Heliconius species, and H. melpomene is usually less abundant than other species. Origins A recent study, using amplified fragment length polymorphism (AFLP) and mitochondrial DNA datasets, places the origin of H. melpomene to 2.1 million years ago. H. melpomene shows clustering of AFLPs by geography suggesting that the species originated in eastern South America. Food resources Caterpillars Caterpillars of Heliconius exhibit a behavior known as monophagy, meaning they feed on only one kind of plant, specifically the genus Passiflora. In H. melpomene, the host plants are limited to Passiflora oerstedii and Passiflora menispermifolia. Species of the genus Passiflora have evolved many chemical defenses, but Heliconius caterpillars have developed adaptations that allow them to continue to feed on the plants and actually incorporate the toxic compounds into their systems and make them unpalatable to predators. These interactions make Heliconius and Passiflora a model system for studies of coevolution. Adults Diet Unlike most other butterflies, several Heliconius species have been observed eating pollen as well as nectar. The exact mechanism by which the butterfly digests the pollen is uncertain; it was originally thought that once the pollen was soaked in nectar after ingestion, it would then be able to be digested by the butterfly. Recently, however, the enzyme protease was discovered in the butterfly's saliva, which implies an adaptation for breaking down pollen. This enzyme was found in higher concentrations in the saliva of female butterflies, likely due to the greater need of nutrition associated with reproduction. These adaptations allow the butterflies to extract important amino acids from the pollen, which, in addition to general nutrition benefits, allows H. melpomene to have brighter colors and be more distasteful to predators than their non-pollen-foraging counterparts. It is thought that this foraging adaptation and subsequent enhancement of coloration contributed to the speciation of Heliconius. Pollination Pollen is a rarely utilized but efficient protein source for Lepidoptera species. While foraging for pollen, adults accumulate pollen on the end of their proboscis and the grains stay there for long periods of time. These pollen grains are transferred to the stamen of another plant the butterfly visits while foraging. While there are many plants in H. melpomene range that provide suitable nutrients, only a few of these are visited by the butterfly. This makes the butterfly an efficient pollinator for the flowers it visits as there is a low likelihood of a plant receiving the wrong kind