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Müllerian mimicry: an examination of Fisher's theory of gradual evolutionary change
Stockholm University, Faculty of Science, Department of Zoology.ORCID iD: 0000-0002-8708-8097
Stockholm University, Faculty of Science, Department of Zoology.
2005 (English)In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, Vol. 272, 2269-2275 p.Article in journal (Refereed) Published
Abstract [en]

In 1927, Fisher suggested that Müllerian mimicry evolution could be gradual and driven by predator generalization. A competing possibility is the so-called two-step hypothesis, entailing that Müllerian mimicry evolves through major mutational leaps of a less-protected species towards a better-protected, which sets the stage for coevolutionary fine-tuning of mimicry. At present, this hypothesis seems to be more widely accepted than Fisher’s suggestion. We conducted individual-based simulations of communities with predators and two prey types to assess the possibility of Fisher’s process leading to a common prey appearance. We found that Fisher’s process worked for initially relatively similar appearances. Moreover, by introducing a predator spectrum consisting of several predator types with different ranges of generalization, we found that gradual evolution towards mimicry occurred also for large initial differences in prey appearance. We suggest that Fisher’s process together with a predator spectrum is a realistic alternative to the two-step hypothesis and, furthermore, that it has fewer problems with purifying selection.  We also examined factors influencing gradual evolution towards mimicry and found that not only the relative benefits from mimicry but also the mutational schemes of the prey types matter.

Place, publisher, year, edition, pages
2005. Vol. 272, 2269-2275 p.
Keyword [en]
Müllerian mimicry, two-step hypothesis, predator spectrum, advergence, coevolution
Research subject
URN: urn:nbn:se:su:diva-29085DOI: 10.1098/rspb.2005.3227OAI: diva2:229091
Available from: 2009-08-11 Created: 2009-08-11 Last updated: 2014-10-13Bibliographically approved
In thesis
1. Predator psychology and mimicry evolution - a theoretical analysis
Open this publication in new window or tab >>Predator psychology and mimicry evolution - a theoretical analysis
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The evolution of Müllerian mimicry depends on many factors, among which predator psychology is the most important one. Predator avoidance learning, generalization and discrimination are primary selective agents during the evolutionary process. This thesis investigates an issue that has been a matter of debate since the 19th century; the question of how a mutant of a potential mimic population can escape the apostatic selection caused by predators that neither recognize it as a member of its own population, nor as being similar to its future model. In paper I, we investigate one of the ideas concerning this issue. Fisher stated that mimicry can evolve gradually by the displacement of an adaptive peak in a fitness landscape. We find this to be a plausible scenario, under certain conditions regarding predator generalization. In paper II, we further investigate the gradual evolutionary process and the implications of different generalization gradients. We find that the gradual process might be even more general than has previously been assumed and that abundant genetic variation in prey populations is an important factor in combination with predator generalization. In paper III, we examine another suggested solution to the problem of apostatic selection, the so-called two-step process, which can be problematic to extend to multiple prey traits. We find that the two-step process works for multidimensional traits provided that predators use feature-based generalization. The selective landscape of mimicry evolution is also shaped by the cost-benefit relationships for models and mimics. In paper IV we explore this matter, by applying the Rescorla-Wagner theory of learning to mimicry. We find that if variation in prey unpalatability gives rise to surprise, the learning rate is increased. This leads to unexpected kinds of mimicry that are more mutualistic than Müllerian mimicry has previously been assumed to be.

Place, publisher, year, edition, pages
Stockholm: Department of Zoology, Stockholm University, 2009. 34 p.
Müllerian mimicry, two-step evolution, gradual evolution, mutualism, predator psychology
National Category
Research subject
urn:nbn:se:su:diva-29056 (URN)978-91-7155-903-6 (ISBN)
Public defence
2009-09-25, Nordenskiöldsalen, Geovetenskapens hus, Svante Arrhenius väg 8 C, Stockholm, 10:00 (English)
At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Accepted. Available from: 2009-09-03 Created: 2009-08-10 Last updated: 2014-10-13Bibliographically approved

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Balogh, Alexandra C.V.Leimar, Olof
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