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Compensatory recruitment unlikely in high-elevation amphibian populations challenged with disease

March 27, 2023
  1. Understanding the causes of population variation in host response to disease, and the mechanisms of persistence, can serve as vital information for species conservation. One such mechanism of population persistence that has gained support is the demographic process of compensatory recruitment. Host populations may persist by increasing recruitment to compensate for reduced survival due to infection, thus limiting the negative effects of the disease on population trajectories. However, high-elevation populations are inherently vulnerable to stochastic processes and may be limited in their ability to exhibit compensatory recruitment relative to lower elevation populations.
  2. We use long-term mark–recapture data from five populations of boreal toads Anaxyrus boreas boreas, across an elevational gradient in Colorado, before and after pathogen arrival to assess whether populations can persist with Batrachochytrium dendrobatidis (Bd) via compensatory recruitment.
  3. Prior to pathogen arrival, we found a life-history trade-off between survival and recruitment across elevations, where high-elevation toads have high survival but lower recruitment and vice versa at lower elevations.
  4. Pathogen arrival had a strong negative effect on apparent annual survival and recruitment leading to negative population growth rates and dramatically reduced host abundances. The data did not support the occurrence of compensatory recruitment.
  5. Synthesis and applications. Our unique dataset indicates that demographic responses to pathogens may be environmentally (i.e. elevationally) context dependent and highlights the value of long-term monitoring. We recommend that practitioners verify that potential persistence mechanisms occur across multiple populations and relevant environmental gradients to counter any assumptions of the mechanism existing species-wide. Quantifying variation in population responses to disease will aid in understanding the bounds of such persistence mechanisms and identify particularly vulnerable populations where mechanisms are nonexistent.
Publication Year 2023
Title Compensatory recruitment unlikely in high-elevation amphibian populations challenged with disease
DOI 10.1111/1365-2664.14310
Authors Bennett Hardy, Erin L. Muths, Bradley Lambert, Scott C. Schneider, W. C. Funk, Larissa L. Bailey
Publication Type Article
Publication Subtype Journal Article
Series Title Journal of Applied Ecology
Index ID 70241785
Record Source USGS Publications Warehouse
USGS Organization Fort Collins Science Center