Scents and scentability: an investigation into the chemical crypsis of the Puff Adder (Bitis arietans)
| dc.contributor.author | Miller, Ashadee Kay | |
| dc.date.accessioned | 2023-02-13T10:12:14Z | |
| dc.date.available | 2023-02-13T10:12:14Z | |
| dc.date.issued | 2022 | |
| dc.description.abstract | Few documented examples of chemical crypsis exist. This is in part due to the long-standing dogma that no organism can be truly chemically cryptic due to associated, odorous metabolic by-products, and in part due to our own limitations as vision-orientated organisms. Visual crypsis, in comparison, is a widely documented phenomenon. This adaptation is driven by selection pressures inherent in predator-prey arms races between prey and their vision-orientated predators. Yet, despite the prevalence of macrosmatic, scent-orientated predator species and their associated ability to exert similar selection pressures, the potential for chemical crypsis among species has and continues to be largely dismissed. The aim of this thesis was to more closely examine the chemical crypsis of the puff adder (Bitis arietans) and in so doing, contribute to an area of chemical ecology that is in its infancy. Currently, this extreme ambush predator serves as the only documented case of a chemically cryptic terrestrial vertebrate and the mechanisms driving this crypsis remain elusive. As such, I was afforded the novel opportunity to investigate not only the extent to which the puff adder’s chemical crypsis applies, but to also assess two potential mechanisms driving their chemical crypsis, namely the down regulation of associated microbiota and metabolic suppression as a means of controlling associated, odorous metabolic by-products. By using two considered biosensor species, the African elephant (Loxodonta Africana) and the snouted cobra (Naja annulifera), I demonstrate, using scent matching and y-maze techniques respectively, that the puff adder’s chemical crypsis is broadly applicable and in clear defiance of previously accepted dogma of chemical crypsis being an impossibility. In addition, I demonstrate using culture-dependent techniques and DNA sequencing that the puff adder does not downregulate its associated microbiota as a means of achieving chemical crypsis, but rather, that several microbial species closely associated with their trachea and dorsal scales may indeed directly contribute towards their chemical crypsis via their own odour degradation abilities. Furthermore, the notion that this extreme ambushing snake achieves chemical crypsis by means of metabolic suppression is rejected. Using closed-system respirometry, I demonstrate that the puff adder’s standard metabolic rate is not lower than those of several other species of snake, including those known to be odorous. Lastly, solid-phase micro-extraction and gas chromatography-mass spectrometry provide important insights into the puff adder’s volatilome, demonstrating that it is predominated by non-odorous alkanes and that the presence of a known odour-absorbing, waxy carboxylic acid found on the surfaces of the adder’s scale may serve to trap odorous substances. Though I have been unsuccessful in elucidating a specific mechanism underlying the puff adder’s chemical crypsis, this thesis provides the groundwork for more targeted research questions that may achieve such ends. | |
| dc.description.librarian | TL (2023) | |
| dc.description.statementofresponsibility | A thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the Faculty of Science, School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg, 2022 | |
| dc.faculty | Faculty of Science | |
| dc.identifier.uri | https://hdl.handle.net/10539/34478 | |
| dc.language.iso | en | |
| dc.phd.title | PhD | |
| dc.school | School of Animal, Plant and Environmental Sciences | |
| dc.title | Scents and scentability: an investigation into the chemical crypsis of the Puff Adder (Bitis arietans) | |
| dc.type | Thesis |