Hybrid effects in field populations of the African monarch butterfly, Danaus chrysippus (L.) (Lepidoptera: Nymphalidae)

Abstract

Heterosis, Haldane and Bateson-Dobzhansky-Muller effects have been widely documented amongst a range of plants and animals. However, typically these effects are shown by taking parents of known genotype into the laboratory and measuring components of the F1 progeny under laboratory conditions. This leaves in doubt the real significance of such effects in the field. Here we use the well-known colour pattern genotypes of the African monarch or queen (Danaus chrysippus), which also control wing length, to test these effects both in the laboratory and in a contact zone in the field. By measuring the wing lengths in animals of known colour pattern genotype we show clear evidence for all three hybrid effects at the A and BC colour patterning loci, and importantly, that these same effects persist in the same presumptive F1s when measured in hybrid populations in the field. This demonstrates the power of a system in which genotypes can be directly inferred in the field and highlights that all three hybrid effects can be seen in the East African contact zone of this fascinating butterfly.

Penetrance interactions of colour pattern loci in the African Monarch and their implications for the evolution of dominance

“…( 2022 ). We view this recent meeting of the different morphs as an example of admixture polymorphism (Smith et al., 2021 ; Wall, 2000 ), as the morphs can readily interbreed, and the corresponding heterozygotes are therefore common across the contact zone (Smith et al., 1997 ). The African Monarch therefore differs from other classic examples of colour polymorphism in that colour pattern alleles in the corresponding heterozygotes meet transiently and their expected fitness in the face of predation remains unclear.…”