Arsovski Dragan, Tomović Ljiljana, Golubović Ana, Nikolić Sonja, Sterijovski Bogoljub, Ajtić Rastko, Ballouard Jean-Marie, Bonnet Xavier
CEBC, UMR-7372, CNRS ULR, 79360, Villiers en Bois, France.
Macedonian Ecological Society, Bulevar "Kuzman Josifovski-Pitu" 28/3-7, 1000, Skopje, Macedonia.
Oecologia. 2018 Apr;186(4):953-963. doi: 10.1007/s00442-018-4090-x. Epub 2018 Feb 26.
Juvenile growth strongly impacts life-history traits during adulthood. Yet, in juveniles with delayed maturity, elusiveness has hindered age-specific studies of growth, precluding any detailed research on its consequences later in life. Different complex growth patterns have been extracted from captive animals, suggesting species-specific trajectories occur in free-ranging animals. How pronounced are growth and body size variation (VBS) throughout a long-lived ectotherm's life? Is VBS constant among age classes prior to maturity, or do compensatory and/or cumulative effects driven by long-lived-animal-specific strategies create distinct VBS cohorts, to ensure survival? To tackle the issue, we modelled growth data from continuous and dense annual capture-mark-recapture sampling (5096 body measurements of 1134 free-ranging individuals) of both immature and mature, long-lived Hermann's tortoises. We analysed population, cohort, and individual-based growth and VBS. Growth ring inferred ages were cross validated with annual recaptures in 289 juveniles. Analyses unravelled an S-shaped growth curve and identified three age cohorts across which VBS increases in a step-wise manner. Neonate-specific constraints and compensatory effects seem to control VBS until 4 years of age, possibly promoting survival with size. Subsequently, a hardened carapace takes over and cumulative effects fuelled by faster growth progressively increase VBS. Whereas ungulates are in a hurry to attain adult size before growth ceases (minimizing VBS), indeterminately growing tortoises can shape individual asymptotic sizes even after growth decelerates. Tortoise size is clearly shaped by age-specific ecological constraints; interestingly, it is likely the carapace that conducts the strategy, rather than maturity per se.
幼年生长对成年后的生活史特征有强烈影响。然而，对于成熟延迟的幼体，其难以捉摸性阻碍了针对特定年龄的生长研究，使得无法对其成年后的影响进行任何详细研究。从圈养动物中提取了不同的复杂生长模式，这表明在自由放养的动物中存在物种特异性的生长轨迹。在一种长寿变温动物的一生中，生长和体型变化（VBS）有多显著？在成熟之前的不同年龄组中，VBS是否恒定，或者由长寿动物特定策略驱动的补偿和/或累积效应是否会产生不同的VBS队列，以确保生存？为了解决这个问题，我们对未成熟和成熟的长寿赫尔曼陆龟的连续且密集的年度标记重捕抽样（1134只自由放养个体的5096次体型测量）所获得的生长数据进行了建模。我们分析了种群、队列和基于个体的生长以及VBS。通过对289只幼龟的年度重捕对生长环推断的年龄进行了交叉验证。分析揭示了一条S形生长曲线，并确定了三个年龄队列，VBS在这三个队列中呈逐步增加的趋势。幼龟特有的限制和补偿效应似乎在4岁之前控制着VBS，这可能有助于体型较大的幼龟存活。随后，坚硬的背甲开始起作用，更快生长所带来的累积效应逐渐增加VBS。有蹄类动物在生长停止前急于达到成年体型（使VBS最小化），而生长不确定的陆龟即使在生长减速后仍能塑造个体的渐近体型。陆龟的体型显然受到特定年龄的生态限制的影响；有趣的是，执行这一策略的可能是背甲，而非成熟本身。
