Agencies which Govern the Distribution of Life
| Autor: | A. Brazier Howell |
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| Rok vydání: | 1922 |
| Předmět: | |
| Zdroj: | The American Naturalist. 56:428-438 |
| ISSN: | 1537-5323 0003-0147 |
| DOI: | 10.1086/279883 |
| Popis: | THE problems presented by the distribution of plants and animals is a fertile field for investigation. These problems are essentially ecological in character, for often, perhaps always, the range of a species or genus is dependent upon a number of diverse environmental factors, some of which are readily apparent, while others are obscure; but always they merit careful study. In investigating and mapping the ranges of living organisms and in following the evolutional tendencies of species in so far as we are able, environment and its influences are of the greatest moment, especially from an ecological standpoint. Botanical subjects may usually be allocated in relation to their surroundings with considerably greater ease than can active forms of life, for the former are acted upon oiily by the agencies to be found in one spot, while the latter may experience not only all the influences operative over several square miles, more or less, of diversified territory, but, in the case of a migratory bird or mammal, will be subject during a part of the year to environmental factors of which we may lukow nothing. Whether a species is common or rare in a certain area depends upon its rate of reproduction, which is usually entirely adequate unless new and disturbing influences have been introduced; upon the lumber of favorable or unfavorable conditions which it encounters, the amount of competition with which it has to contend, and its phylogenetic characters, as to whether it be of a plastic type or one which is senescent and overspecialized: all of which may be summed up in the phrase 'adaptability to its habitat.' 428 |
| Databáze: | OpenAIRE |
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