named after the American ecologist . Gilbertian mimicry occurs in the genus Passiflora. The leaves of this plant contain toxins that deter herbivorous animals. However, some Heliconius butterfly larvae have evolved enzymes that break down these toxins, allowing them to specialize on this genus. This has created further selection pressure on the host plants, which have evolved stipules that mimic mature Heliconius eggs near the point of hatching. These butterflies tend to avoid laying eggs near existing ones, which helps avoid exploitative intraspecific competition between caterpillars — those that lay on vacant leaves provide their offspring with a greater chance of survival. Most Heliconius larvae are cannibalistic, meaning that on leaves older eggs hatch first and eat the new arrivals. Thus, it seems that such plants have evolved egg dummies under selection pressure from these grazing herbivore enemies. In addition, the decoy eggs are also nectaries, attracting predators of the caterpillars such as ants and wasps as a further defence. Browerian Browerian mimicry, named after Lincoln P. Brower and Jane Van Zandt Brower, is a postulated form of automimicry; where the model belongs to the same species as the mimic. This is the analogue of Batesian mimicry within a single species, and occurs when there is a palatability spectrum within a population. Examples include the monarch and the queen from the subfamily Danainae, which feed on milkweed species of varying toxicity. These species store toxins from its host plant, which are maintained even in the adult (imago) form. As levels of toxin vary depending on diet during the larval stage, some individuals are more toxic than others. Less palatable organisms, therefore, mimic more dangerous individuals, with their likeness already perfected. This is not always the case, however. In sexually dimorphic species, one sex may be more of a threat than the other, which could mimic the protected sex. Evidence for this possibility is provided by the behaviour of a monkey from Gabon, which regularly ate male moths of the genus Anaphe, but promptly stopped after it tasted a noxious female. Aggressive Predators Aggressive mimicry is found in predators or parasites that share some of the characteristics of a harmless species, allowing them to avoid detection by their prey or host; this can be compared with the story of the wolf in sheep's clothing as long as it is understood that no conscious deceptive intent is involved. The mimic may resemble