被视为岛屿哺乳动物侏儒化过程中伴随的慢 LH 进化变化的范例。
