Heterozygote advantage and pleiotropy contribute to intraspecific color trait variability

Abstract

The persistence of intrapopulation phenotypic variation typically requires some form of balancing selection because drift and directional selection eventually erode genetic variation. Heterozygote advantage remains a classic explanation for the maintenance of genetic variation in the face of selection. However, examples of heterozygote advantage, other than those associated with disease resistance, are rather uncommon. Across most of its distribution, males of the aposematic moth Arctia plantaginis have two hindwing phenotypes determined by a heritable one locus‐two allele polymorphism (genotypes: WW/Wy = white morph, yy = yellow morph). Using genotyped moths, we show that the presence of one or two copies of the yellow allele affects several life‐history traits. Reproductive output of both males and females and female mating success are negatively affected by two copies of the yellow allele. Females carrying one yellow allele (i.e., Wy) have higher fertility, hatching success, and offspring survival than either homozygote, thus leading to strong heterozygote advantage. Our results indicate strong female contribution especially at the postcopulatory stage in maintaining the color polymorphism. The interplay between heterozygote advantage, yellow allele pleiotropic effect, and morph‐specific predation pressure may exert balancing selection on the color locus, suggesting that color polymorphism may be maintained through complex interactions between natural and sexual selection.

Chemical defences indicate distinct colour patterns with reduced variability in aposematic nudibranchs

“…Hebets & Papaj, 2005; Postema, Lippey, & Armstrong-Ingram, 2022). Indeed, genetic mechanisms underlying adaptive processes in defensive colouration remain largely elusive, even for individual components of colour patterns such as spot size or colour variability of a distinct pattern element (but see De Pasqual et al, 2022). Furthermore, how and if environmental factors, such as turbidity, temperature and variability in spatial and seasonal processes (e.g.…”

Host’s genetic background determines the outcome of reciprocal faecal transplantation on life-history traits and microbiome composition

“…We included four families to cover for possible variation among families in the analysis of genotype effects, and we did not analyze family effects. The general rearing protocol and the pedigree are described in detail in Nokelainen et al [ 71 ] and De Pasqual et al [ 17 ]. In the rearing protocol, larvae are fed with dandelion ( Taraxacum spp .)…”

Morph-linked variation in female pheromone signaling and male response in a polymorphic moth

“…Males of either morph have a reproductive advantage when they represent the most common morph (Gordon et al, 2015) whereas all male morphs have equal chances of mating when females are not presented with an alternative mating partner (Chargé et al, 2016;De Pasqual et al, 2022). Yellow males are generally characterized by lower reproductive success than whites (De Pasqual et al, 2022;Gordon et al, 2018) while Wy females have the highest reproductive output among female genotypes (De Pasqual et al, 2022). As a proxy for precopulatory mate searching behavior, Rojas et al, (2015) found that yellow males have a narrower daily flying activity than white males, whereas very little is known about how female behavior and attractiveness vary.…”

“…First, we tested whether females of the three color genotypes were differentially attractive to males. We hypothesized that heterozygote females with highest reproductive success are most attractive, following De Pasqual et al, (2022). Since females were indeed differentially attractive, we tested for potential signaling strategies, by investigating how long it took for the female to attract the first male and the duration of female attractiveness.…”