Veylit Lara, Sæther Bernt-Erik, Gaillard Jean-Michel, Baubet Eric, Gamelon Marlène
Department of Biology Centre for Biodiversity Dynamics Norwegian University of Science and Technology Trondheim Norway.
Université Claude Bernard Lyon 1 Villeurbanne Cedex France.
Ecol Evol. 2021 Oct 1;11(21):14789-14804. doi: 10.1002/ece3.8164. eCollection 2021 Nov.
Despite their importance in shaping life history tactics and population dynamics, individual growth trajectories have only been rarely explored in the wild because their analysis requires multiple measurements of individuals throughout their lifetime and some knowledge of age, a key timer of body growth. The availability of long-term longitudinal studies of two wild boar populations subjected to contrasting environments (rich vs. poor) provided an opportunity to analyze individual growth trajectories. We quantified wild boar growth trajectories at both the population and the individual levels using standard growth models (i.e., Gompertz, logistic, and monomolecular models) that encompass the expected range of growth shapes in determinate growers. Wild boar is a rather altricial species, with a polygynous mating system and is strongly sexually dimorphic in size. According to current theories of life history evolution, we thus expect wild boar to display a sex-specific Gompertz type growth trajectory and lower sexual size dimorphism in the poorer environment. While wild boar displayed the expected Gompertz type trajectory in the rich site at the population level, we found some evidence for potential differences in growth shapes between populations and individuals. Asymptotic body mass, growth rate and timing of maximum growth rate differed as well, which indicates a high flexibility of growth in wild boar. We also found a cohort effect on asymptotic body mass, which suggests that environmental conditions early in life shape body mass at adulthood in this species. Our findings demonstrate that body growth trajectories in wild boar are highly diverse in relation to differences of environmental context, sex and year of birth. Whether the intermediate ranking of wild boar along the precocial-altricial continuum of development at birth may explain the ability of this species to exhibit this high diversity of growth patterns remains to be investigated.
尽管个体生长轨迹在塑造生活史策略和种群动态方面具有重要意义，但在野外却很少被研究，因为对其进行分析需要在个体的整个生命周期内进行多次测量，并且需要一些关于年龄的知识，而年龄是身体生长的关键计时器。对两个处于不同环境（丰富与贫瘠）的野猪种群进行长期纵向研究，为分析个体生长轨迹提供了机会。我们使用标准生长模型（即冈珀茨模型、逻辑斯蒂模型和单分子模型）在种群和个体层面量化了野猪的生长轨迹，这些模型涵盖了确定性生长者预期的生长形态范围。野猪是一种相当晚成的物种，具有一夫多妻的交配系统，并且在体型上存在强烈的两性异形。根据当前的生活史进化理论，因此我们预计野猪在较贫瘠的环境中会表现出特定性别的冈珀茨型生长轨迹，并且两性体型差异较小。虽然野猪在丰富环境的种群层面表现出预期的冈珀茨型轨迹，但我们发现了一些证据表明种群和个体之间在生长形态上可能存在差异。渐近体重、生长速率和最大生长速率的时间也有所不同，这表明野猪的生长具有高度的灵活性。我们还发现了一个对渐近体重的队列效应，这表明生命早期的环境条件塑造了该物种成年后的体重。我们的研究结果表明，野猪的身体生长轨迹因环境背景、性别和出生年份的差异而高度多样。野猪在出生时沿着早熟 - 晚成连续发育谱的中间排名是否可以解释该物种展现这种高度多样生长模式的能力，仍有待研究。
