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

Batesian mimicry, in which harmless organisms resemble unpalatable or harmful species, is a well-studied adaptation for predation avoidance. The females of some Batesian mimic species comprise mimetic and non-mimetic individuals. Mimetic females of such polymorphic species clearly have a selective advantage due to decreased predation pressure, but the selective forces that maintain non-mimetic females in a population remain unclear. In the swallowtail butterfly, Papilio polytes, female polymorphism is controlled by the H (non-mimetic) and h (mimetic) alleles at a single autosomal locus. Here, we examined if the dominant H allele has a deleterious effect on the pre-adult survival rate (egg-to-adult emergence rate). We repeated an assortative mating-like treatment—i.e. breeding of males and females whose mothers had the same phenotype (mimetic or non-mimetic)—for three consecutive generations, while avoiding inbreeding. Results showed that pre-adult survival rate decreased over generation...