V 
NATURAL SELECTION 
111 
stomach adapted to digest vegetable matter alone, or flesh 
alone, draws more nutriment from these substances. So, in 
the general economy of any land, the more widely and 
perfectly the animals and plants are diversified for different 
habits of life, so will a greater number of individuals be 
capable of there supporting themselves.” 1 
The most closely allied Species inhabit distinct Areas. 
One of the curious results of the general action of this 
principle in nature is, that the most closely allied species — 
those whose differences though often real and important are 
hardly perceptible to any one but a naturalist — are usually 
not found in the same but in widely separated countries. 
Thus, the nearest allies to our European golden plover are 
found in North America and East Asia ; the nearest ally 
of our European jay is found in Japan, although there are 
several other species of jays in Western Asia and North 
Africa; and though we have several species of titmice in 
England they are not very closely allied to each other. 
The form most akin to our blue tit is the azure tit of 
Central Asia (Parus azureus); the Parus ledouci of Algeria 
is very near our coal tit, and the Parus lugubris of South- 
Eastern Europe and Asia Minor is nearest to our marsh tit. 
So, our four species of wild pigeons — the ring-dove, stock¬ 
dove, rock-pigeon, and turtle-dove — are not closely allied to 
each other, but each of them belongs, according to some 
ornithologists, to a separate genus or subgenus, and has its 
nearest relatives in distant parts of Asia and Africa. In 
mammalia the same thing occurs. Each mountain region of 
Europe and Asia has usually its own species of wild sheep 
and goat, and sometimes of antelope and deer; so that in 
each region there is found the greatest diversity in this 
class of animals, while the closest allies inhabit quite distinct 
and often distant areas. In plants we find the same 
phenomenon prevalent. Distinct species of columbine are 
found in Central Europe (Aguilegia vulgaris), in Eastern 
Europe, and Siberia (A glandulosa), in the Alps (A. Alpina), 
in the Pyrenees (A. pyrenaiea), in the Greek mountains (A. 
ottonis), and in Corsica (A. Bernardi), but rarely are two 
1 Origin of Species, p. 89. 
