Patterns of niche contraction identify vital refuge areas for declining mammals

Aim Investigation of realized niche contraction in declining species can help us understand how and where threats are being either mediated or tolerated across landscapes. It also provides insights into species' sensitivity to environmental change that are unable to be identified through analys...

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Bibliographic Details
Published in:Diversity & distributions 2020-11, Vol.26 (11), p.1467-1482
Main Authors: von Takach, Brenton, Scheele, Ben C., Moore, Harry, Murphy, Brett P., Banks, Sam C.
Format: Article
Language:English
Subjects:
Algorithms
BIODIVERSITY RESEARCH
Contraction
Datasets
ecological niche model
Ecological niches
Endangered & extinct species
Environmental changes
Environmental conditions
extent of occurrence
Genetic diversity
Geographical distribution
Historical account
Hypotheses
Land degradation
mammal
Niche breadth
niche hypervolume
niche reduction hypothesis
Nonnative species
Population decline
range contraction
Reduction
refuge
Resilience
Species
species decline
threatening process
Threats
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Summary:Aim Investigation of realized niche contraction in declining species can help us understand how and where threats are being either mediated or tolerated across landscapes. It also provides insights into species' sensitivity to environmental change that are unable to be identified through analysis of declines in range size or abundance alone. Here, we apply the recently proposed "niche reduction hypothesis" to investigate relationships between trends in niche breadth and geographic distribution of declining species. Location Northern Australia. Methods We compare and contrast contemporary and historical data sets to examine the relationship between extent of occurrence (EOO) and realized niche hypervolume, and investigate changes in species' utilization of environmental space through time via generalized linear modelling and bootstrapping of historical values. We also use the "Maxent" algorithm to create and stack contemporary and historical ecological niche models (ENMs) and identify regions where resilience to threatening processes is maximized. Results We found larger mean reductions in niche hypervolume (39%) than EOO (30.5%), with little correlation (r = 0.07) between the two measures, suggesting that contraction of realized niche breadth can be largely independent of reduction in EOO. We also identified a general set of environmental conditions towards which species' realized niches contracted. Comparison of stacked ENMs allowed us to identify regions of natural refuge where environmental conditions are associated with increased species resilience to threats, and conversely, regions where habitat suitability has declined. Main conclusions Examining species declines from an ecological niche perspective provides a powerful tool for understanding how environmental conditions, biotic interactions and species traits shape responses to local and global environmental changes. Quantifying reductions in niche breadth is crucial as contraction to a narrower subset of environmental space can reduce a species' ability to tolerate other threats and potentially lower adaptive capacity and genetic diversity, increasing extinction risk.
ISSN:1366-9516
1472-4642
DOI:10.1111/ddi.13145