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. Disturbance can cause animal populations to decline and, according to the risk-disturbance hypothesis and population collapse framework, these 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 of America 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. 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. As such, our results provided no support for the risk-disturbance hypothesis and limited support for the population collapse framework. Therefore, the impacts of disturbance on reptile body condition cannot be assumed to reflect or predict abundance responses. 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. Monitoring programs that infer population impacts based on changes in body condition should first confirm the relationship between these two variables in the relevant study system.

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Journal
Global Change Biology
Published
2025-07-01
DOI
https://doi.org/10.1111/gcb.70295
Citations
1
Primary Topic
Species Distribution and Climate Change
Type
article
Field-Weighted Citation Impact
1.84

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article

Cross‐Continental Analysis Shows That Disturbance Effects on Reptile Body Condition Do Not Predict Abundance Responses

Tim S. Doherty, Lee A. Fitzgerald, Christopher Woolley, Annabel L. Smith et al.
1 citations
Global Change Biology
Species Distribution and Climate Change
1.84
article

Cross‐Continental Analysis Shows That Disturbance Effects on Reptile Body Condition Do Not Predict Abundance Responses

Tim S. Doherty, Lee A. Fitzgerald, Christopher Woolley, Annabel L. Smith, Jade E. Keehn, Adrian F. Wayne, Juli G. Pausas, Graham G. Thompson, Rickard Abom, Chris R. Feldman, Tim S. Jessop, Calum Irvine, Kristina J. Macdonald, Robert A. Davis, Steven J. Hromada, Don A. Driscoll, Xavier Santos, Shannon J. Dundas, Stacey L. Weiss, Brent D. Johnson, Danielle Stokeld, Danielle K. Walkup, Chris R. Dickman, Patricia A. Fleming, Michael Craig, Scott A. Thompson, C. M. Gienger, Josabel Belliure, Daniel J. Leavitt, Daniel F. Bohórquez Fandiño, Dylan M. Westaway, Gordon R. Friend, Sabrina E. Duncan
article en
1 citations

Abstract

Ecological disturbances are discrete events that alter or transform the physical, chemical, or biological characteristics of ecosystems. Disturbance can cause animal populations to decline and, according to the risk-disturbance hypothesis and population collapse framework, these 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 of America 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. 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. As such, our results provided no support for the risk-disturbance hypothesis and limited support for the population collapse framework. Therefore, the impacts of disturbance on reptile body condition cannot be assumed to reflect or predict abundance responses. 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. Monitoring programs that infer population impacts based on changes in body condition should first confirm the relationship between these two variables in the relevant study system.

Global Change BiologyVol. 31(7)
Edith Cowan University (AU), The University of Sydney (AU), Oregon Department of Fish and Wildlife (US), NSW Department of Planning and Environment (AU), University of Nevada, Reno (US), United States Fish and Wildlife Service (US), University of Puget Sound (US), Deakin University (AU), Charles Sturt University (AU), The University of Queensland (AU), Murdoch University (AU), The University of Western Australia (AU), Universidade do Porto (PT), Austin Peay State University (US), Universidad de Alcalá (ES), Curtin University (AU), Government of Western Australia (AU), New South Wales Department of Primary Industries (AU), Charles Darwin University (AU), Victoria University of Wellington (NZ), Hochschule Bremerhaven (DE), Centre d'Investigacions sobre Desertificació (ES), Terrestrial Ecosystem Research Network (AU), California State University, Fresno (US), James Cook University (AU), Texas A&M University (US)
M.J. Murdock Charitable Trust, Holsworth Wildlife Research Endowment, Parks Victoria, Edith Cowan University, Charles Darwin University, Minerals Research Institute of Western Australia, Threatened Species Recovery Hub, Australian Research Council
Openalex Percentile: Top 14%
Species Distribution and Climate Change
1.84
DOIOpen Access PDFOpenAlex
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