Evolution of Sexual Dimorphism in the Lepidoptera

Abstract

Among the animals, the Lepidoptera (moths and butterflies) are second only to beetles in number of described species and are known for their striking intra- and interspecific diversity. Within species, sexual dimorphism is a source of variation in life history (e.g., sexual size dimorphism and protandry), morphology (e.g., wing shape and color pattern), and behavior (e.g., chemical and visual signaling). Sexual selection and mating systems have been considered the primary forces driving the evolution of sexual dimorphism in the Lepidoptera, and alternative hypotheses have been neglected. Here, we examine opportunities for sexual selection, natural selection, and the interplay between the two forces in the evolution of sexual differences in the moths and butterflies. Our primary goal is to identify mechanisms that either facilitate or constrain the evolution of sexual dimorphism, rather than to resolve any perceived controversy between hypotheses that may not be mutually exclusive.

Small-scale variation in sexual size dimorphism and sex ratio in the aquatic mothAcentria ephemerellaDenis and Schiffermüller, 1775 (Lepidoptera: Crambidae)

“…Protandry is a common phenomenon in many moths and butterflies and can be achieved either by a shorter development time of males or a higher growth rate of males compared with females (Wiklund, Nylin, and Forsberg 1991;Zijlstra, Kesbeke, Zwaan, and Brakefield 2002;Allen et al 2011). Faster development and earlier pupation of males should lead to male-biased pupal sex ratios shortly after male larvae start to pupate.…”

“…The ultimate and proximate causes of SSD variability have been studied intensively in the last decade Tammaru et al 2010). The SSD shows strong inter-and intra-specific variability largely reflecting different reproductive adaptations of the sexes (Abouheif and Fairbairn 1997;Blanckenhorn et al 2007;Allen, Zwaan, and Brakefield 2011). The degree and direction of SSD is often caused by sex-specific sensitivity to environmental conditions (Teder and Tammaru 2005;Cox and Calsbeek 2010;.…”

“…Variability in SSD and size at metamorphosis influences the fecundity and reproductive output of many arthropod taxa Allen et al 2011). Fecundity selection on females and sexual selection on males favour larger body sizes .…”

Sexual Dimorphism Using Geometric Morphometric Approach

“…Sexual selection and mating systems have been considered the primary forces driving the evolution of sexual dimorphism in insects especially in lepidoptera, and alternative hypotheses have been neglected [56]. Recent analyses demonstrate that many lepidopteran species exhibit female-biased sexual size dimorphism 73% of 48 species in Reference [57].…”

Environmental and hormonal factors controlling reversible colour change in crab spiders

“…For instance, cryptic colouration allows some animals to escape predators by matching their background (Endler, 2006). Other animals use pigmentation for sexual display (Allen et al, 2011;Badyaev and Hill, 2003;KodricBrown, 1998) or social communication (Rohwer, 1975;Tibbetts and Dale, 2004). In some animals, conspicuous colouration through aposematism has evolved to act as a warning signal and advertise defences to predators (Stevens and Ruxton, 2012).…”