Henry Walter Bates - His Work

His Work

Henry Bates was one of a group of outstanding naturalist-explorers who were supporters of the theory of evolution by natural selection (Charles Darwin and Alfred Russel Wallace 1858). Other members of this group included J.D. Hooker, Fritz Müller, Richard Spruce and Thomas Henry Huxley.

Bates' work on Amazonian butterflies led him to develop the first scientific account of mimicry, especially the kind of mimicry which bears his name: Batesian mimicry. This is the mimicry by a palatable species of an unpalatable or noxious species. A common example seen in temperate gardens is the hover-fly, many of which – though bearing no sting – mimic the warning colouration of hymenoptera (wasps and bees). Such mimicry does not need to be perfect to improve the survival of the palatable species.

Bates noted of the Heliconids (long-wings) that they were forest-dwellers who were:

1. abundant 2. conspicuous and slow-flying. 3. gregarious; and also 4. the adults frequented flowers. 5. the larvae fed together.

And yet, said Bates "I never saw the flocks of slow-flying Heliconidae in the woods persecuted by birds or dragonflies... nor when at rest did they appear to be molested by lizards, or predacious flies of the family Asilidae which were very often seen pouncing on butterflies of other families... In contrast, the Pieridae (sulfur butterflies), to which Leptalis belongs are much persecuted."

Bates observed that a large number of the Heliconid species are accompanied in the districts they inhabit by other species (Pierids), which counterfeit them, and often cannot be distinguished from them in flight. They fly in the same parts of the forest as the model (Heliconid) and often in company with them. Local races of the model are accompanied by corresponding races or species of the mimic. So a scarce, edible species assumes the appearance of an abundant robust, noxious species. Predators learn to avoid the noxious species, and a degree of protection covers the edible species, no doubt proportional to its degree of likeness to the model. All aspects of this situation can be, and have been, the subject of research. Thus began a field of research which is still quite active today.

Bates, Wallace and Müller believed that Batesian and Müllerian mimicry provided evidence for the action of natural selection, a view which is now standard amongst biologists. Field and experimental work on these ideas continues to this day; the topic connects strongly to speciation, genetics and development.