Data from: Maternal effects and warning signal honesty in eggs and offspring of an aposematic ladybird beetle
Winters, Anne E. et al. (2015), Data from: Maternal effects and warning signal honesty in eggs and offspring of an aposematic ladybird beetle, Dryad, Dataset, https://doi.org/10.5061/dryad.5v42p
1. The eggs of oviparous species are often subject to intense predation pressure. One parental strategy to deter predators is to produce eggs that are laced with noxious chemicals and are conspicuously coloured (i.e. aposematism). 2. Ladybird eggs are conspicuously coloured and contain alkaloids; these traits are believed to function in concert as visual signal and chemical defence, respectively, to deter predators. However, it remains unclear whether such aposematic signals reveal the strength (rather than simply the existence) of chemical defences. 3. Furthermore, additional functions of egg pigments and toxins could apply; in particular mothers might deposit such resources into eggs to aid the development of offspring, or to provide resources that could contribute to aposematic traits in offspring. 4. We bred wild-caught seven-spot ladybird beetles (Coccinella septempunctata) in the laboratory, and then measured relationships between egg colouration and toxin concentrations (i.e. the alkaloids precoccinelline and coccinelline). We also measured relationships between egg carotenoids and egg colouration, and between egg colouration and toxin levels, and the elytra colouration and toxin concentrations of offspring at eclosion for a subset of eggs that were allowed to develop. 5. Egg carotenoids predicted egg colour saturation. In turn egg colour saturation and hue positively predicted egg concentrations of precoccinelline. However, there were no significant relationships between egg coccinelline concentration and any measure of egg colouration. 6. In recently eclosed adults of both sexes elytra saturation was significantly explained by variation in egg saturation and hue. Finally, body concentrations of coccinelline were significantly explained by variation in elytra hue. 7. These results suggest that the colouration of C. septempunctata eggs is a reliable signal of the strength of chemical defences contained therein, but in addition, maternal investment of pigments and toxins into eggs may serve to influence the reliability of aposematic signalling in resultant offspring.