Heliconiine butterflies are bright colored to advertise to predators about their toxicity – they have cyanide-containing compounds called cyanogenic glucosides. These butterflies can both de novo biosynthesize their toxins or sequester them from their obligatory larval hostplant (Passifloraceae) (de Castro et al. 2017). There is a balance between biosynthesis and sequestration in heliconiines (de Castro et al. 2018, Sculfort et al. 2020).
Phenotypical plasticity in toxicity – Heliconius reduce biosynthesis when toxins that can be sequestered are available in the hostplant and increase biosynthesis when sequestration is not possible (de Castro et al. 2021). This phenotypical plasticity allows them to maintain their toxicity regardless of the chemical profile of their hostplants. Biochemical plasticity has fitness costs for species/populations specialized in sequestration.
The genetic basis of toxicity – We have used CRISPR-Cas and 58 new heliconiine genomes (Cicconardi et al, 2023) to investigate the evolutionary history of toxin biosynthesis in the Heliconiine tribe (de Castro et al. – in prep). We are also doing transcriptomic analyses to identify the genes responsible for biochemical plasticity in Heliconius.
Life-history evolution – The toxicity of the butterflies is not only affected by their larval hostplant, but also their adult diet (de Castro et al. 2023). Different of other nectivorous butterflies, Heliconius also feed on pollen. There is a age- and sex- specific affect of pollen deprivation on butterfly body weight, toxicity and fertility: only mature females are affected!
References
Érika de Castro, Josie McPherson, Glennis Jullian, Anniina Mattila, Søren Bak, Stephen Montgomery & Chris Jiggins (2023). Pollen-feeding delay reproductive senescence and maintains toxicity in Heliconius butterflies. BioRxix recommended by PCI Evo Bio.
Francesco Cicconardi, Edoardo Milanetti, Érika de Castro, … & Stephen Montgomery (2023). Evolutionary dynamics of genome size and content during the adaptive radiation of Heliconiini butterflies. Nature Communications 14 (1) 5620.
Érika de Castro, Jamie Musgrove, Søren Bak, W. Owen McMillan & Chris Jiggins (2021). Phenotypic plasticity in chemical defence of butterflies allows usage of diverse host plants. Biology letters, 17 (3), 20200863.
Érika de Castro. Rojan Demirtas, Anna F. Orteu, Carl Erik Olsen, Saddik Motawie, Márcio Cardoso, Mika Zagrobelny & Søren Bak. (2019). The dynamics of cyanide defences in the life cycle of an aposematic butterfly: Biosynthesis versus sequestration. Insect biochemistry and molecular biology, 116, 103259.
Ombeline Sculfort, Érika de Castro, Krystof M. Kozak, K. M., Søren Bak., Marianne Elias, Bastien Nay & Violaine Llaurens. (2020). Variation of chemical compounds in wild Heliconiini reveals ecological factors involved in the evolution of chemical defenses in mimetic butterflies. Ecology and evolution, 10(5), 2677-2694.
Érika de Castro, Mika Zagrobelny, Márcio Cardoso, Juan Pablo Zurano, René Feyereisen and Søren Bak (2018). Sequestration and biosynthesis of cyanogenic glucosides in passion vine butterflies and consequences for the diversification of their host plants. Ecology & Evolution 00:1-14, 201
Érika de Castro, Mika Zagrobelny, Márcio Cadoso & Søren Bak (2017) . The arms race between passion vines and heliconiines butterflies – new insights in an ancient subject. Biological Reviews 93:555-573