The evolution of sexually dimorphic cuticular hydrocarbons in blowflies (Diptera: Calliphoridae)

Abstract

Cuticular hydrocarbons (CHCs) are organic compounds found on the cuticles of all insects which can act as close-contact pheromones, while also providing a hydrophobic barrier to water loss. Given their widespread importance in sexual behaviour and survival, CHCs have likely contributed heavily to the adaptation and speciation of insects. Despite this, the patterns and mechanisms of their diversification have been studied in very few taxa. Here, we perform the first study of CHC diversification in blowflies, focussing on wild populations of the ecologically diverse genus Chrysomya. We convert CHC profiles into qualitative and quantitative traits and assess their inter-and intra-specific variation across 10 species. We also construct a global phylogeny of Chrysomya, onto which CHCs were mapped to explore the patterns of their diversification. For the first time, we demonstrate that blowflies express an exceptional diversity of CHCs, which have diversified in a nonphylogenetic and punctuated manner, are species-specific and sexually dimorphic. It is likely that both ecological and sexual selection have shaped these patterns of CHC diversification, and our study now provides a comprehensive framework for testing such hypotheses.

Love at first flight: wing interference patterns are species‐specific and sexually dimorphic in blowflies (Diptera: Calliphoridae)

“…The final figure was edited with Adobe InDesign 2019. The reduced phylogeny of the seven Australian species is based on Butterworth et al., 2020. Clade I represented by light grey branches, Clade II by dark grey branches, and Clade III by black branches…”

The blowflyChrysomya latifronsinhabits fragmented rainforests, but lacks genetic diversity and population structure

“…Following sequencing, reads were aligned to the genome of Chrysomya rufifacies Macquart 1843 (Andere et al 2020), a close genetic relative of Ch. latifrons (Butterworth et al 2020) with a sequenced genome. Genomic data were then processed using the DarTseq™ bioinformatic pipeline (Georges et al 2018), which performed filtering and variant calling, and generated final genotypes.…”

“…Blowflies (Diptera: Calliphoridae) are perfectly suited to this indicator approach because they are widespread throughout rainforests, extremely abundant, and easy to capture in the wild (Norris 1959; Badenhorst and Villet 2018; Butterworth et al 2020). Blowflies are also highly vagile (Norris 1959) and many species exhibit wide dietary breadths – opportunistically feeding on a range of resources, including vertebrate and invertebrate carrion, dung, decaying plant matter, and pollen (Dear 1985; Brodie et al 2015).…”

Cuticular Hydrocarbon Plasticity in Three Rice Planthopper Species

“…Secondly, CHCs are shaped by selection of their communication function from intraspecific and interspecific interactions [ 8 , 9 ]. Thus, CHCs provide classic examples of ‘magic’ and ‘dual’ traits that affect both ecological divergence and mating signals, and could lead to reproductive isolation and the formation of new species [ 10 , 11 ]. However, existing research has mostly been limited to ants [ 5 , 7 , 12 ], wasps and bees [ 13 , 14 , 15 ], and fruit flies and blowflies [ 11 , 16 ].…”

“…Thus, CHCs provide classic examples of ‘magic’ and ‘dual’ traits that affect both ecological divergence and mating signals, and could lead to reproductive isolation and the formation of new species [ 10 , 11 ]. However, existing research has mostly been limited to ants [ 5 , 7 , 12 ], wasps and bees [ 13 , 14 , 15 ], and fruit flies and blowflies [ 11 , 16 ]. It is evident that the CHC profiles vary greatly between different insect groups.…”