Major Patterns of Variation | 273 



competition of overspecialized types only serves to illustrate the 

 difficulties in dealing with ecological situations of this sort. 



Many major discontinuities observable today seem to have had 

 their origin before the start of a satisfactory fossil record. Even where 

 a good fossil record of intermediate types exists, however, one can- 

 not be sure of the exact causes of the present gaps. The commonly 

 stated hypothesis that bird competition accounts for the absence of 

 Archacoptcnjx-Uke organisms in the recent fauna may be entirely 

 incorrect. Perhaps these early types specialized in feeding on an 

 organism that became extinct for climatic reasons. One might, of 

 course, construct a large number of hypotheses, most of which have 

 about equal probability of being incorrect. 



Fig. 1 1.9 I Convergence presumably due to mimicry. Upper row: left, 

 the moth Alcidis agatht/rsus; riglit, the motli Cijdosia hcstinioidcs. Lower 

 row: left, the swallowtail butterfly Papilio laglaizei; right, the danaine 

 butterfly Ideopsis daos. All from New Guinea. {After Punnett, 1915, 

 Mimicry in Butterflies, Cambridge University Press. ) 



