A brain and a head for a different habitat: size variation in four morphs of Arctic charr (Salvelinus alpinus (L.)) in a deep oligotrophic lake
Adaptive radiation is the diversification of species to different ecological niches and has repeatedly occurred in different salmonid fish of postglacial lakes. In Lake Tinnsjøen, one of the largest and deepest lakes in Norway, the salmonid fish, Arctic charr (Salvelinus alpinus (L.)), has likely ra...
| Main Authors: | , , , , |
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| Format: | Dataset |
| Language: | unknown |
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2021
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| Subjects: | |
| Online Access: | https://zenodo.org/record/5224306 https://doi.org/10.5061/dryad.15dv41nvt |
| Summary: | Adaptive radiation is the diversification of species to different ecological niches and has repeatedly occurred in different salmonid fish of postglacial lakes. In Lake Tinnsjøen, one of the largest and deepest lakes in Norway, the salmonid fish, Arctic charr (Salvelinus alpinus (L.)), has likely radiated within 9700 years after deglaciation into ecologically and genetically segregated Piscivore, Planktivore, Dwarf and Abyssal morphs in the pelagial, littoral, shallow-moderate profundal and deep-profundal habitats. We compared trait variation in the head shape, the eye and olfactory organs, as well as the volumes of five brain regions of these four Arctic charr morphs. We hypothesised that specific habitat characteristics have promoted divergent body, head and brain sizes related to utilized depth differing in environmental constraints (e.g. light, oxygen, pressure, temperature and food quality). The most important ecomorphological variables differentiating morphs were body length, habitat, optic tectum and eye area. The Abyssal morph living in the deepest areas of the lake had the smallest brain region volumes, head and eye size. Comparing the olfactory bulb with the optic tectum in size, it was larger in the Abyssal morph than in the Piscivore morph. The Piscivore and Planktivore morphs that use more illuminated habitats have the largest optic tectum volume, followed by the Dwarf. The observed differences in body size and sensory capacities in terms of vision and olfaction in shallow and deep-water morphs likely relates to foraging and mating habitats in Lake Tinnsjøen. Further seasonal and experimental studies of brain volume in polymorphic species are needed to test the role of plasticity and adaptive evolution behind the observed differences. We counted (N1) and measured the olfactory organs (1) and measured five brain regions (olfactory bulb (2), telencephalon (3), optic tectum (4), cerebellum (5), and hypothalamus (6). We measured the width (W) of each brain structure from the dorsal and ventral image ... |
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