Butterflies use differences in leaf shape to distinguish between plants

The preference of Heliconius butterflies for certain leaf shapes is innate, but can be reversed through learning. These results support a decades-old theory for explaining the evolution of the exceptional diversity of leaf shapes in passionflowers.
The tropical butterfly Heliconius eratodistinguishes between shapes, and uses them as a cue for choosing the plants on which to feed and lay eggs, shows new research by scientists from the University of Cambridge and the Smithsonian Tropical Research Institute. The butterfly has an innate preference for passionflowers with particular leaf shapes, but can learn to overcome this preference in favor of other shapes, especially those that are the most abundant in the local flora. These preferences can promote the evolution of plant biodiversity.

Heliconius erato, the red passionflower butterfly, is a large (5 to 8 cm wingspan), white-red-black butterfly that occurs throughout Central America and tropical South America. Females lay their eggs on passionflowers (Passiflora), a genus of tropical vines with extreme variation in leaf shape, both between and within species. For example, related species can have triangular, elongated, elliptic, lobed, or spear-shaped leaves, while even on the same plant leaf shape may vary between young and old, or sun-exposed or overshadowed leaves. Once caterpillars hatch from the eggs, they start feeding on the leaves and shoots of the host plant, often causing considerable damage.