ANIMAL INTER-RELATIONS 33 



one of the special kinds of protective resemblance of 

 one animal by another, in which the chief element 

 is a bluff — the imitation of the strong by the weak 

 or the distasteful by the edible. As a result of such 

 adaptations the actual edible quaUtics of wild animals 

 do not always become closely adjusted to the potential 

 enemies that exist in the community. 



We have not so far referred much to the special 

 inter-relations which exist between members of the 

 same species. The nature of direct competition 

 between individuals comes under population problems 

 in the community and is discussed in Chapters V and 

 VI. Lender this heading also comes the subject of 

 animal aggregations, although these have probably 

 formed the basis of sub-social behaviour upon which 

 evolution has worked in the production of social 

 groupings within the species (AUee, 1931). Social 

 inter-relations within the species are of two kinds, of 

 which the first is the sexual relation. The existence 

 of the sex chromosome mechanism of sex-determina- 

 tion usually produces equal numbers of males and 

 females in a species ; but from an ecological point 

 of view, as Dr. John R. Baker has pointed out to me, 

 the fertilization of sufficient females to keep the 

 species above a critical density of numbers could be 

 accomphshed by a fraction only of these males. This 

 is, in fact, the case wdth polygamous species such as 

 blackgame and Gamrnarus and others. We know 

 that a single male rabbit can successfully fertilize 

 forty females in one day. The superabundance of 

 males generally found in nature has led to the develop- 

 ment of competition between males for possession of 

 the females. We find among insects and birds and 

 mammals and most other groups above the lowest, 

 more or less highly developed courtship ceremonies 

 — or to use a non-committal term, epigamic behaviour. 

 Competition among the males is only one reason for 

 this behaviour, and there are a number of obscure 

 problems connected with it as yet unsolved (e.g. the 



