Data from: Cross-continental analysis shows that disturbance effects on reptile body condition do not predict abundance responses

Ecological disturbances are discrete events that alter or transform the
physical, chemical, or biological characteristics of ecosystems. Animal
populations are vulnerable to disturbance, and the risk-disturbance
hypothesis and population collapse framework propose that population
declines can be predicted by declines in animal body condition. However,
no research has empirically examined the general relationship between body
condition and abundance, nor their relationship in response to
disturbance. We used a combined dataset representing 33 studies and
>42,000 observations of 75 species from Australia, New Zealand,
Spain, and the United States to test predictions relating to the
relationship between reptile body condition and abundance. We first
investigated the relationship at the site level and then used
meta-analytical models to test whether populations showed linked changes
in abundance and body condition in response to disturbance. We further
tested whether key environmental and species traits influenced this
relationship and whether there was a time-lagged effect of body condition
responses on abundance. Our results provided no strong support for the
risk-disturbance hypothesis or population collapse framework. We found a
positive relationship between mean reptile body condition and abundance at
the site level. However, the relationship was largely lost when
investigating population responses to disturbance. We provide a new
conceptual framework that shows how disturbances can modify or uncouple
the relationship between abundance and body condition by influencing
underlying drivers, such as predation, competition, and resource
availability. As such, the impacts of disturbance on reptile body
condition cannot be assumed to reflect or predict abundance responses.
Monitoring programs that infer population impacts based on changes in body
condition should confirm the relationship between these two variables in
the relevant study system.

生态干扰（Ecological disturbances）是一类能够改变或重塑生态系统物理、化学与生物特征的离散事件。动物种群极易受到干扰影响，风险干扰假说（risk-disturbance hypothesis）与种群崩溃框架（population collapse framework）提出，可通过动物身体状况（body condition）的衰减预测种群数量的下降。然而，目前尚无研究从实证层面验证身体状况与种群丰度（abundance）间的普遍关联，也未探讨二者在响应干扰时的关联模式。

本研究整合了来自澳大利亚、新西兰、西班牙及美国的33项研究、共超42000条观测数据，涵盖75个爬行动物物种，以此检验与爬行动物体况和种群丰度间关联相关的预测假说。我们首先在样地尺度上探究二者的关联，随后采用元分析模型（meta-analytical models）检验种群的丰度与身体状况在响应干扰时是否存在同步变化。进一步地，我们还验证了关键环境因子与物种性状是否会影响这一关联，以及身体状况的响应是否会对种群丰度产生时滞效应（time-lagged effect）。

本研究结果并未为风险干扰假说或种群崩溃框架提供强有力的实证支持。我们在样地尺度上发现，爬行动物的平均身体状况与种群丰度呈正相关关系。但在探究种群对干扰的响应时，这一关联基本消失。

本研究提出了全新的概念框架，阐明了干扰可通过作用于捕食、种间竞争与资源可获得性等底层驱动因子，进而改变甚至解耦种群丰度与身体状况间的关联。因此，不能直接假设干扰对爬行动物体况的影响能够反映或预测其种群丰度的响应。基于身体状况变化推断种群影响的监测方案，应在对应的研究系统中验证这两个变量间的关联。