Ecological Animal Geography
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A near fine copy in the publisher's original gilt-blocked cloth. Slightest suggestion only of dust-dulling and toning. Remains particularly well-preserved overall; tight, bright, clean and strong. ; 597 pages; An authorized, rewritten edition. Prepared by W. C. Allee and Kark Schmidt. Subjects: Zoogeography. Animal ecology.
indicaThus the flounder, Pleuronectes flesus, which frequently ascends the European rivers, does not become sexually mature in them. A number of fishes entering the eastern Baltic from the North Sea do not spawn there, Cottus bubalis and Gobius niger, for example. 25 The oyster plantations of the river mouths but whether this is a cause or an effect tions that fresh water checks fertility. ECOLOGICAL FOUNDATIONS OF ZOOGEOGRAPHY 40 west coast of France would die out if they were not
animals are least limited in dispersal by physical factors. air offers no barriers; only the low temperature and lessened density at high altitudes may affect flight. Deserts, mountains of The moderate height, and seas of not too great extent are not barriers for good fliers. However, there is great variation in the power of flight in different groups of flying animals. Among the insects, forms with limited flight are usually restricted The number of genera of limited distribution, inhabit-
barriers in separating interbreeding of greatest importance to mutational evolution. individuals from another area can enter a partially isolated group, the newly acquired effective mutational changes will be brought with them, and the differentiation of the group from the ancestral form is thereby retarded, and this relation may be reciprocal. With complete isolation, the groups differentiate first into varieties and subspecies, and then, with longer periods of time, into wholly distinct
Pyrenees to the Himalayas and from Syria and Abyssinia have their special species of ibex, distinguished by the form of their horns but otherwise and still completely fertile with each other.* The mountains of middle and south Germany have numerous geographic races of the carabid beetle, Carabus silvestris, usually peculiar to the special districts. Vicarious beetles are known from the mountains of Africa, such as the genus Carabomorphus on Kilimanjaro and the Gurui Mountain, and Orinodromus on
consideration of the mammals, has adopted a quite similar division. Wallace believed that this division into "regions" would apply to all fruitless as a means HISTORICAL ZOOGEOGRAPHY 117 groups of animals, and under the weight of his prestige, the delimitation and subdivision of the faunal regions have long constituted one of the principal branches of zoogeographic inquiry. The belief that there is a division into faunal regions of general validity for all the classes of animals cannot be