Seasonal phenotypic plasticity of wing melanisation in the cabbage white butterfly, Pieris rapae L. (Lepidoptera: Pieridae)

Abstract

1. Effective thermoregulation is crucial for the fitness of small flying in sects. Phenotypic plasticity of the ventral hindwing of pierid butterflies is widely recognised as adaptive for effective thermoregulation. Butterflies eclosing in cooler environments have more heavily melanised wings that absorb solar radiation, thus allowing flight under these cool conditions.2. Many pierids also exhibit phenotypic plasticity of dorsal forewing melanisation but in this case, cooler environments reduce melanisation. It has been hypothesised that this plasticity is also adaptive because it increases solar reflection from the wing surfaces onto the body in certain basking postures.3. The degree of seasonal variation in ventral hindwing and dorsal forewing melanisation of wild-caught Pieris rapae was quantified to determine if it shows patterns of plasticity similar to that documented for other Pieris species.4. Male wing melanisation on both wing surfaces shows the characteristic seasonal, adaptive plasticity. However, only some dorsal forewing pattern elements of females conformed to the predictions of the hypothesis of adaptive dorsal forewing melanisation. Sexual dimorphism of wing pattern plasticity may result from, and/or affect, sexual dimorphism of behaviour and physiology of these butterflies.

Exploring plastic and genetic responses to temperature variation using copper butterflies

“…facilitating flight at suboptimal temperatures, are well established (e.g. Ellers & Boggs 2004, Stoehr & Goux 2008. More interestingly though, we found a parallel pattern in pupal melanisation, showing a strong increase with increasing altitude, in L. hippothoe and L. tityrus (Karl et al 2009c).…”

Historical changes in thermoregulatory traits of alpine butterflies reveal complex ecological and evolutionary responses to recent climate change

“…However, whether wing coloration has any thermoregulatory significance was unclear for most species in the analysis [55,56]. Although increasing melanism in response to decreasing developmental temperatures has been widely reported in insects, this includes many cases in which melanism plays no role in thermoregulation [57][58][59][60]. Our findings correspond to those of J Stamberger [34] who documented decreases in wing melanism and setal length in C. meadii with warmer temperatures, but no trend across years, for a more restricted time period and set of sites in Colorado.…”

Responses of disparate phenotypically-plastic, melanin-based traits to common cues: limits to the benefits of adaptive plasticity?

“…I chose these treatments because previous work established that they induce wing melanization plasticity in a related butterfly, Pieris occidentalis Rearkirk (Kingsolver and Wiernasz 1991), and because other on-going experiments, unrelated to those described here, were designed to compare with those of Kingsolver and Wiernasz (1991). These treatments result in wing melanization phenotypes that are visually indistinguishable from wild-caught spring and summer animals, respectively (Stoehr and Goux 2008).…”

“…In Pieris butterflies, variation in wing melanization is a result of variation in the relative size of these wing pattern elements. Plasticity in wing melanization (''seasonal polyphenism'') in pierid butterflies is induced in response to photoperiod and/or temperature and is adaptive with respect to thermoregulation (Shapiro 1976;Kingsolver 1995a, b;Stoehr and Goux 2008). Finally, pupal color varies as well, from pale green to heavily melanized, in response to background coloration-likely an adaptation for crypsis (Poulton 1890;Smith 1980).…”