21466553
not annotated - annotated - LINNAEUS only
Adaptive trade-offs in juvenile salmonid metabolism associated with habitat partitioning between coho salmon and steelhead trout in coastal streams.
1. Adaptive trade-offs are fundamental to the evolution of diversity and the coexistence of similar taxa and occur when complimentary combinations of traits maximize efficiency of resource exploitation or survival at different points on environmental gradients. 2. Standard metabolic rate (SMR) is a key physiological trait that reflects adaptations to baseline metabolic performance, whereas active metabolism reflects adaptations to variable metabolic output associated with performance related to foraging, predator avoidance, aggressive interactions or migratory movements. Benefits of high SMR and active metabolism may change along a resource (productivity) gradient, indicating that a trade-off exists among active metabolism, resting metabolism and energy intake. 3. We measured and compared SMR, maximal metabolic rate (MMR), aerobic scope (AS), swim performance (UCrit) and growth of juvenile hatchery and wild steelhead and coho salmon held on high- and low-food rations in order to better understand the potential significance of variation in SMR to growth, differentiation between species, and patterns of habitat use along a productivity gradient. 4. We found that differences in SMR, MMR, AS, swim performance and growth rate between steelhead trout and coho salmon were reduced in hatchery-reared fish compared with wild fish. Wild steelhead had a higher MMR, AS, swim performance and growth rate than wild coho, but adaptations between species do not appear to involve differences in SMR or to trade-off increased growth rate against lower swim performance, as commonly observed for high-growth strains. Instead, we hypothesize that wild steelhead may be trading off higher growth rate for lower food consumption efficiency, similar to strategies adopted by anadromous vs. resident brook trout and Atlantic salmon vs. brook trout. This highlights potential differences in food consumption and digestion strategies as cryptic adaptations ecologically differentiating salmonid species. 5. We hypothesize that divergent digestive strategies, which are common and well documented among terrestrial vertebrates, may be an important but overlooked aspect of adaptive strategies of juvenile salmonids, and fish in general.
Ann file
T1 Species 97 108 coho salmon
N1 Reference T1 Taxonomy:8019
T2 Species 113 128 steelhead trout
N2 Reference T2 Taxonomy:8022
T3 Species 1072 1081 steelhead
N3 Reference T3 Taxonomy:8022
T4 Species 1086 1097 coho salmon
N4 Reference T4 Taxonomy:8019
T5 Species 1400 1415 steelhead trout
N5 Reference T5 Taxonomy:8022
T6 Species 1420 1431 coho salmon
N6 Reference T6 Taxonomy:8019
T7 Species 1499 1508 steelhead
N7 Reference T7 Taxonomy:8022
T8 Species 1574 1578 coho
N8 Reference T8 Taxonomy:8019
T9 Species 1806 1815 steelhead
N9 Reference T9 Taxonomy:8022
T10 Species 1950 1961 brook trout
N10 Reference T10 Taxonomy:8038
T11 Species 1966 1981 Atlantic salmon
N11 Reference T11 Taxonomy:8030
T12 Species 1986 1997 brook trout
N12 Reference T12 Taxonomy:8038