122 JUNGLE FOLK 



The cormorant family furnishes a very good example 

 of the manner in which new species arise quite inde- 

 pendently of natural selection. Notwithstanding their 

 world-wide distribution, all cormorants belong to one 

 genus, which is divided up into thirty-seven species. 

 Of these no fewer than fifteen occur in New Zealand — 

 a country not characterised by a large avifauna. 



One species — the large cormorant (Phalacocorax 

 carbo) — flourishes in almost every imaginable kind 

 of climate and among all sorts and conditions of 

 birds and beasts. Yet in New Zealand, in a country 

 where the conditions of existence vary but little, 

 cormorants have split up into fifteen species. It 

 is therefore as clear as anything can be in nature 

 that we must look to some cause other than natural 

 selection for an explanation of the multiplicity of 

 species of cormorant in New Zealand. It seems to 

 me that the solution of this puzzle lies in the fact that 

 the conditions of life are comparatively easy in New 

 Zealand. Consequently a well-equipped bird like a 

 cormorant is allowed a certain amount of latitude as to 

 its form and colouring. In places where the struggle 

 for existence is very severe, where organisms have their 

 work cut out to maintain themselves, the chances are 

 that every unfavourable variation will be wiped out by 

 natural selection ; but if the struggle is not particu- 

 larly severe, or if a species has something in hand, it 

 can afford to dispense with part of its advantage and 

 still survive. Thus it is that in New Zealand we see 

 a number of different species of cormorant living side 

 by side. De Vries likens natural selection to a sieve 



