Müllerian mimicry: an examination of Fisher's theory of gradual evolutionary change

Abstract

In 1927, Fisher suggested that Mü llerian mimicry evolution could be gradual and driven by predator generalization. A competing possibility is the so-called two-step hypothesis, entailing that Mü llerian 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, it has fewer problems with purifying selection. We also examined the 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.

Predator dependent mimetic complexes: Do passerine birds avoid Central European red-and-black Heteroptera?

“…Balogh & Leimar, 2005;Ruxton et al, 2008). Our results suggest that considerable differences may exist even among wild-caught and potentially experienced birds in their reactions to individual prey species within an apparent mimetic complex as seen by human eyes.…”

“…There are many theoretical studies and mathematical models focused on mimicry (Speed, 1993(Speed, , 1999Balogh & Leimar, 2005;Balogh et al, 2008;Ruxton et al, 2008;Sherratt, 2008) but only few experimental studies. Most of the experiments were carried out using artificial prey and a single predator species (e.g., Rowe et al, 2004;Ihalainen et al, 2007).…”

Prey community structure affects how predators select for Müllerian mimicry

“…Despite theoretical [2][3][4][5][6], genetic [7,8], phylogenetic [9][10][11] and experimental studies [12 -17] of Mü llerian mimicry, the general conditions that select for it remain unclear. Specifically, there is continuing discussion about the importance of naive versus experienced predators [16 -19], and the importance of prey community structure in selection for mimicry [2,3,20 -22].…”

“…Whether warning signal similarity is acquired gradually or in two distinctive phases is an open empirical question, but both scenarios assume that signal similarity starts as crude resemblance (or no resemblance) that is further refined [4][5][6]23,24]. Because predators should generalize widely between defended prey [14,25,26], it is unclear what conditions select for precise resemblance (especially if there are costs of mimicry [24]); consequently, it is unclear why Mü llerian co-mimics in nature can resemble each other with astonishing accuracy [12,27].…”

Mendelian-Mutationism: The Forgotten Evolutionary Synthesis

“…The early geneticists' skepticism in regard to smooth change based on continuous variation, almost universally misconstrued, was 6 Punnett's stature is indicated by (1) his debate with Poulton over the evolution of mimicry, culminating in an early book (Punnett, 1915) targeted for criticism by Fisher, and still cited by scientists (e.g., Balogh and Leimar, 2005) as a historic touchstone, and (2) direct historic references such as Wallace's (1909) personal criticism of ''Bateson, Punnett, de Vries and Company'' as ''the self-deluded specialists'' of the new view, and Reid's (1913) Buttolph's (2008) study as early geneticists, active in the first decade of the twentieth century. Johannsen's experimental results were profoundly influential, but the direct influence of Johannsen's evolutionary thinking was, we suspect, less than that of Punnett.…”