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Coexistence in streams: Do source-sink dynamics allow salamanders to persist with fish predators?

January 1, 2011

Theory suggests that source–sink dynamics can allow coexistence of intraguild predators and prey, but empirical evidence for this coexistence mechanism is limited. We used capture–mark–recapture, genetic methods, and stable isotopes to test whether source–sink dynamics promote coexistence between stream fishes, the intraguild predator, and stream salamanders (Dicamptodon aterrimus), the intraguild prey. Salamander populations from upstream reaches without fish were predicted to maintain or supplement sink populations in downstream reaches with fish. We found instead that downstream reaches with fish were not sinks even though fish consumed salamander larvae—apparent survival, recruitment, and population growth rate did not differ between upstream and downstream reaches. There was also no difference between upstream and downstream reaches in net emigration. We did find that D. aterrimus moved frequently along streams, but believe that this is a response to seasonal habitat changes rather than intraguild predation. Our study provides empirical evidence that local-scale mechanisms are more important than dispersal dynamics to coexistence of streams salamanders and fish. More broadly, it shows the value of empirical data on dispersal and gene flow for distinguishing between local and spatial mechanisms of coexistence.

Citation Information

Publication Year 2011
Title Coexistence in streams: Do source-sink dynamics allow salamanders to persist with fish predators?
DOI 10.1007/s00442-011-1935-y
Authors Adam J. Sepulveda, W.H. Lowe
Publication Type Article
Publication Subtype Journal Article
Series Title Oecologia
Series Number
Index ID 70035728
Record Source USGS Publications Warehouse
USGS Organization Northern Rocky Mountain Science Center