Stage-Specific Demographic Effects of Hydrologic Variation in a Stream Salamander

Area of Science:

• Ecology
• Evolutionary Biology
• Climate Change Biology

Background:

• Organisms with complex life histories may respond differently to climate variations.
• Stream-associated species often have multistage life histories, influencing demographic consequences of floods and droughts.
• High-resolution, long-term data are needed to track stage-specific demographic responses, but are rarely available.

Purpose of the Study:

• To quantify the effects of flooding and drying magnitude on stage-specific vital rates and population growth in the headwater stream salamander *Gyrinophilus porphyriticus*.
• To understand how complex life cycles influence demographic resilience to climate variation.

Main Methods:

• Utilized 8 years of capture-recapture data for *Gyrinophilus porphyriticus*.
• Quantified stage-specific vital rates (recruitment, survival, metamorphosis) and population growth rates (λ).
• Assessed the impact of flooding and drying magnitude on these demographic parameters.

Main Results:

• Drying reduced larval recruitment but increased metamorphosis (adult recruitment).
• Flooding reduced adult recruitment but did not affect larval recruitment.
• Larval and adult survival declined with flooding; both stages were unaffected by drying.
• Annual population growth rates (λ) declined with both flooding and drying, and showed a decreasing trend over the study period (2012-2021).

Conclusions:

• *Gyrinophilus porphyriticus* populations exhibit resilience to hydrologic variation due to compensatory effects between larval and adult recruitment.
• Complex life cycles can facilitate resilience to climate variation by allowing compensatory demographic responses across different life stages.
• Increasingly frequent and intense hydrologic variation poses a threat to population growth, even with demographic compensation mechanisms.