Understanding metrics of stress in the context of invasion history: the case of the brown treesnake

Invasive species can exert rapid depletion of resources after introduction and, in turn, affect their own population density. Additionally, management actions can have direct and indirect effects on demography. Physiological variables can predict demographic change but are often restrictedtosnapshot...

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Bibliographic Details
Published in:Conservation Physiology 2021, Vol.9 (1), p.1
Main Authors: Claunch, Natalie, Moore, Ignacio, Waye, Heather, Schoenle, Laura, Oakey, Samantha J, Reed, Robert N, Romagosa, Christina
Format: Report
Language:English
Subjects:
Animal introduction
Environmental aspects
Physiological aspects
Stress (Physiology)
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Summary:Invasive species can exert rapid depletion of resources after introduction and, in turn, affect their own population density. Additionally, management actions can have direct and indirect effects on demography. Physiological variables can predict demographic change but are often restrictedtosnapshots-in-time and delayed confirmation of changes in population density reduces theirutility. To evaluate the relationships between physiologyanddemography, weassessed metrics of individualand demographic stress (baseline and 1-h corticosterone (CORT), body condition and bacterial killing ability) in the invasive snake Boiga irregularis on Guam collected in intervals of 10-15 years. We also assessed potential discrepancies between different methods of measuring hormones [radioimmunoassay (RIA) versus enzyme immunoassay (EIA)]. The magnitude of difference between RIA and EIA was negligible and did not change gross interpretation of our results. We found that body condition was higher in recent samples (2003 and 2018) versus older (1992-93) samples. We found corresponding differences in baseline CORT, with higher baseline CORT in older, poorer body condition samples. Hormonal response to acute stress was higher in 2018 relative to 2003. We also found a weak relationship between circulating CORT and bacterial killing ability among 2018 samples, but the biological significance of the relationship is not clear. In an effort to develop hypotheses for future investigation of the links between physiology and demography in this and other systems, we discuss how the changes in CORT and body condition may reffect changes in population dynamics, resource availability or management pressure. Ultimately, we advocate for the synchronization of physiology and management studies to advance the field of applied conservation physiology.
ISSN:2051-1434
2051-1434
DOI:10.1093/conphys/coab008