Ontogenetic shifts in olfactory rosette morphology of the sockeye salmon,Oncorhynchus nerka |
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Authors: | Sarah E Rheinsmith Thomas P Quinn Andrew H Dittman Kara E Yopak |
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Institution: | 1. Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, North Carolina, USA;2. School of Aquatic and Fishery Sciences, University of Washington, Seattle, Washington, USA;3. Environmental and Fisheries Sciences Division, Northwest Fisheries Science Center, 4. National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, Washington, USA |
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Abstract: | Sockeye salmon, Oncorhynchus nerka, are anadromous, semelparous fish that breed in freshwater—typically in streams, and juveniles in most populations feed in lakes for 1 or 2 years, then migrate to sea to feed for 2 or 3 additional years, before returning to their natal sites to spawn and die. This species undergoes important changes in behavior, habitat, and morphology through these multiple life history stages. However, the sensory systems that mediate these migratory patterns are not fully understood, and few studies have explored changes in sensory function and specialization throughout ontogeny. This study investigates changes in the olfactory rosette of sockeye salmon across four different life stages (fry, parr, smolt, and adult). Development of the olfactory rosette was assessed by comparing total rosette size (RS), lamellae number, and lamellae complexity from scanning electron microscopy images across life stages, as a proxy for olfactory capacity. Olfactory RS increased linearly with lamellae number and body size (p < .001). The complexity of the rosette, including the distribution of sensory and nonsensory epithelia and the appearance of secondary lamellar folding, varied between fry and adult life stages. These differences in epithelial structure may indicate variation in odor-processing capacity between juveniles imprinting on their natal stream and adults using those odor memories in the final stages of homing to natal breeding sites. These findings improve our understanding of the development of the olfactory system throughout life in this species, highlighting that ontogenetic shifts in behavior and habitat may coincide with shifts in nervous system development. |
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Keywords: | neurobiology olfactory rosette ontogentic shifts sockeye Salmon |
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