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Variations in cochlea shape reveal different evolutionary adaptations in primates and rodents
Joaquin Del Rio1,2, Roxana Taszus3, Manuela Nowotny3
1Department of Archaeogenetics, Max Planck Institute for Evolutionary Anthropology, 04103, Leipzig, Germany. delrio@shh.mpg.de.
Scientific Reports
|February 8, 2023
Summary
Mammalian cochlear shape significantly impacts hearing abilities. Rodents evolved "tower-shaped" cochleae for low-frequency hearing, while primates developed wider cochleae for high-frequency hearing.
Area of Science:
- Evolutionary biology
- Comparative anatomy
- Bioacoustics
Background:
- The coiled cochlea is a defining feature of therian mammals.
- Existing research links cochlear morphology to hearing, but comprehensive understanding, especially controlling for body size, is lacking.
Purpose of the Study:
- To investigate the relationship between cochlear shape and hearing capacities in Euarchontoglires mammals, minimizing body size effects.
- To explore distinct morpho-evolutionary pathways in primates and rodents.
Main Methods:
- Utilized micro-CT scans and 3D geometric morphometrics to analyze cochlear shape in 33 therian mammal species.
- Developed phylogenetically corrected models linking cochlear shape data with 12 hearing variables from existing literature.
Main Results:
- Significant differences in cochlear shape were observed across different taxonomic groups within Euarchontoglires.
- These shape variations correlate with distinct hearing capacities, even with similar cochlear lengths.
- Rodents with enhanced low-frequency hearing exhibit more coiled, "tower-shaped" cochleae.
- Primates possess wider cochleae and demonstrate superior high-frequency hearing.
Conclusions:
- Cochlear shape diversification reflects specialized auditory adaptations in mammals.
- Primates and rodents have followed divergent evolutionary paths to enhance their hearing capabilities.
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