The Refugial Squeeze: A Globally Relevant Mechanism of Species Decline Revealed by a Threatened Amphibian
- 1School of Environmental and Life Sciences The University of Newcastle Callaghan New South Wales Australia
- 2Centre for African Conservation Ecology Nelson Mandela University Port Elizabeth South Africa
Abstract
A key outcome of the Global Biodiversity Crisis is the contraction and range shift of species distribution into refugial habitats that afford protection against threatening processes. Range contractions driven by spatially overlapping threats may fragment populations to the point where functional habitat is lost. This study identifies a range contraction of the Vulnerable green and golden bell frog ( Ranoidea aurea ) in south‐east Australia using a multi‐method approach. We fitted alpha hulls, species distribution models (MaxEnt, Random Forest, Boosted Regression Trees and an AUC‐weighted ensemble model) and conducted a hypervolume analysis to quantify change in the species' range and niche between full (historical) and contemporary periods. Our findings suggest R. aurea has undergone niche contraction and displacement with a directional shift into coastal saline‐influenced refugia. Our results demonstrated a 76% reduction in extent of occurrence, a suitable habitat reduction of ~96%, and an environmental niche contraction of 57%. The remaining habitat was strongly associated with coastal proximity with shifts towards more saline environments. The concentration of R. aurea in coastal regions suggests intensified dependence on coastal refugia, persisting in salt‐exposed habitat that may suppress chytrid fungus. Yet, the threat abatement afforded by low‐lying, saline coastal environments is wedging R. aurea into chytrid refugia that is at risk from sea level rise. Refugial squeeze is a globally relevant phenomenon likely affecting a suite of coastal species that highlights the value of integrating geometric and probabilistic niche approaches with species distribution models to resolve temporal contraction in species distributions. Protection of refugial squeeze zones from sea level rise will ultimately determine the future range and population viability of coastal species.
Versions
Related
- Host and Environmental Factors Outweigh Pathogen in Shaping Skin Microbiome of a Threatened Andean Amphibian Community
- Growth and gonadal transcriptome changes in the largest extant amphibian after prolonged heat stress
- Overcoming Detection Lag in a Cryptic Panzootic: Chytrid Invasion Linked to Historically Enigmatic Amphibian Declines in the Brazilian Atlantic Forest
- Where to improve the European protected areas network to represent threatened fungi?
- Private forest reserves in Brazils agricultural landscapes effectively sustain the occupancy and abundance of multiple threatened large vertebrate
BibTeX
@article{tunstill2026refugial,
title = {{The Refugial Squeeze: A Globally Relevant Mechanism of Species Decline Revealed by a Threatened Amphibian}},
author = {Kate Tunstill and Matt W. Hayward and Hannah Power and Darren Southwell and John Gould and Will Farebrother and Michael Mahony and Alex Callen},
journal = {Ecology and evolution},
year = {2026},
month = oct,
doi = {10.1002/ece3.74417},
url = {https://europepmc.org/article/PMC/PMC13671101},
note = {CC BY},
}
RIS
TY - JOUR
TI - The Refugial Squeeze: A Globally Relevant Mechanism of Species Decline Revealed by a Threatened Amphibian
AU - Kate Tunstill
AU - Matt W. Hayward
AU - Hannah Power
AU - Darren Southwell
AU - John Gould
AU - Will Farebrother
AU - Michael Mahony
AU - Alex Callen
PY - 2026
DA - 2026/10/01
JO - Ecology and evolution
DO - 10.1002/ece3.74417
UR - https://europepmc.org/article/PMC/PMC13671101
AB - A key outcome of the Global Biodiversity Crisis is the contraction and range shift of species distribution into refugial habitats that afford protection against threatening processes. Range contractions driven by spatially overlapping threats may fragment populations to the point where functional habitat is lost. This study identifies a range contraction of the Vulnerable green and golden bell frog ( Ranoidea aurea ) in south‐east Australia using a multi‐method approach. We fitted alpha hulls, species distribution models (MaxEnt, Random Forest, Boosted Regression Trees and an AUC‐weighted ensemble model) and conducted a hypervolume analysis to quantify change in the species' range and niche between full (historical) and contemporary periods. Our findings suggest R. aurea has undergone niche contraction and displacement with a directional shift into coastal saline‐influenced refugia. Our results demonstrated a 76% reduction in extent of occurrence, a suitable habitat reduction of ~96%, and an environmental niche contraction of 57%. The remaining habitat was strongly associated with coastal proximity with shifts towards more saline environments. The concentration of R. aurea in coastal regions suggests intensified dependence on coastal refugia, persisting in salt‐exposed habitat that may suppress chytrid fungus. Yet, the threat abatement afforded by low‐lying, saline coastal environments is wedging R. aurea into chytrid refugia that is at risk from sea level rise. Refugial squeeze is a globally relevant phenomenon likely affecting a suite of coastal species that highlights the value of integrating geometric and probabilistic niche approaches with species distribution models to resolve temporal contraction in species distributions. Protection of refugial squeeze zones from sea level rise will ultimately determine the future range and population viability of coastal species.
SN - 2045-7758
ER -