Metabolic traits of westslope cutthroat trout,introduced rainbow trout and their hybrids in an ecotonal hybrid zone along an elevation gradient |
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Authors: | JOSEPH B. RASMUSSEN MICHAEL D. ROBINSON ALICE HONTELA DANIEL D. HEATH |
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Affiliation: | 1. Department of Biological Sciences, University of Lethbridge, 4401 University Dr W Lethbridge, AB, T1K 3M4, Canada;2. Department of Biological Sciences, Great Lakes Institute for Environmental Research, University of Windsor, 401 Sunset Windsor Ontario, N9B?3P4, Canada |
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Abstract: | In the Upper Oldman River, Alberta, introduced non‐native hatchery rainbow trout (Oncorhynchus mykiss) hybridize with native westslope cutthroat trout (O. clarkii), resulting in a hybrid swarm. Rainbow trout dominate at low elevations (< 1250 m) in the river mainstem, cutthroat in high‐elevation tributaries (> 1400 m), and hybrids are numerically dominant in the mid‐elevation range. We hypothesized that metabolism of rainbow trout would exceed that of cutthroat trout, and that the elevation gradient in genetic makeup would be mirrored by a gradient in metabolic traits, with intermediate traits in the hybrid‐dominated ecotone. Metabolic traits were measured and regressed against the genetic makeup of individuals and elevation. Rainbow trout had higher oxygen consumption rates (OCRs), higher white muscle lactate dehydrogenase (LDH), and citrate synthase (CS) activity, and higher plasma acetylcholinesterase (AchE) than cutthroat trout. Hybrids had intermediate OCRs and AchE, but LDH activity as high as rainbow trout. While hybrid zones are usually modelled as a balance between cross species mating and selection against hybrids, ecotonal hybrid zones, where hybrids proliferate in intermediate habitats and have traits that appear well suited to ecotonal conditions, have been proposed for some plants and animals, and may have important implications for resource management and conservation. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 56–72. |
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Keywords: | acetylcholinesterase citrate synthase ecotone elevation hybrid zone introgression lactate dehydrogenase oxygen consumption |
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