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Modeling the Size Spectrum for Macroinvertebrates and Fishes in Stream Ecosystems
Published on: July 30, 2019
Coexistence in streams: do source-sink dynamics allow salamanders to persist with fish predators?
Adam J Sepulveda1, Winsor H Lowe
1Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA. asepulveda@usgs.gov
Oecologia
|February 25, 2011
Summary
Source-sink dynamics do not explain how stream fish and salamanders coexist. Local factors, not dispersal, are key to their survival, highlighting the importance of empirical data in ecological studies.
Area of Science:
- Ecology
- Evolutionary Biology
- Conservation Biology
Background:
- Intraguild predation, where predators and prey also prey on each other, can be stabilized by source-sink dynamics.
- Empirical evidence for source-sink dynamics facilitating coexistence between intraguild predators and prey is scarce.
- Stream fish and Torrent salamanders (Dicamptodon aterrimus) form an intraguild predator-prey relationship.
Purpose of the Study:
- To investigate if source-sink dynamics promote coexistence between stream fishes and Torrent salamanders.
- To differentiate between local-scale mechanisms and spatial dynamics in maintaining species coexistence.
Main Methods:
- Capture-mark-recapture techniques to estimate population parameters.
- Genetic analyses to assess gene flow and population structure.
- Stable isotope analysis to infer dietary relationships and trophic interactions.
- Comparison of population dynamics (survival, recruitment, growth) between upstream (fishless) and downstream (fish-present) reaches.
Main Results:
- Downstream reaches with fish were not population sinks for salamanders, despite fish consuming salamander larvae.
- No significant differences were observed in apparent survival, recruitment, or population growth rates between upstream and downstream reaches.
- Net emigration did not differ between reaches, and frequent salamander movement was attributed to seasonal habitat shifts rather than intraguild predation.
Conclusions:
- Local-scale mechanisms, rather than dispersal dynamics driven by source-sink processes, are more critical for the coexistence of stream salamanders and fish.
- Empirical data on dispersal and gene flow are crucial for distinguishing between local and spatial coexistence mechanisms in ecological communities.
- This study underscores the complexity of predator-prey dynamics in stream ecosystems and the need for nuanced investigations beyond simple source-sink models.
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