Mimicry genes reduce pre‐adult survival rate in Papilio polytes: A possible new mechanism for maintaining female‐limited polymorphism in Batesian mimicry

Abstract

Intraspecific polymorphism is widespread in insects, and its maintenance mechanism is an issue of fundamental importance in evolutionary biology. Batesian mimicry, in which palatable species gain protection from predators due to their resemblance to aposematic unpalatable or dangerous species (hereafter, model species), is regarded as a classic example of evidence of adaptation by natural selection (Bates, 1862; Ruxton, Sherratt, & Speed, 2004).

Phenotypic Plasticity of the Mimetic Swallowtail Butterfly Papilio polytes: Color Pattern Modifications and Their Implications in Mimicry Evolution

“…Females are often under higher predation pressure than males due to their higher nutritious quality of eggs in the abdomen [ 44 , 45 ]. The mimetic form has some disadvantages; it is less active [ 47 , 48 ] and has shorter life expectancy [ 49 ]. The mimetic forms are not always effective; their effectiveness depends on the number of sympatric individuals of the model species [ 69 , 70 , 71 , 72 , 73 , 74 ].…”

“…The female-limited mimicry not only in P. polytes but also in many butterflies has been explained by the high cost of expressing mimetic color patterns that can compensate for predation, which is not affordable for males [ 44 , 45 , 46 , 47 , 48 , 49 ]. While this line of explanation is reasonable, it does not take phenotypic plasticity into account.…”

Population genetic structure and evolution of Batesian mimicry in Papilio polytes from the Ryukyu Islands, Japan, analyzed by genotyping‐by‐sequencing

“…This would also enable us to address the evolution of the responsible gene, dsx, of polymorphic Batesian mimicry in Papilio butterflies (Iijima et al, 2018(Iijima et al, , 2019Komata et al, 2016;Kunte et al, 2014;Nishikawa et al, 2015;Palmer & Kronforst, 2020;Zhang et al, 2017), which should be the focus of further investigation. This dsx gene may not only control the mimetic forms, but also have pleiotropic, slightly deleterious epistatic effects potentially related to the "cost of mimics" (Katoh et al, 2020). Unveiling the molecular evolutionary dynamics of the dsx across the Ryukyu Islands in association with the NFDS for mimetic types is necessary to understand the establishment of P. polytes mimicry interacting with ecological factors.…”

“…As an alternative hypothesis, polymorphic Batesian mimicry may be explained by sexual selection and ecological–physiological trade‐offs (Burns, 1966; Cook et al., 1994; Katoh et al., 2020; Ohsaki, 2005; Vane‐Wright, 1984), or neutral evolutionary processes such as isolation by distance and phylogenetic constraint. In the simple neutral process, the mimetic and nonmimetic phenotypes have similar fitness independent of their frequencies.…”

Evolutionary origins of sexual dimorphism : Lessons from female-limited mimicry in butterflies.

“…Phylogenetic analyses show that FLM derived from sexually monomorphic non-mimetic ancestors [Kunte, 2009, Timmermans et al, 2017 suggesting that mimicry in FLM species is associated with a costly displacement from an ancestral non-mimetic phenotype. In the female-limited polymorphic butterfly Papilio polytes, where both mimetic and non-mimetic females co-exist, the mimetic allele reduces the pre-adult survival rate [Komata et al, 2020, Katoh et al, 2020 (but see [Komata et al, 2018] in the FLM butterfly Papilio memnon), highlighting cost associated with mimicry. Such trade-off between developmental constraints favouring the ancestral trait and selection promoting mimicry might differ between sexes: if predation is lower in males, the constraints limiting mimicry may overcome the benefit from mimicry in males, whereas in females the higher predation pressure may promote mimicry.…”