page_title: The Colours of Animals
section_title: Approach
hierarchical_section_title: The Colours of Animals / Book / Approach
caption_attribution_description: English: Title page of first edition of The Colours of Animals, their meaning and use, especially considered in the case of insects by Edward Bagnall Poulton, MA, FRS, etc, published by Kegan Paul, Trench, Trübner, &amp; Co, 1890
context_page_description: The Colours of Animals is a zoology book written in 1890 by Sir Edward Bagnall Poulton. It was the first substantial textbook to argue the case for Darwinian selection applying to all aspects of animal coloration. The book also pioneered the concept of frequency-dependent selection and introduced the term "aposematism".
  The book begins with a brief account of the physical causes of animal coloration. The second chapter gives an overview of the book, describing the various uses of colour in terms of the advantages it can bring through natural selection. The next seven chapters describe camouflage, both in predators and in prey. Methods of camouflage covered include background matching, resemblance to specific objects such as bird droppings, self-decoration with materials from the environment, and the seasonal colour change of arctic animals. Two chapters cover warning colours, including both Batesian mimicry, where the mimic is edible, and Mullerian mimicry, where distasteful species mimic each other. A chapter then looks at how animals combine multiple methods of defence, for instance in the puss moth. Two chapters examine coloration related to sexual selection.
context_section_description: Evidence for natural selection
  Poulton explains in his Preface that
  My chief object has been to demonstrate the utility of colour and marking in animals. In many cases I have attempted to prove that Natural Selection has sufficed to account for the results achieved; and I fully believe that further knowledge will prove that this principle explains the origin of all appearances except those which are due to the subordinate principle of Sexual Selection...
  — E.B. Poulton
  Evidence for sexual selection
  Poulton strongly supports Darwin both on the general theme of natural selection, and on the power of sexual selection in species which are sexually dimorphic (where, usually, the male is showier than the female):
  When we look at the marvellous eyes upon the train of a Peacock, or the more beautiful markings on the feathers of the  male Argus Pheasant, it seems impossible that so wonderful and complete a result can have been produced by the aesthetic preferences of female birds. And yet Mr. Darwin shows the relation between these characters and much simpler markings on other parts of the surface. He proves that the one has been derived from the other by gradual modification... Such facts, while eminently suggestive of ... some selective agency, seem to be unexplained by any other theory.
  — E.B. Poulton
  Poulton knew his view was controversial, but believed he was winning the argument:
  Mr. Wallace's chief objection is the lack of evidence that the female has any aesthetic preferences at all in the selection of her mate. When, however, he admits that display of their decorative plumage by male birds is 'demonstrated', and that the females are in all probability 'pleased or excited by the display', he certainly admits the possession of an aesthetic sense...
  — E.B. Poulton
  Frequency-dependent selection
  In The Colours of Animals, Poulton introduced the concept of frequency-dependent selection (selection based on how abundant a form is) in the context of a polymorphism which he argued would otherwise soon vanish:
  If we breed from moths developed from the green larvae of, e.g., the Large Emerald, the larvae in the next generation are chiefly green, and after several generations there is little doubt that the brown form would become excessively rare; so also the green form would disappear if we bred from the brown varieties. But in nature both forms are common, and therefore it is certain that both must be advantageous to the species, or one of them would quickly disappear. I believe that it is a benefit to the species that some of its larvae should resemble brown and others green catkins, instead of all of them resembling either brown or green. In the former case the foes have a wider range of objects for which they may mistake the larvae, and the search must occupy more time, for equivalent results, than in the case of other species which are not dimorphic.
  — E.B. Poulton
  Mimicry and aposematism
  The basic concept of warning coloration (aposematism, like the black and yellow pattern of a wasp) is approached very simply:
  When an animal possesses an unpleasant attribute, it is often to its advantage to advertise the fact as publicly as possible. In this way it escapes a great deal of experimental 'tasting.' The conspicuous patterns and strongly contrasted colours which serve as the signal of danger or inedibility are known as Warning Colours.
  — E.B. Poulton
  In the next paragraph Poulton ties aposematism to mimicry as follows:
  It is these Warning Colours which are nearly always the objects of Protective Mimicry, and it will therefore be convenient to describe the former before the latter.
  — E.B. Poulton
  Poulton introduced the term aposematism with the words:
  The second head (Sematic Colours) includes Warning Colours and Recognition Markings: the former warn an enemy off, and are therefore called Aposematic;
  — E.B. Poulton
caption: Title page of first edition of The Colours of Animals, 1890
exif: {}