Abstract
We test the effects of body mass and phylogeny on middle ear cavity pneumatization, and the role of pneumatization in hearing function, spanning the anatomical, ecological, and behavioral diversity of nonhuman primates. All cavities were segmented in middle ear scans of 96 specimens, from 12 strepsirrhine and 15 haplorhine extant species. We measured the tympanic cavity (TC) separately, and all other middle ear spaces together (MES), calculating the degree of pneumatization with the surface area-to-volume ratio. We tested body mass effect with linear regression; we evaluated the phylogenetic signal and selection patterns, using a Kappa statistic test, and Ornstein-Uhlenbeck models (OU). We investigated the link between pneumatization and hearing sensitivity using phylogenetic regression. Testing body mass reveals an allometric pattern for both TC and MES dimensions. Degree of pneumatization in MES is dependent on body mass in haplorhines: larger animals have more pneumatized MES. Differences at various taxonomic ranks were observed for MES, while no phylogenetic influence was observed for TC. Infraorder selection patterns are different. Auditory performance is significantly related to degree of pneumatization, indicating that a pneumatized middle ear is associated with better perception of low frequencies. Pneumatization in MES is under differential selective pressure, indicating several optima for this trait. Pneumatization in MES probably modifies hearing sensitivity through pressure regulation mechanisms, auditory bulla size reduction, and frequency modulation. This could explain strepsirrhine adaptation to high-frequency perception, while haplorhine auditory perception is adapted to a broader sound range, including high and low frequencies.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.