Source-sink dynamics within a complex life history

Area of Science:

• Ecology
• Population Dynamics
• Conservation Biology

Background:

• Source-sink dynamics are crucial for population stability, especially in species with complex life histories.
• Understanding stage-specific movement and survival is key to deciphering these dynamics in structured populations.
• Headwater stream ecosystems with distinct geomorphic patches (riffles and pools) provide a model system for studying these processes.

Purpose of the Study:

• To investigate source-sink patch dynamics in the stream salamander Gyrinophilus porphyriticus.
• To test the hypothesis that riffles and pools function as source and sink habitats for this species.
• To determine the demographic effects of stage-specific (larval and adult) movement and survival.

Main Methods:

• Utilized 8 years of capture-recapture data from 4491 Gyrinophilus porphyriticus individuals.
• Estimated stage-specific survival and movement probabilities between riffles and pools.
• Developed a stage-structured, two-patch model to simulate population dynamics.

Main Results:

• Monthly survival was higher for both larvae and adults in pools compared to riffles.
• Larvae preferentially moved from riffles to pools, while adults moved from pools to riffles.
• Simulations showed riffles are sinks dependent on adult and larval immigration; larval movement stabilized both patches, while adult movement alone destabilized pools.

Conclusions:

• Larval movement is critical for stabilizing sink habitats (riffles) and offsetting destabilizing adult movement.
• Complex life histories with stage-specific vital rates and movement significantly influence source-sink dynamics.
• These findings advance the understanding of spatial ecology and population persistence in structured populations.