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We lack a strong understanding of how organisms with complex life histories respond to climate variation. Many stream-associated species have multi-stage life histories that are likely to influence the demographic consequences of floods and droughts. However, tracking stage specific demographic responses requires high-resolution, long-term data that are rare. We used eight years of capture-recapture data for the headwater stream salamander Gyrinophilus porphyriticus to quantify the effects of flooding and drying magnitude on stage-specific vital rates and population growth. Drying reduced larval recruitment but increased the probability of metamorphosis (i.e., adult recruitment). Flooding reduced adult recruitment but had no effect on larval recruitment. Larval and adult survival declined with flooding but were unaffected by drying. Annual population growth rates (lambda, ) declined with flooding and drying. Lambda also declined over the study period (2012 – 2021), although mean was 1.0 over this period. Our results indicate that G. porphyriticus populations are resilient to hydrologic variation due to compensatory effects on recruitment of larvae vs. adults (i.e., reproduction vs. metamorphosis). Complex life cycles may enable this resilience to climate variation by creating opportunities for compensatory demographic responses across stages. However, more frequent and intense hydrologic variation in the latter half of this study contributed to a decline in over time, suggesting that increasing environmental variability poses a threat even when demographic compensation occurs.
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Pathways to global-change effects on biodiversity: new opportunities for dynamically forecasting demography and species interactions
In structured populations, persistence under environmental change may be particularly threatened when abiotic factors simultaneously negatively affect survival and reproduction of several life cycle stages, as opposed to a single stage. Such effects can then be exacerbated when species interactions generate reciprocal feedbacks between the demographic rates of the different species. Despite the importance of such demographic feedbacks, forecasts that account for them are limited as individual-based data on interacting species are perceived to be essential for such mechanistic forecasting—but are rarely available. Here, we first review the current shortcomings in assessing demographic feedbacks in population and community dynamics. We then present an overview of advances in statistical tools that provide an opportunity to leverage population-level data on abundances of multiple species to infer stage-specific demography. Lastly, we showcase a state-of-the-art Bayesian method to infer and project stage-specific survival and reproduction for several interacting species in a Mediterranean shrub community. This case study shows that climate change threatens populations most strongly by changing the interaction effects of conspecific and heterospecific neighbours on both juvenile and adult survival. Thus, the repurposing of multi-species abundance data for mechanistic forecasting can substantially improve our understanding of emerging threats on biodiversity.
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- Award ID(s):
- 2247042
- PAR ID:
- 10411163
- Date Published:
- Journal Name:
- Proceedings of the Royal Society B: Biological Sciences
- Volume:
- 290
- Issue:
- 1993
- ISSN:
- 0962-8452
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1098/rspb.2022.1494
