Jops Kenneth, Dalling James W, O'Dwyer James P
Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801.
Smithsonian Tropical Research Institute, Balboa, Panama.
Proc Natl Acad Sci U S A. 2025 Jan 28;122(4):e2422348122. doi: 10.1073/pnas.2422348122. Epub 2025 Jan 24.
The question of what mechanisms maintain tropical biodiversity is a critical frontier in ecology, intensified by the heightened risk of biodiversity loss faced in tropical regions. Ecological theory has shed light on multiple mechanisms that could lead to the high levels of biodiversity in tropical forests. But variation in species abundances over time may be just as important as overall biodiversity, with a more immediate connection to the risk of extirpation and biodiversity loss. Despite the urgency, our understanding of the primary mechanisms driving fluctuations in species abundances has not been clearly established. Here, we introduce a theoretical framework based around life history; the schedule of birth, growth, and mortality over a lifespan, and its systematic variation across species. We develop a mean field model to predict expected fluctuations in abundance for a focal species in a larger community, and we quantify empirical life history variation among 90 tropical forest species in a 50 ha plot in Panama. Putting theory and data together, we show that life history provides a critical piece of this puzzle, allowing us to explain patterns of abundance fluctuations more accurately than previous models incorporating demographic stochasticity without life history variation, and without introducing unobserved couplings between species and their environment. This framework provides a starting point for more general models that incorporate multiple factors in addition to life history variation, and suggests the potential for a fine-grained assessment of extirpation risk based on the impacts of anthropogenic change on demographic rates across life stages.
何种机制维持热带生物多样性这一问题是生态学中的一个关键前沿领域，热带地区面临的生物多样性丧失风险加剧，使得这一问题更为突出。生态理论已阐明了多种可能导致热带森林生物多样性水平较高的机制。但是物种丰度随时间的变化可能与整体生物多样性同样重要，且与物种灭绝风险和生物多样性丧失有着更直接的联系。尽管情况紧急，但我们对驱动物种丰度波动的主要机制仍未明确了解。在此，我们引入一个基于生活史的理论框架；生活史是指一个生物体在其寿命期间出生、生长和死亡的时间表，以及其在物种间的系统变化。我们开发了一个平均场模型来预测较大群落中一个焦点物种的预期丰度波动，并对巴拿马一个50公顷地块内90种热带森林物种的经验生活史变化进行了量化。将理论与数据相结合，我们表明生活史为这个谜题提供了关键线索，使我们能够比以往未纳入生活史变化的人口统计学随机性模型更准确地解释丰度波动模式，且无需引入物种与其环境之间未观察到的耦合关系。这个框架为更通用的模型提供了一个起点，这些模型除了生活史变化外还纳入了多个因素，并基于人为变化对生命各阶段人口统计学速率的影响，为物种灭绝风险的精细评估提供了可能性。
