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Dixit T, Lund J, Fulford AJC, Apostol AL, Chen KC, Tong W, Feeney WE, Hamusikili L, Colebrook-Robjent JFR, Town CP, Spottiswoode CN. Chase-away evolution maintains imperfect mimicry in a brood parasite-host system despite rapid evolution of mimics. Nat Ecol Evol 2023; 7:1978-1982. [PMID: 37872417 PMCID: PMC10697838 DOI: 10.1038/s41559-023-02232-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Accepted: 09/19/2023] [Indexed: 10/25/2023]
Abstract
We studied a brood parasite-host system (the cuckoo finch Anomalospiza imberbis and its host, the tawny-flanked prinia Prinia subflava) to test (1) the fundamental hypothesis that deceptive mimics evolve to resemble models, selecting in turn for models to evolve away from mimics ('chase-away evolution') and (2) whether such reciprocal evolution maintains imperfect mimicry over time. Over only 50 years, parasites evolved towards hosts and hosts evolved away from parasites, resulting in no detectible increase in mimetic fidelity. Our results reflect rapid adaptive evolution in wild populations of models and mimics and show that chase-away evolution in models can counteract even rapid evolution of mimics, resulting in the persistence of imperfect mimicry.
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Affiliation(s)
- Tanmay Dixit
- Department of Zoology, University of Cambridge, Cambridge, UK.
- DST-NRF Centre of Excellence at the FitzPatrick Institute of African Ornithology, University of Cape Town, Rondebosch, South Africa.
| | - Jess Lund
- Department of Zoology, University of Cambridge, Cambridge, UK
- DST-NRF Centre of Excellence at the FitzPatrick Institute of African Ornithology, University of Cape Town, Rondebosch, South Africa
| | | | | | - Kuan-Chi Chen
- Computer Laboratory, University of Cambridge, Cambridge, UK
| | - Wenfei Tong
- Department of Zoology, University of Cambridge, Cambridge, UK
| | - William E Feeney
- Behavioural and Evolutionary Ecology Group, Doñana Biological Station (CSIC), Seville, Spain
- Department of Biosciences, Durham University, Durham, UK
| | | | | | | | - Claire N Spottiswoode
- Department of Zoology, University of Cambridge, Cambridge, UK
- DST-NRF Centre of Excellence at the FitzPatrick Institute of African Ornithology, University of Cape Town, Rondebosch, South Africa
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Dixit T, Chen KC, Stoddard MC, Mahadevan L, Town CP, Spottiswoode CN. Repeatable randomness, invariant properties, and the design of biological signatures of identity. Evolution 2023; 77:2224-2233. [PMID: 37482374 DOI: 10.1093/evolut/qpad134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 05/22/2023] [Accepted: 07/21/2023] [Indexed: 07/25/2023]
Abstract
What makes a perfect signature? Optimal signatures should be consistent within individuals and distinctive between individuals. In defense against avian brood parasitism, some host species have evolved "signatures" of identity on their eggs, comprising interindividual variation in color and pattern. Tawny-flanked prinia (Prinia subflava) egg signatures facilitate recognition and rejection of parasitic cuckoo finch (Anomalospiza imberbis) eggs. Here, we show that consistency and distinctiveness of patterns are negatively correlated in prinia eggs, perhaps because non-random, repeatable pattern generation mechanisms increase consistency but limit distinctiveness. We hypothesize that pattern properties which are repeatable within individuals but random between individuals ("invariant properties") allow hosts to circumvent this trade-off. To find invariant properties, we develop a method to quantify entire egg phenotypes from images taken from different perspectives. We find that marking scale (a fine-grained measure of size), but not marking orientation or position, is an invariant property in prinias. Hosts should therefore use differences in marking scale in egg recognition, but instead field experiments show that these differences do not predict rejection of conspecific eggs by prinias. Overall, we show that invariant properties allow consistency and distinctiveness to coexist, yet receiver behavior is not optimally tuned to make use of this information.
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Affiliation(s)
- Tanmay Dixit
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
- DST-NRF Centre of Excellence at the FitzPatrick Institute of African Ornithology, University of Cape Town, Rondebosch, Cape Town, South Africa
| | - Kuan-Chi Chen
- Computer Laboratory, University of Cambridge, Cambridge, United Kingdom
| | - Mary Caswell Stoddard
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, United States
| | - Lakshminarayanan Mahadevan
- School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, United States
- Department of Physics, Harvard University, Cambridge, MA, United States
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, United States
| | | | - Claire N Spottiswoode
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
- DST-NRF Centre of Excellence at the FitzPatrick Institute of African Ornithology, University of Cape Town, Rondebosch, Cape Town, South Africa
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Dixit T, Apostol AL, Chen KC, Fulford AJC, Town CP, Spottiswoode CN. Visual complexity of egg patterns predicts egg rejection according to Weber's law. Proc Biol Sci 2022; 289:20220710. [PMID: 35858060 PMCID: PMC9277300 DOI: 10.1098/rspb.2022.0710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Visual complexity is ubiquitous in nature. Drivers of complexity include selection in coevolutionary arms races between antagonists. However, the causes and consequences of biological complexity and its perception are largely understudied, partly because complexity is difficult to quantify. Here, we address this by studying egg pattern complexity and its perception in hosts (tawny-flanked prinia Prinia subflava), which visually recognize and reject mimetic eggs of their virulent brood parasite (cuckoo finch Anomalospiza imberbis). Using field data and an optimization algorithm, we compute a complexity metric which predicts rejection of experimentally placed conspecific eggs in prinia nests. Real cuckoo finch eggs exhibit significantly lower pattern complexity than prinia eggs, suggesting that high complexity benefits hosts because it distinguishes host eggs from parasitic eggs. We show that prinias perceive complexity differences according to Weber's law of proportional processing (i.e. relative, rather than absolute, differences between stimuli are processed in discrimination, such that two eggs with simple patterns are more easily discriminable than two with complex patterns). This may influence coevolutionary trajectories of hosts and parasites. The new methods presented for quantifying complexity and its perception can help us to understand selection pressures driving the evolution of complexity and its consequences for species interactions.
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Affiliation(s)
- Tanmay Dixit
- Department of Zoology, University of Cambridge, Cambridge, UK
| | | | - Kuan-Chi Chen
- Computer Laboratory, University of Cambridge, Cambridge, UK
| | | | | | - Claire N. Spottiswoode
- Department of Zoology, University of Cambridge, Cambridge, UK,DST-NRF Centre of Excellence at the FitzPatrick Institute of African Ornithology, University of Cape Town, Rondebosch, Cape Town, South Africa
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