Evolution of aquatic snails' defences resulted in clade-specific differences in egg toxicity, pigments, and warning colouration

Oviparous animals have evolved diverse strategies that deter egg predation. In terrestrial species, these often include noxious compounds and aposematic signalling, but little is known in freshwater environments. Here we unravel the evolutionary and ecological strategies of Pomacea, aquatic snails that lay conspicuous masses of toxic orange-pink eggs to reduce predation risk. We reveal the interplay among warning colouration, toxicity, and predator visual perception that enables the evolution of advanced chemical defences. We provide evidence that snails modify dietary carotenoids and that this controls egg colouration in a clade-specific manner. Snails from the canaliculata clade accumulate more and brighter-coloured egg carotenoid pigments than those from the bridgesii clade. The conspicuousness of colour signals was assessed using field data, spectral reflectance measurements, and visual modelling. We show that aposematic signal variation among species is likely noticeable to putati..., , # Evolution of aquatic snails' defences resulted in clade-specific differences in egg toxicity, pigments, and warning colouration.

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Raw data is on file (**PomaceaHH_3.csv**).

## Descriptions

### **PomaceaHH_3.csv**

This matrix contains the spectral data from the egg clutches of three Pomacea snail species plus two backgrounds on which the eggs are laid:

* wavelength
*nm*: Wavelength in nanometers
* Pomacea samples include P. maculata, P. diffusa, P. scalaris, P. canaliculata; background samples include leaf of Sagitaria montevidensis and rock substrate.
*species* the first three letters of the column name code the species name epithet
*sample* the first nine letters code the unique sample name
*replicate* the 11th letter codes the replicate of each sample
* Background spectra are coded with the first three letter of the column name as:
*bkg* with \"bkgsaeta\" and \"bkgtosca\" indicating Sagitaria or rock substrates, respectively

## Code/Software

R is required to run *p...,