Distinguishing between determinate and indeterminate growth in a long-lived mammal

Background: The growth strategy of a species influences many key aspects of its life-history. Animals can either grow indeterminately (throughout life), or grow determinately, ceasing at maturity. In mammals, continued weight gain after maturity is clearly distinguishable from continued skeletal growth (indeterminate growth). Elephants represent an interesting candidate for studying growth because of their large size, long life and sexual dimorphism. Objective measures of their weight, height and age, however, are rare. Results: We investigate evidence for indeterminate growth in the Asian elephant Elephas maximus using a longitudinal dataset from a semi-captive population. We fit growth curves to weight and height measurements, assess sex differences in growth, and test for indeterminate growth by comparing the asymptotes for height and weight curves. Our results show no evidence for indeterminate growth in the Asian elephant; neither sex increases in height throughout life, with the m...

研究背景：物种的生长策略会对其生活史的诸多关键方面产生显著影响。动物的生长模式可分为无限生长（indeterminate growth，即终生持续生长）与有限生长（determinate growth，即成熟后停止生长）两类。在哺乳动物中，成熟后持续的体重增加与持续的骨骼生长（即无限生长）有着明确的区分界限。大象凭借其庞大体型、超长寿命以及显著的性二态性（sexual dimorphism），成为探究生长模式的理想研究对象。然而，目前关于其体重、体高与年龄的客观实测数据却较为稀缺。研究结果：我们借助来自半圈养种群（semi-captive population）的纵向数据集（longitudinal dataset），探究了亚洲象（Elephas maximus）存在无限生长的相关证据。我们将生长曲线（growth curves）拟合至体重与体高的实测数据，评估了不同性别的生长差异，并通过比较体高与体重生长曲线的渐近线（asymptotes），检验了无限生长假说。本研究结果未发现亚洲象存在无限生长的证据：两个性别的体高均未随终生持续增高，且的 m...