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.
Egg phenotypes
These data were collected from a laboratory experiment. Abbreviations used for column headings are described below. MotherID - a distinct code for the female that laid the clutch described; Mothersize - pronotum width; labtime - the number of days the particular female spent in the lab before her clutch was collected; FatherID - a distinct code for the male mated to the female that laid the clutch described; Eggsaturation - (r) calculated as the shortest (Euclidian) distance from the achromatic origin, where saturation increases the further a point is from the origin; Eggbrightness - overall reflectance across the spectrum, and calculated independently of colour by applying the formula: (LW+MW+SW+UV)/4; Egghue1 - (LW+MW) / (SW+UV); Egghue2 - (LW+UV) / (SW+MW); Eggcoc - concentration of coccinelline in the eggs; Eggprecoc - concentration of precoccinelline in the eggs; Eggcarotenoids - concentration of carotetenoids in the eggs
egg.txt
Offspring phenotypes
These data were collected from a laboratory experiment. Abbreviations used for column headings are described below. OffspringID - a distinct code for the individual offspring with the phenotype described; MotherID - a distinct code for the mother of the offspring described; FatherID - a distinct code for the male mated to the mother of the offspring described; Eggsaturation - (r) calculated as the shortest (Euclidian) distance from the achromatic origin, where saturation increases the further a point is from the origin; Eggbrightness - overall reflectance across the spectrum, and calculated independently of colour by applying the formula: (LW+MW+SW+UV)/4; Egghue1 - (LW+MW) / (SW+UV); Egghue2 - (LW+UV) / (SW+MW); Eggcoc - concentration of coccinelline in the eggs; Eggprecoc - concentration of precoccinelline in the eggs; Eggcarotenoids - concentration of carotetenoids in the eggs; hatchsuccess - hatched larvae / total eggs; Sex - male or female; Offspringgrowthrate - calculated as the regression coefficient of an exponential curve fitted to the x(age in days at the start of each instar stage) and y(body mass) for each larva; Offspringmass - weighed to the nearest 0.1µg upon eclosion; Offspringdevtime - total number of days between hatching and eclosion as adults; Offspringsat - (r) calculated as the shortest (Euclidian) distance from the achromatic origin, where saturation increases the further a point is from the origin; OffspringBrightness - overall reflectance across the spectrum, and calculated independently of colour by applying the formula: (LW+MW+SW+UV)/4; Offspringhue1 - (LW+MW) / (SW+UV); Offspringhue2 - (LW+UV) / (SW+MW); Offspringcoc - concentration of coccinelline in the individual; Offspringprecoc - concentration of precoccinelline in the individual
offspring.txt
Survival
These data were collected from a laboratory experiment. Abbreviations used for column headings are described below. LarvaeID - a distinct code for the individual described; MotherID - a distinct code for the female that laid the clutch described; FatherID - a distinct code for the male mated to the female that laid the clutch described; Eggcarotenoids - concentration of carotetenoids in the eggs; Survival - whether the individual survived to adulthood.
survival.txt
