Olfaction and scent discrimination in African elephants (Loxodonta africana)
| dc.contributor.advisor | Leslie, Alison J. | en_ZA |
| dc.contributor.advisor | Hoffman, Louwrens C. | en_ZA |
| dc.contributor.author | Von Dürckheim, Katharina EM | en_ZA |
| dc.contributor.other | Stellenbosch University. Faculty of AgriSciences. Dept. of Conservation Ecology and Entomology. | en_ZA |
| dc.date.accessioned | 2021-06-07T14:19:56Z | |
| dc.date.available | 2021-06-07T14:19:56Z | |
| dc.date.issued | 2021-04 | |
| dc.description | Thesis (PhDConsEcol)--Stellenbosch University, 2021. | en_ZA |
| dc.description.abstract | ENGLISH ABSTRACT: As an endangered mammal, novel research into the African elephant’s ethochemistry will assist ethologists, conservation biologists and wildlife managers in understanding odour signals in elephant exudates, and how they impact elephant behaviour in captivity and in the wild. Analytical methods combining genetics, statistics with SPME GC_MS and innovative metabolomics visualisation software are a useful first step in unlocking odours salient to elephant reproduction, breeding and behaviour. Mammals, such as the African elephant, which live in sophisticated, fission-fusion, social systems marked by linear dominance hierarchies and ritualized greeting ceremonies, require an effective means of communication in order to maintain social cohesion. A number of acoustic, olfactory and visual signals have been described. Within a group context, individuals need to discriminate between members of their group and foreign conspecifics in order to avoid inbreeding and to identify recipients of nepotistic behaviour. Such olfactory group/herd/clan/colony identity signals have been described in a number of mammals such as beavers, bats, naked mole rats, rabbits, fur seals, lemurs and hyena but are lacking in the iconic African elephant. It is to date not clear what fixed and variable information is encoded in African elephant urine, temporal gland secretions (TGS), genital and buccal secretions, and whether an olfactory signal for herd membership exists, although scientists have long expected this to be the case. Specifically, African elephant TGS, buccal and genital secretions in adult females have not been described in a free-ranging population. The overall objective of this research was to augment scientific understanding of African elephant olfactory behaviour in a multi-disciplinary way, combining behavioural observation and experimental trials of African elephants in sanctuaries in South Africa, with genetic and chemical data sampled from a free-ranging African elephant population during a translocation event in Malawi. The research first assesses olfactory acuity and scent discrimination ability in African elephants through novel behavioural bioassays. Subsequently, this study examines whether chemical signals in urine, TGS, buccal and genital secretions encode for age, sex and identity, and explores whether odour is correlated with genetic relatedness. For the first time, the chemistry in TGS, buccal and genital secretions is characterised in wild African elephant adult females (n=40). Elephants were found to be highly adept at scent-discriminating between humans, and scent- tracking a target human across various substrates, including distractor trails. Results suggest that elephants may utilise olfaction to discriminate between individual conspecifics. This was tested using behavioural bioassays, which concluded that African elephants can discriminate between unfamiliar and familiar conspecifics from both urine and dung. Urine elicited the most interest, and was used for further detailed analysis using the comprehensive metabolomics tool XCMS online. TGS, buccal and genital secretions from wild-sampled elephants (n=113) were found to encode individual identity in African elephants. TGS and buccal secretions encoded for age, and TGS and genital secretions tended towards significance for sex. Genetic relatedness was not correlated with odour in TGS, buccal and genital secretions at the herd level. However in all three odours, Similarity Percentage Analysis (SIMPER) identified “herd” as a highly significant factor in explaining chemical differences between herds. This suggests that group odour in African elephants is not correlated to genetic relatedness at the population, herd and individual level, and allows for the possibility that bacteria may be involved in group odour. The biomarkers alkan-2-ones and alkan-2-ols previously published in association with elephant male urinary microbial communities, were identified in adult female buccal and labial secretions. SIMPER analyses further extracted a number of short-chain fatty acids significant to chemical differences between groups (notably acetic acid, pentanoic acid, hexanoic acid, decanoic acid, dodecanoic acid and tetradecanoic acid). These and other compounds have been identified in similar studies as key volatile compounds from bacterial fermentation in clan-living hyenas and colonially-living meerkats, further supporting this possibility. The frequent affiliative social behaviour of African elephants is posited as a likely mechanism for bacterial transmission. Conservation objectives can be supported by an improved understanding of how chemical communication in social mammals like elephants influences mate choice, establishing social relationships, courting, mating and the use of scent for establishing territories. In African elephants, an improved understanding of elephant semiochemistry and eliciting behaviour could shed light on scent manipulation for elephant translocation and reintroductions, captive breeding, welfare and enrichment protocols, human elephant conflict (HEC), elephant reintroductions, social behaviour and habitat selection. | en_ZA |
| dc.description.abstract | AFRIKAANSE OPSOMMING: Vir 'n bedreigde soogdier, sal nuwe navorsing oor die etochemie van die Afrika-olifant, etoloë, bewaringsbioloë en natuurlewebestuurders help om reukspore in olifante-eksudate te verstaan, en hoe sulke -spore die gedrag van olifante in aanhouding en in die natuur kan beïnvloed. Analitiese benaderings wat genetika, statistieke met vaste fase mikro-ekstraksie gevolg deur gaschromatografie-massaspektrometrie (SPME-GC-MS) en innoverende sagteware vir visualisering van metabolomika kombineer, is 'n nuttige eerste stap in die ontsluiting van reukspore wat opvallend is vir reproduksie, teling en gedrag van olifante. Soogdiere, soos die Afrika-olifant (AO), wat in gesofistikeerde sosiale stelsels leef wat gekenmerk word deur lineêre dominansie hiërargieë en geritualiseerde groetplegtighede, benodig 'n effektiewe kommunikasiemiddel om sosiale kohesie te handhaaf. 'n Aantal akoestiese, reuk- en visuele spore is beskryf. Binne groepsverband moet individue onderskei tussen lede van hul groep en vreemde lede om inteling te vermy en om ontvangers van nepotistiese gedrag te identifiseer. Sulke reukspore vir groep/kudde/stam/kolonie identiteitsseine is beskryf in 'n aantal soogdiere soos bewers, vlermuise, naakte molrotte, konyne, pelsrobbe, lemurs en hiënas, maar dit ontbreek vir die ikoniese AO. Dit is tot dusver nie duidelik watter vaste en veranderlike inligting in AO-uriene, temporale klier- (TGS), geslags- en bukkale afskeidings gekodeer is nie. Meer spesifiek, AO TGS, bukkale- en geslagsafskeidings by volwasse olifantkoeie is nie in 'n vrylopende AO-populasie gekwantifiseer nie. Dit is ook onduidelik of daar 'n reukspoor vir kuddelidmaatskap bestaan, hoewel wetenskaplikes dit al lank vermoed het. Die oorkoepelende doel van hierdie navorsing was om die wetenskaplike begrip van die olifaktoriese gedrag van Afrika-olifante te verbeter deur 'n multidissiplinêre benadering te gebruik, wat gedragswaarneming en eksperimentele proewe met Afrika olifante in toevlugsoorde in Suid-Afrika kombineer, met genetiese en chemiese gegewens uit 'n vrylopende olifantpopulasie tydens 'n translokasie-geleentheid in Malawi. Die navorsing beoordeel eers reukskerpte en reukdiskriminasievermoë by Afrika-olifante deur middel van nuwe gedrag bio-bepalingsmetodes. Vervolgens word hierdie studie ondersoek of chemiese seine in uriene, TGS, bukkale- en geslagsafskeidings kodeer vir ouderdom, geslag en identiteit; en daar was ook ondersoek of reuk verband hou met genetiese verwantskap. Vir die eerste keer is die chemiese aspekte in TGS, bukkale- en geslagsafskeidings in 41 wilde volwasse AE- wyfies gekenmerk. Daar is gevind dat olifante hoogs vaardig is in die reuk-onderskeiding tussen mense en die reuk-opsporing van 'n teikenmens oor verskillende soorte substrate, insluitend afleidingspore. Resultate dui daarop dat olifante olfaksie kan gebruik om onderskeid tussen gelyksoortige individue te onderskei. Dit is getoets aan die hand van gedrag biobepalings, wat tot die gevolgtrekking gekom het dat Afrika-olifante onderskeid kan tref tussen onbekende en bekende gelyksoortige individue deur beide uriene en mis. Uriene het die meeste belangstelling ontlok en is gebruik vir verdere gedetailleerde ontledings met behulp van die omvattende aanlyn metabolomika-instrument XCMS. Analises van TGS, bukkale- en genitale afskeidings van 113 wilde AO het aangedui dat kodering vir individuele identiteit in AO voorkom. Analises het aangedui dat afskeidings van die temporale en bukkale kliere wat vir ouderdom gekodeer is, en TGS en genitale afskeidings geneig is om te kodeer vir geslag. Genetiese verwantskap was nie gekorreleer met reuk in TGS, bukkale- en geslagsafskeidings op kuddevlak nie. In al drie reuke, het 'n soortgelyke persentasie-analise (SIMPER) 'kudde' geïdentifiseer as 'n baie belangrike faktor om chemiese verskille tussen kuddes te verklaar. Dit dui daarop dat groepsreuk by Afrika- olifante nie gekoppel is aan genetiese verwantskap op populasie-, kudde- en individuele vlak nie en dit moontlik maak dat bakterieë by groepsreuk betrokke kan wees. Die biomerkers alkan- 2-ene en alkan-2-ols, wat voorheen gepubliseer is ten opsigte van olifantbul urien mikrobiese gemeenskappe, is geïdentifiseer in volwasse vroulike bukkale en labiale afskeidings. SIMPER- ontledings het 'n aantal kortkettingvetsure wat veral chemiese verskille tussen groepe verklaar (veral asynsuur, pentansuur, heksaansuur, dekanoësuur, dodekanoësuur en tetradekanoïensuur) onttrek. Hierdie en ander verbindings is in soortgelyke studies geïdentifiseer as die belangrikste vlugtige verbindings van bakteriële fermentasie in stamlewende hiënas en koloniale lewende meerkatte, wat hierdie moontlikheid verder ondersteun. Die gereelde affiliatiewe sosiale gedrag van AO word beskou as 'n waarskynlike meganisme vir bakteriële oordrag. Bewaringsdoelstellings kan ondersteun word deur 'n beter begrip van hoe chemiese kommunikasie by sosiale soogdiere soos olifante, die keuse van die maat, vestiging van sosiale verhoudings, hofmaak, paring en die gebruik van reuk vir die vestiging van gebiede, beïnvloed. By Afrikaanse olifante is 'n beter begrip van olifant semio- chemie en verwante gedrag kan hulp verleen met die verskuiwing en herbekendstelling van olifante, teling in aanhouding, welsyn- en verykingsprotokolle, bestuur van mens-olifant konflik, sosiale gedrag en kies van habitat. | af_ZA |
| dc.description.version | Doctoral | en_ZA |
| dc.format.extent | xvi, 172 pages : illustrations (some color) | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/10019.1/110578 | |
| dc.language.iso | en_ZA | en_ZA |
| dc.publisher | Stellenbosch : Stellenbosch University | en_ZA |
| dc.rights.holder | Stellenbosch University | en_ZA |
| dc.subject | African elephants (Loxodonta africana) -- Behavior | en_ZA |
| dc.subject | Olfaction | en_ZA |
| dc.subject | Wildlife management | en_ZA |
| dc.subject | Smell | en_ZA |
| dc.subject | UCTD | en_ZA |
| dc.title | Olfaction and scent discrimination in African elephants (Loxodonta africana) | en_ZA |
| dc.type | Thesis | en_ZA |