The Geographic Distribution of Closely Related Species1907 - 34 pages |
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Common terms and phrases
alg¿ American Ames Botanical Laboratory blephariglottis bolanderi boreale botanists California cernua chapmanii ciliaris closely allied closely related species cognate pairs coincident ranges Crataegus cristata distinguished distribution of species district Draba Draba verna effect England England Botanical Club evolution evolutionary extended facts fimbriata Florida form of isolation fresh water algae gametes genus GEOGRAPHIC DISTRIBUTION geographic evidence geographic isolation Georgia geotropism Gulick habitats heredity high arctic regions hybrid interbreeding Intricat¿ Jersey Jordan Jordan's law Lindl longidens maternal representatives Michigan modifiability monotypic Moritz Wagner Muta Mutation Theory Nägeli Natural Selection nearest related species Newfoundland North America North Carolina northern odorata Ontario Orchidace¿ Organic geography Origin of Species Orthogenesis overlies the range pairs of kinds parent species Pennsylvania polytypic psycodes regard ROBERT GREENLEAF Rosen separated sharply alternative side specific distribution specimens subspecies taxonomy tion topographical unit characters varieties vegetable kingdom Virginia Vries widely zoologists
Popular passages
Page 208 - Every species has come into existence coincident both in time and space with a pre-existing closely allied species" connects together and renders intelligible a vast number of independent and hitherto unexplained facts.
Page 219 - ... variations would enable their possessors little by little to gain on the parent stock, so that a new species would be established side by side with the old, or on whether a wide fluctuation or mutation would give rise to a new species which would hold its own in. competition with its parent. In theory, either of these conditions might exist. In fact, both of them are virtually unknown. In nature a closely related distinct species is not often quite side by side with the old. It is simply next...
Page 214 - Very frequently, if not always, the character that has been once crossed has been affected by its opposite with which it was mated and whose place it has taken in the hybrid. It may be extracted therefrom to use in a new combination, but it will be found to be altered. This we have seen to be true for almost every characteristic sufficiently studied — for the comb form, the nostril form, cerebral hernia, crest, muff, tail length, vulture hock, foot feathering1, foot color, earlobe and both general...
Page 219 - The principles set forth by Wagner "have never been confuted, 1 scarcely even attacked, so far as the present writer remembers, but in the literature of the present day they have been almost universally ignored." The question is much discussed whether minute variations may serve to establish a new species in the presence of a parent species, or whether wide fluctuation or mutation may do so. " In thecry either of these conditions might exist.
Page 219 - I am in hearty accord, except with the declaration that geographical isolation is a 'factor or condition in the formation of every species, race or tribe of animal or plant * * * on the face of the earth'; especially if the isolation here meant implies a physical barrier, 'geographical or climatic,' to the continuous range of closely allied forms, as the general context seems clearly to involve.
Page 215 - Single comb is one unit and pea 1 Besides the Mendelian results see also de Vries (: 03, 2, p. 396 el seg.) on the crossing of mutants with the parent species. comb is a different unit, but they are not sharply separable. Crest and no crest are units, but they run into each other in hybridizing. Unit characters may show transitions, and, if so, they may have originated gradually, so far as I see. It does not follow that they must have originated gradually
Page 239 - virtually unknown." In the vegetable kingdom this is likely to be an arduous task. The indications are that the adherents of Mutation will be able to bring forward enough cases of social distribution to render phytogeographic weapons useless in the attack upon this Theory.
Page 220 - The contention is not that species are occasionally associated with physical barriers, which determine their range, and which have been factors in their formation. It may be claimed that such conditions are virtually universal;" and again: "Given any species in any region, the nearest related species is not likely to be found in the same region nor in a remote region, but in a neighboring district separated from the first by a barrier of some sort.
Page 214 - ... extracted therefrom to use in a new combination, but it will be found to be altered. This we have seen to be true for almost every characteristic sufficiently studied — for the comb form, the nostril form, cerebral hernia, crest, muff, tail length, vulture hock, foot- feathering, foot color, earlobe, and both general and special plumage color. Everywhere unit characters are changed by hybridizing. How does this fact bear on the rival theories of evolution ? It has an important bearing on them....
Page 236 - ... from New England to Florida and west to Wisconsin and quite surrounds the other, a very rare species occurring sporadically in Vermont, Massachusetts, Connecticut, New York and New Jersey. Here again geographic isolation is wanting. The conclusion from this examination of North American Orchidacese is that cognate pairs of kinds with uniform or widely coincident ranges are too numerous to leave any force at all in Jordan's law in its broad sense as regards this family in our flora. If one member...