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Edwards S, Bessinger R. Morphological variations of auditory bullae in otomyine rodents (Rodentia: Otomyini) in southern African biomes. J Morphol 2024; 285:e21680. [PMID: 38361274 DOI: 10.1002/jmor.21680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 12/12/2023] [Accepted: 01/15/2024] [Indexed: 02/17/2024]
Abstract
Mammalian middle ear cavities differ from those of other taxa as they comprise three ossicles and in rodents, can be encapsulated by an auditory bulla. In small mammals, the middle ear cavity (bulla) was found to be enlarged in the desert-dwelling species; however, differences in bullar size could have been due to ancestry. In this study, we sampled seven species from three genera (Myotomys, Otomys, and Parotomys) of the African murid tribe Otomyini (laminated-toothed rats), and compared the bullar volumes and shapes between the otomyine species and within the species Myotomys unisulcatus. Photographs of museum skull specimens were taken from ventral and lateral views, and the volumes of the bullae were estimated digitally from the photographs. No sexual dimorphism in bullar volumes was found in any of the species. Corrected bullar volumes were significantly different between species and larger bullae were seen in individuals inhabiting regions with lower annual rainfall. Bullar shape (estimated using geometric morphometrics) was significantly different between the genera and the species. Parotomys have tympanic meatuses that face more anteriorly compared to both, Otomys and Myotomys. When comparing bullae within M. unisulcatus, those inhabiting regions with lower annual rainfall had significantly larger bullar volumes, but no significant difference was found in bullar shape between the regions. This study shows that otomyine rodents in more xeric habitats have different auditory structures to those inhabiting wetter habitats.
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Affiliation(s)
- Shelley Edwards
- Department of Zoology and Entomology, Rhodes University, Makhanda, South Africa
| | - Rochelle Bessinger
- Department of Zoology and Entomology, Rhodes University, Makhanda, South Africa
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Vaglietti S, Villeri V, Dell’Oca M, Marchetti C, Cesano F, Rizzo F, Miller D, LaPierre L, Pelassa I, Monje FJ, Colnaghi L, Ghirardi M, Fiumara F. PolyQ length-based molecular encoding of vocalization frequency in FOXP2. iScience 2023; 26:108036. [PMID: 37860754 PMCID: PMC10582585 DOI: 10.1016/j.isci.2023.108036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 07/18/2023] [Accepted: 09/21/2023] [Indexed: 10/21/2023] Open
Abstract
The transcription factor FOXP2, a regulator of vocalization- and speech/language-related phenotypes, contains two long polyQ repeats (Q1 and Q2) displaying marked, still enigmatic length variation across mammals. We found that the Q1/Q2 length ratio quantitatively encodes vocalization frequency ranges, from the infrasonic to the ultrasonic, displaying striking convergent evolution patterns. Thus, species emitting ultrasonic vocalizations converge with bats in having a low ratio, whereas species vocalizing in the low-frequency/infrasonic range converge with elephants and whales, which have higher ratios. Similar, taxon-specific patterns were observed for the FOXP2-related protein FOXP1. At the molecular level, we observed that the FOXP2 polyQ tracts form coiled coils, assembling into condensates and fibrils, and drive liquid-liquid phase separation (LLPS). By integrating evolutionary and molecular analyses, we found that polyQ length variation related to vocalization frequency impacts FOXP2 structure, LLPS, and transcriptional activity, thus defining a novel form of polyQ length-based molecular encoding of vocalization frequency.
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Affiliation(s)
- Serena Vaglietti
- Rita Levi Montalcini Department of Neuroscience, University of Turin, 10125 Turin, Italy
| | - Veronica Villeri
- Rita Levi Montalcini Department of Neuroscience, University of Turin, 10125 Turin, Italy
| | - Marco Dell’Oca
- Rita Levi Montalcini Department of Neuroscience, University of Turin, 10125 Turin, Italy
| | - Chiara Marchetti
- Rita Levi Montalcini Department of Neuroscience, University of Turin, 10125 Turin, Italy
| | - Federico Cesano
- Department of Chemistry, University of Turin, 10125 Turin, Italy
| | - Francesca Rizzo
- Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Kowloon Tong, Hong Kong SAR 518057, China
| | - Dave Miller
- Cascades Pika Watch, Oregon Zoo, Portland, OR 97221, USA
| | - Louis LaPierre
- Deptartment of Natural Science, Lower Columbia College, Longview, WA 98632, USA
| | - Ilaria Pelassa
- Rita Levi Montalcini Department of Neuroscience, University of Turin, 10125 Turin, Italy
| | - Francisco J. Monje
- Department of Neurophysiology and Neuropharmacology, Medical University of Vienna, 1090 Vienna, Austria
| | - Luca Colnaghi
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy
- School of Medicine, Vita-Salute San Raffaele University, 20132 Milan, Italy
| | - Mirella Ghirardi
- Rita Levi Montalcini Department of Neuroscience, University of Turin, 10125 Turin, Italy
| | - Ferdinando Fiumara
- Rita Levi Montalcini Department of Neuroscience, University of Turin, 10125 Turin, Italy
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Heffner RS, Koay G, Heffner HE, Mason MJ. Hearing in African pygmy hedgehogs (Atelerix albiventris): audiogram, sound localization, and ear anatomy. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2022; 208:653-670. [PMID: 36282301 DOI: 10.1007/s00359-022-01579-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 08/21/2022] [Accepted: 09/24/2022] [Indexed: 12/14/2022]
Abstract
The behavioral audiogram and sound localization performance, together with the middle and inner ear anatomy, were examined in African pygmy hedgehogs Atelerix albiventris. Their auditory sensitivity at 60 dB SPL extended from 2 to 46 kHz, revealing a relatively narrow hearing range of 4.6 octaves, with a best sensitivity of 21 dB at 8 kHz. Their noise-localization acuity around the midline (minimum audible angle) was 14°, matching the mean of terrestrial mammals. The African pygmy hedgehog was not able to localize low-frequency pure tones or a 3-kHz amplitude-modulated tone when forced to rely on the interaural phase-difference cue, a trait shared by at least nine other mammals. The middle ear of Atelerix has a configuration including an ectotympanic which is not fused to the surrounding bones, a substantial pars flaccida, a synostosed malleo-ectotympanic articulation and a 'microtype' malleus. The hearing and sound localization of A. albiventris is compared to that of a broad range of other mammals. It is shown that a malleus morphology like that of Atelerix, including a stiff articulation with the ectotympanic, is a consistent feature of other mammals that do not hear frequencies below 400 Hz.
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Affiliation(s)
- Rickye S Heffner
- Department of Psychology, University of Toledo, Toledo, OH, 43606, USA.
| | - Gimseong Koay
- Department of Psychology, University of Toledo, Toledo, OH, 43606, USA
| | - Henry E Heffner
- Department of Psychology, University of Toledo, Toledo, OH, 43606, USA
| | - Matthew J Mason
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, CB2 3EG, UK
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Onley IR, Moseby KE, Austin JJ, Sherratt E. Morphological variation in skull shape and size across extinct and extant populations of the greater stick-nest rat (Leporillus conditor): implications for translocation. AUSTRALIAN MAMMALOGY 2022. [DOI: 10.1071/am21047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Taylor MC, Travouillon KJ, Andrew ME, Fleming PA, Warburton NM. Keeping an ear out: size relationship of the tympanic bullae and pinnae in bandicoots and bilbies (Marsupialia: Peramelemorphia). Curr Zool 2021; 68:251-264. [PMID: 35592340 PMCID: PMC9113346 DOI: 10.1093/cz/zoab055] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Accepted: 07/05/2021] [Indexed: 11/21/2022] Open
Abstract
Bandicoots and bilbies (Order Peramelemorphia) occupy a broad range of habitats across Australia and New Guinea, from open, arid deserts to dense forests. This once diverse group has been particularly vulnerable to habitat loss and introduced eutherian predators, and numerous species extinctions and range retractions have occurred. Understanding reasons for this loss requires greater understanding of their biology. Morphology of the pinnae and tympanic bullae varies markedly among species. As hearing is important for both predator avoidance and prey location, the variability in ear morphology could reflect specialization and adaptation to specific environments, and therefore be of conservation relevance. We measured 798 museum specimens representing 29 species of Peramelemorphia. Controlling for phylogenetic relatedness and head length, pinna surface area was weakly negatively correlated with average precipitation (rainfall being our surrogate measure of vegetation productivity/complexity), and there were no environmental correlates with effective diameter (pinna width). Controlling for phylogenetic relatedness and skull length, tympanic bulla volume was negatively correlated with precipitation. Species that inhabited drier habitats, which would be open and allow sound to carry further with less obstruction, had relatively larger pinnae and tympanic bullae. In contrast, species from higher rainfall habitats, where sounds would be attenuated and diffused by dense vegetation, had the smallest pinnae and bullae, suggesting that low-frequency hearing is not as important in these habitats. Associations with temperature did not reach statistical significance. These findings highlight linkages between hearing traits and habitat that can inform conservation and management strategies for threatened species.
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Affiliation(s)
- Melissa C Taylor
- Terrestrial Ecosystem Science and Sustainability, Harry Butler Institute, Murdoch University, 90 South St, Murdoch, WA 6150, Australia
- Collections and Research, Western Australian Museum, Welshpool, WA 6106, Australia
| | - Kenny J Travouillon
- Collections and Research, Western Australian Museum, Welshpool, WA 6106, Australia
| | - Margaret E Andrew
- Terrestrial Ecosystem Science and Sustainability, Harry Butler Institute, Murdoch University, 90 South St, Murdoch, WA 6150, Australia
| | - Patricia A Fleming
- Terrestrial Ecosystem Science and Sustainability, Harry Butler Institute, Murdoch University, 90 South St, Murdoch, WA 6150, Australia
| | - Natalie M Warburton
- Terrestrial Ecosystem Science and Sustainability, Harry Butler Institute, Murdoch University, 90 South St, Murdoch, WA 6150, Australia
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