^^ AND -^^^^ 



JOURNAL OF VARIATION. 



Vol. X. No. 5. May Ioth, 1898. 



Theories of Mimicry, as illustrated by African Butterflies.* 



By Piofesso*.- EDWAKD B. POULTON, M.A., F.fi.S., etc. 



H. W. Bates, in his epoch-making paper {Tram. Linn. Snc. Land., 

 vol. xxiii., 18G2), first gave an intelligible theory of mimicry, and ac- 

 counted for the superficial resemblances which had been known for so 

 long by supposing that the most dominant, well-defended, and con- 

 spicuous forms in a country become the models towards which natural 

 selection leads many of the weaker hard-pressed species in the same 

 locality. The material on which Bates' theory was formed was confined 

 to tropical America, and his generalisation remained incomplete until it 

 could be applied to the other great tropical regions. This want, how- 

 ever, was soon supplied by A. R. Wallace for the East {Trans. Linn. 

 Soc. Lond., vol. XXV., 1866), and by Roland Trimen for Africa {Trans. 

 Linn. Soc. Land., vol. xxvi., 1870). 



In Bates' original paper a certain class of facts — frequently men- 

 tioned and abundantly illustrated — cannot be explained uncler his 

 theory of mimicry. This is the strong resemblance which is apt to 

 exist between the dominant forms themselves, and which is as minute 

 and as remarkable as the resemblance of the weaker for the stronger 

 species. Bates pointed out that this was unsolved by his theory, and 

 both he and Wallace were compelled to suggest the direct action of 

 some unknown local influence as the possible cause. There the matter 

 rested until Fritz Miiller, in a paper published in Kosmos for May, 

 1879, suggested an explanation, viz., that the dominant forms gain an 

 advantage by this resemblance, inasmuch as it facilitates the educa- 

 tion of their enemies by giving them fewer patterns to learn. The 

 necessary waste of life by which the education of young birds, etc., is 

 brought about, is here divided between the various species of a closely 

 convergent group, instead of being contributed by each member inde- 

 pendently. The chief sub-families of butterflies which in tropical 

 America appear to be specially distasteful to insect-eating animals, and 

 which are specially mimicked by others, are the Ihvnainae, Jthoniiinac, 

 J Liifdnindi', ixnd Acraeinac. Of . these the second and third are con- 

 fined to this part of the world. The resemblances which Fritz 

 Miiller explained are those which occur very connnonly between the 

 l>anainac, Ithomiinai', ILdiaminac, and loss commonly the Acraeinae 



• Abstract of a Paper read before Section D of the British Association at 

 Toronto on Friday, Aiif^nist "iOtli, is'.j?. Beprintcd by permission of the Coraraittee 

 of tiae British Association. 



