102 ECOLOGICAL FOUNDATIONS OF ZOOGEOGRAPHY 



consequence of changes in climate and vegetation. The alpine hare 

 (Lepus timidus) is found in Ireland and the Alps as well as in northern 

 Europe and Asia; the ptarmigan (Lagopus mutus) has representatives 

 in the Alps, the Pyrenees, and the Caucasus. These instances, in which 

 there are isolated outliers of an otherwise arctic range, are amply ac- 

 counted for by the southward extension of a cold climate in the glacial 

 period. Subfossil bones testify to the former presence of the ptarmigan 

 and alpine hare in central Europe; with the retreat of the glaciers, 

 they withdrew to the north and to the higher altitudes of the moun- 

 tains. A whole series of arctic animals (and plants as well) are to be 

 found on Mount Washington in the White Mountains of New Hamp- 

 shire. Their relatives, usually of the same species, are to be found in 

 Labrador and Greenland. 8 Discontinuity of range is accordingly ex- 

 plained by extinction in the intermediate area, in consequence of al- 

 tered habitat conditions. 



The converse reasoning is also possible, and climatic changes may 

 be inferred from the composition and distribution of faunae. The 

 abundance and wide distribution of the remains of steppe animals, 

 such as the saiga antelope, horse, gopher, and jerboa, in alluvial de- 

 posits make it probable that a steppe period followed the glacial period 

 in central Europe, although the evidence for the existence of such a 

 steppe period is far from being as abundant or conclusive as that for 

 glaciation. 9 Such distribution of steppe conditions in the past would 

 explain numerous instances of discontinuous ranges, such as that of the 

 shrew, Myogale, mentioned above. In a limited arid area in Moravia, 

 covered only with a little coarse grass and a few stunted bushes, Bun- 

 found more than eighty species of Orthoptera which were wholly unlike 

 those of the surrounding territory and exhibited a high degree of re- 

 semblance to the fauna of the Volga valley. He explains this area, prob- 

 ably correctly, as a faunal island, a relict of the steppe period. 10 



As has been stated previously, such survivors of a former period, 

 when habitat conditions and faunal relations were different from those 

 of the present, are termed relicts, and one speaks of glacial relicts, 

 steppe relicts, marine relicts, etc. The changed conditions may not be 

 climatic ones, and every kind of habitat factor may be involved. There 

 are relicts from periods when the competition in an animal community 

 was different. The rise of new competitors, better adapted than the 

 older forms to engage in the struggle for existence, leads to the destruc- 

 tion or dispersal of the older forms, and the few which survive, whether 

 by isolation or by exceptional ability to meet competition, appear as 

 anachronisms, i.e., relicts, in the wholly changed environment. This is 



