Spatial variation in the relationship between performance and metabolic rate in wild juvenile Atlantic salmon.
Maintenance of metabolic rate (MR, the energy cost of self-maintenance) is linked to behavioural traits and fitness and varies substantially within populations. Despite having received much attention, the causes and consequences of this variation remain obscure. Theoretically, such within-population variation in fitness-related traits can be maintained by environmental heterogeneity in selection patterns, but for MR, this has rarely been tested in nature. Here, we experimentally test whether the relationship between MR and performance can vary spatially by assessing survival, growth rate and movement of Atlantic salmon (Salmo salar L.) juveniles from 10 family groups differing in MR (measured as egg metabolism) that were stocked in parallel across 10 tributaries of a single watershed. The relationship between MR and relative survival and growth rate varied significantly among tributaries. Specifically, the effect of MR ranged from negative to positive for relative survival, whereas it was negative for growth rate. The association between MR and movement was positive and did not vary significantly among tributaries. These results are consistent with a fitness cost of traits associated with behavioural dominance that varies across relatively small spatial scales (within a single watershed). More generally, our results support the hypothesis that spatial heterogeneity in environmental conditions contributes to maintain within-population variation in fitness-related traits, such as MR.
Department of Biology, Centre for Biodiversity Dynamics, Norwegian University of Science and Technology, Realfagbygget, NO-7491, Trondheim, Norway.|Norwegian Institute for Nature Research, Høgskoleringen 9, NO-7034, Trondheim, Norway.
Grethe
G
Robertsen
Marine Scotland Science Freshwater Laboratory, Faskally, Pitlochry, Perthshire, PH16 5LB, UK.
John D
JD
Armstrong
USDA Forest Service Northern Research Station, 201 Holdsworth NRC, 160 Holdsworth Way, Amherst, MA, 01003, USA.
Keith H
KH
Nislow
Department of Biology, Centre for Biodiversity Dynamics, Norwegian University of Science and Technology, Realfagbygget, NO-7491, Trondheim, Norway.
Ivar
I
Herfindal
Cromarty Firth District Salmon Fisheries Board c/o CKD Galbraith, 17 Old Edinburgh Road, Inverness, IV2 3HF, UK.
Simon
S
McKelvey
Department of Biology, Centre for Biodiversity Dynamics, Norwegian University of Science and Technology, Realfagbygget, NO-7491, Trondheim, Norway.
Sigurd
S
Einum
D000818:Animals; D001481:Basal Metabolism; D005843:Geography; D008136:Longevity; D009068:Movement; D010063:Ovum / Q000502:physiology; D020317:Salmo salar / Q000254:growth & development / Q000502:physiology*; D012606:Scotland
dispersal; energetics; intraspecific variation; natural selection; standard metabolic rate