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Coevolutionary causes and consequences of high-fidelity mimicry by a specialist brood parasite
Mimicry is often invoked as a classic demonstration of the power of natural selection. However, mimicry systems are diverse and the accuracy of mimicry, or mimetic fidelity, varies from crude to near-perfect. There is growing evidence that low-fidelity mimicry is the norm, with cases of high-fidelit...
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| Format: | Thesis |
| Language: | English |
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Department of Biological Sciences
2022
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| _version_ | 1867613285885411328 |
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| access_status_str | Open Access |
| author | Lund, Jess |
| author2 | Spottiswoode, Claire N |
| author_browse | Lund, Jess Spottiswoode, Claire N |
| author_facet | Spottiswoode, Claire N Lund, Jess |
| author_sort | Lund, Jess |
| collection | Thesis |
| description | Mimicry is often invoked as a classic demonstration of the power of natural selection. However, mimicry systems are diverse and the accuracy of mimicry, or mimetic fidelity, varies from crude to near-perfect. There is growing evidence that low-fidelity mimicry is the norm, with cases of high-fidelity mimicry being rarer. This is particularly evident in avian interspecific brood parasites, which are birds that lay their eggs in the nests of other species, or ‘hosts'. A possible rare example of a “perfect mimic” is the African cuckoo Cuculus gularis (a specialist parasite of fork-tailed drongos Dicrurus adsimilis) which, to the human eye, exhibits some of the most sophisticated mimicry seen in a brood parasite-host system. In this work, I quantify the degree of mimetic fidelity in this system and investigate its consequences on the two antagonists, using experimental, observational and genetic data I collected in the field in Zambia. In Chapter 1 I first define perfect mimicry, and explore how mimetic fidelity can be quantified. I then review the factors responsible for the variability in mimetic fidelity among different mimicry systems. In Chapter 2 I use quantitative measures of egg colour and pattern, from models that approximate avian vision, to show that mimicry of drongo eggs by African cuckoos is near-perfect. I subsequently use field experiments and simulations to show that a high degree of interclutch variation (egg ‘signatures') means that drongos still have the upper hand in the arms race against this near-perfect mimic. In Chapter 3 I investigate the genetic architecture of perfect mimicry by comparing cuckoo egg phenotypes to their mitochondrial DNA haplotypes, providing evidence that the African cuckoo likely shows bi-parental inheritance of egg phenotype. Together these results highlight the effectiveness of egg signatures as a defence against brood parasites, even when mimicry shows high accuracy and precision, and underline the role of mechanistic factors in enabling high-fidelity mimicry to evolve. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/35903 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:33:43.673Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2022 |
| publishDateRange | 2022 |
| publishDateSort | 2022 |
| publisher | Department of Biological Sciences |
| publisherStr | Department of Biological Sciences |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/35903 Coevolutionary causes and consequences of high-fidelity mimicry by a specialist brood parasite Lund, Jess Spottiswoode, Claire N Jamie, Gabriel A Biological Sciences Mimicry is often invoked as a classic demonstration of the power of natural selection. However, mimicry systems are diverse and the accuracy of mimicry, or mimetic fidelity, varies from crude to near-perfect. There is growing evidence that low-fidelity mimicry is the norm, with cases of high-fidelity mimicry being rarer. This is particularly evident in avian interspecific brood parasites, which are birds that lay their eggs in the nests of other species, or ‘hosts'. A possible rare example of a “perfect mimic” is the African cuckoo Cuculus gularis (a specialist parasite of fork-tailed drongos Dicrurus adsimilis) which, to the human eye, exhibits some of the most sophisticated mimicry seen in a brood parasite-host system. In this work, I quantify the degree of mimetic fidelity in this system and investigate its consequences on the two antagonists, using experimental, observational and genetic data I collected in the field in Zambia. In Chapter 1 I first define perfect mimicry, and explore how mimetic fidelity can be quantified. I then review the factors responsible for the variability in mimetic fidelity among different mimicry systems. In Chapter 2 I use quantitative measures of egg colour and pattern, from models that approximate avian vision, to show that mimicry of drongo eggs by African cuckoos is near-perfect. I subsequently use field experiments and simulations to show that a high degree of interclutch variation (egg ‘signatures') means that drongos still have the upper hand in the arms race against this near-perfect mimic. In Chapter 3 I investigate the genetic architecture of perfect mimicry by comparing cuckoo egg phenotypes to their mitochondrial DNA haplotypes, providing evidence that the African cuckoo likely shows bi-parental inheritance of egg phenotype. Together these results highlight the effectiveness of egg signatures as a defence against brood parasites, even when mimicry shows high accuracy and precision, and underline the role of mechanistic factors in enabling high-fidelity mimicry to evolve. 2022-03-04T08:05:17Z 2022-03-04T08:05:17Z 2021 2022-03-03T13:11:45Z Master Thesis Masters MSc http://hdl.handle.net/11427/35903 eng application/pdf Department of Biological Sciences Faculty of Science |
| spellingShingle | Biological Sciences Lund, Jess Coevolutionary causes and consequences of high-fidelity mimicry by a specialist brood parasite |
| thesis_degree_str | Master's |
| title | Coevolutionary causes and consequences of high-fidelity mimicry by a specialist brood parasite |
| title_full | Coevolutionary causes and consequences of high-fidelity mimicry by a specialist brood parasite |
| title_fullStr | Coevolutionary causes and consequences of high-fidelity mimicry by a specialist brood parasite |
| title_full_unstemmed | Coevolutionary causes and consequences of high-fidelity mimicry by a specialist brood parasite |
| title_short | Coevolutionary causes and consequences of high-fidelity mimicry by a specialist brood parasite |
| title_sort | coevolutionary causes and consequences of high fidelity mimicry by a specialist brood parasite |
| topic | Biological Sciences |
| url | http://hdl.handle.net/11427/35903 |
| work_keys_str_mv | AT lundjess coevolutionarycausesandconsequencesofhighfidelitymimicrybyaspecialistbroodparasite |