Shape is generally important in biology, often providing variability for selection to take place and therefore shape analysis is utilized in taxonomic classification. However, shape has been widely disregarded when studying signalling, with focus being on salience, colour and size. When studying aposematism, up until recently, the social interaction of the prey species was also neglected, with focus on the social environment of the predator being the factor applying pressure to the selection of the prey species. This study uses geometric morphometrics to analyse the shape of the warning signal in the burying beetle (Nicrophorus vespilloides) which exhibits two sets of orange stripes across its elytra, displaying the degree of their distastefulness to predators – known as aposematism. Variation was found in the shape of the stripes when modelled cumulatively and separately. In some cases, this variation correlated to the amount of defensive fluid they produced when agitated. This was further affected by whether the individual beetles received reduced care or full care until they dispersed for pupation, and surprisingly, in one case was also affected by sex. These findings have highlighted the need for further research into shape and the social impacts upon it with regards to interspecific relationships. This study also draws attention to the fact that the aposematic signal exhibits a degree of sexual dimorphism.
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