Intraspecific Energetic Trade-Offs and Costs of Encephalization Vary from Interspecific Relationships in Three Species of Mormyrid Electric Fishes
| Autor: | Bruce A. Carlson, Kimberley V. Sukhum, Megan K. Freiler |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
Biology
Intraspecific competition 03 medical and health sciences Behavioral Neuroscience 0302 clinical medicine Oxygen Consumption Developmental Neuroscience Species Specificity Animals Stabilizing selection Hypoxia 030304 developmental biology 0303 health sciences Energetics Encephalization Species diversity Brain Interspecific competition Organ Size Biological Evolution Evolutionary biology Brain size Basal metabolic rate Energy Metabolism 030217 neurology & neurosurgery Electric Fish |
| Zdroj: | Brain, behavior and evolution. 93(4) |
| ISSN: | 1421-9743 |
| Popis: | The evolution of increased encephalization comes with an energetic cost. Across species, this cost may be paid for by an increase in metabolic rate or by energetic trade-offs between the brain and other energy-expensive tissues. However, it remains unclear whether these solutions to deal with the energetic requirements of an enlarged brain are related to direct physiological constraints or other evolved co-adaptations. We studied the highly encephalized mormyrid fishes, which have extensive species diversity in relative brain size. We previously found a correlation between resting metabolic rate and relative brain size across species; however, it is unknown how this interspecific relationship evolved. To address this issue, we measured intraspecific variation in relative brain size, the sizes of other organs, metabolic rate, and hypoxia tolerance to determine if intraspecific relationships between brain size and organismal energetics are similar to interspecific relationships. We found that 3 species of mormyrids with varying degrees of encephalization had no intraspecific relationships between relative brain size and relative metabolic rate or relative sizes of other organs, and only 1 species had a relationship between relative brain size and hypoxia tolerance. These species-specific differences suggest that the interspecific relationship between metabolic rate and relative brain size is not the result of direct physiological constraints or strong stabilizing selection, but is instead due to other species level co-adaptations. We conclude that variation within species must be considered when determining the energetic costs and trade-offs underlying the evolution of extreme encephalization. |
| Databáze: | OpenAIRE |
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