The anatomy of seismic signalling: morphological adaptations of the hind limb in drumming and non-drumming African mole-rats (Bathyergidae)
| dc.contributor.advisor | Kotze, Sanet H. | en_ZA |
| dc.contributor.advisor | Bennett, Nigel C. | en_ZA |
| dc.contributor.author | Sahd, Lauren | en_ZA |
| dc.contributor.other | Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Biomedical Sciences. Anatomy and Histology. | en_ZA |
| dc.date.accessioned | 2021-03-08T07:38:11Z | en_ZA |
| dc.date.accessioned | 2021-04-22T10:13:42Z | en_ZA |
| dc.date.available | 2021-12-31T03:00:12Z | en_ZA |
| dc.date.issued | 2021-03-31 | en_ZA |
| dc.description | Thesis (PhD)--Stellenbosch University, 2021. | en_ZA |
| dc.description.abstract | ENGLISH ABSTRACT: Hind foot drumming is one of the most common forms of seismic signalling. The family Bathyergidae (African mole-rats) is well known for exhibiting hind foot drumming during courtship and territorial behaviour. Hind foot drumming in bathyergid species arises as a result of the rapid flexion and extension of the hip and knee joints by either a single or alternating hind limbs. While the ecological context of drumming in these species has been well described, the possible morphological adaptations to enable the production of these seismic signals, have yet to be unravelled. Therefore, the primary aim of the present study was to investigate if morphologically discernible adaptations to the hind limb osteology and muscles could be determined in two drumming (Georychus capensis and Bathyergus suillus) and one non-drumming species (Cryptomys hottentotus natalensis) of African mole-rats using a variety of techniques. The gross anatomy of the hind limb was investigated by undertaking detailed dissections to determine the origin and insertion points as well as the innervation of the muscles of the hind limb. Thereafter, 32 muscles were removed from a single limb (with joint angles closest to 90°) for muscle architecture measurements which included belly length, muscle fascicle length, muscle mass and physiological cross-sectional area. The remaining soft tissue was removed from the specimens by maceration to enable the description of the osteology of the hind limb. Additionally, morpho-functional indices were used to morphometrically compare the bones between species. Twenty-one hind limb muscles were selected to undergo muscle fibre typing using myosin heavy chain slow antibody immunohistochemical staining. The amount of positive fibres was quantified to determine the total percentage of slow muscle fibres in each muscle section. Micro computed tomography (CT) scans of contrast enhanced stained specimens were used to determine accurate volumetric measurements of 26 muscles per sample in all three species as well as to assemble three dimensional reconstructions of the musculature of the limbs. Musculus gracilis anticus may play a key role in hind foot drumming as it was the only muscle that was morphologically different between the drummers and non-drummer. In the two drumming species, m. gracilis was a single muscle, whereas it was double in C. h. natalensis. Additionally, it was the only muscle to be significantly different in G. capensis and C. h. natalensis for all muscle architecture parameters analysed. Furthermore, m. gracilis anticus was the only muscle that had a significant difference in the volume as determined by the micro CT scans between the two drumming species and C. h. natalensis. However, the number of slow fibres of m. gracilis anticus was not significantly different between G. capensis and C. h. natalensis. Furthermore, the robust tibias in the drumming species, as indicated by the tibial robustness index, possibly counter the additional biomechanical load caused by the muscles (specifically m. gracilis anticus) involved with hind foot drumming. Thus, it can be concluded that there are distinct morphological adaptations to the osteology and musculature of the two hind foot drumming species. | en_ZA |
| dc.description.abstract | AFRIKAANS OPSOMMING: Dromming met die agtervoet is een van die mees algemene vorme van seismiese kommunikasie. Die familie Bathyergidae van Afrika molrotte is bekend daarvoor dat hulle met die agtervoet drom tydens hofmakery en territoriale gedrag. Dromming in die agtervoet by Bathyergidae word vergemaklik deur die vinnige fleksie en ekstensie van die heup- en kniegewrigte in een of alternatiewe agterste ledemate. Terwyl die ekologiese konteks van dromming by hierdie spesies goed beskryf is, moet moontlike morfologiese aanpassings om die produksie van seismiese seine moontlik te maaknog bepaal word. Daarom was die doel van die huidige studie om vas te stel of morfologies uitkenbare aanpassings vir agtervoetdromming in die osteologie en spiere van die agterste ledemate bepaal kon word in twee dromende (Georychus capensis en Bathyergus suillus) en een nie-dromende spesie (Cryptomys hottentotus natalensis) van Afrika molrotte deur verskillende tegnieke te gebruik. Die makroskopiese anatomie van die agterste ledemaat is bestudeer met behulp van gedetailleerde disseksies om die oorsprong en inplantings sowel as die senuvoorsiening van die spiere van die agterste ledemaat te bepaal. Daarna is 32 spiere van die ledemaat verwyder (met gewrigshoeke naby aan 90°) vir spierargitektuurmetings, insluitend buiklengte, spierfasikellengte, spiermassa en fisiologiese deursnee-area. Die oorblywende sagte weefsel is deur middel van maserasie van die bene verwyder en die osteologie van die agterste ledemaat is beskryf. Verder is morfo-funksionele indekse gebruik om die bene tussen spesies morfometries te vergelyk. Een-en-twintig agterbeen-spiere is gekies om spiervesel-tipering te ondergaan met behulp van immunohistochemiese kleuring deur die myosien-swaar ketting-stadige teenliggaam. Die hoeveelheid positiewe vesels is outomaties gekwantifiseer om die totale persentasie stadige spiervesels in elke spierseksie te bepaal. Mikro rekenaar tomografie (CT) skanderings van gekontrasteerde gekleurde monsters is gebruik om akkurate volumetriese metings van 26 spiere per spesie in al drie spesies te bepaal en om driedimensionele rekonstruksies van die spiere te skep. M. gracilis anticus kan 'n sleutelrol speel in die agtervoetdroming, want dit was die enigste spier wat morfologies verskil tussen die drommende en nie-drommende spesies. In die twee drommende spesies, was m. gracilis 'n enkele spier, terwyl dit dubbeld was in C. h. natalensis. Daarbenewens was dit die enigste spier wat beduidend van G. capensis en C. h. natalensis verskil het wat betref alle spierargitektuurparameters. Dit was ook die enigste spier met 'n beduidende verskil in die volume soos bepaal deur die mikro-CT-skanderings in die dromende spesies in vergelyking met C. h. natalensis. Die samestelling van die tipe spiervesels van m. gracilis anticus was nie beduidend verskillend tussen G. capensis en C. h. natalensis nie. Daarbenewens sal die robuuste tibias by die drommendepesies, soos aangedui deur die tibiale robuustheidsindeks, waarskynlik die addisionele biomeganiese lading wat veroorsaak word deur die spiere (spesifiek m. gracilis anticus) gedurende agtervoetdromming teenwerk.wat. Daar kan dus ‘n gevolgtrekking gemaak word dat daar morfologiese aanpassings is vir agtervoetdromming aan die osteologie en spiere van die drommende spesies. | af_ZA |
| dc.description.version | Doctorate | en_ZA |
| dc.embargo.terms | 2021-12-31 | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/10019.1/110315 | en_ZA |
| dc.language.iso | en_ZA | en_ZA |
| dc.publisher | Stellenbosch : Stellenbosch University, 2021. | en_ZA |
| dc.rights.holder | Stellenbosch University | en_ZA |
| dc.subject | Bathyergidae | en_ZA |
| dc.subject | Seismic signalling | en_ZA |
| dc.subject | Hindlimb -- Muscles | en_ZA |
| dc.subject | Rodents -- Morphology | en_ZA |
| dc.subject | UCTD | en_ZA |
| dc.title | The anatomy of seismic signalling: morphological adaptations of the hind limb in drumming and non-drumming African mole-rats (Bathyergidae) | en_ZA |
| dc.type | Thesis | en_ZA |