Native species

“ The conception that different tribes at different times and in distant countries would have used the wild plants of their native regions seems far more natural than that all should have obtained plants for cultivation from the same source or locality. ”

“ It is not that these countries, so rich in species, do not by a strange chance possess the aboriginal stocks of any useful plants, but that the native plants have not been improved by continued selection up to a standard of perfection comparable with that acquired by the plants in countries anciently civilised. ”

“ The zoological works of Fleming, Jenyns, Yarrell, Bell, and W. Thompson, have enumerated the species and treated of the distribution of our indigenous animals, those of Smith, Hooker, Lindley, Babington, Henslow, and especially Watson, have done the same service for our native flora; but the history of the formation, if I may so say, of that fauna and flora, remains to be investigated. This essay is offered as a contribution towards such a history.
There are three modes in which an isolated area may become peopled by animals and plants. ”

“ As the plants and animals migrated southward, they will have become mingled in the one great region with the native American productions, and would have had to compete with them; and in the other great region, with those of the Old World. Consequently we have here everything favourable for much modification,— for far more modification than with the Alpine productions, left isolated, within a much more recent period, on the several mountain ranges and on the arctic lands of Europe and North America. ”

“ Now, by the side of the cultivated species, a native of the New World, we can place a wild variety, indigenous to the Old World, common in our own country, and, indeed, in all the countries of temperate Europe ”

“ Whatever the conclusions may be with regard to the origin of man, naturalists of the present day very generally agree, that there was no one universal centre of propagation for plants and animals; but that the same conditions of soil, moisture, heat, and geographical situation, always produce a similarity of species; or, what is equivalent, that there were many primary centres, each originating species, which spread out from these centres and covered the earth. ”

“ How many of those birds and insects in North America and Europe, which differ very slightly from each other, have been ranked by one eminent naturalist as undoubted species, and by another as varieties, or, as they are often called, as geographical races! Many years ago, when comparing, and seeing others compare, the birds from the separate islands of the Galapagos Archipelago, both one with another, and with those from the American mainland, I was much struck how entirely vague and arbitrary is the distinction between species and varieties. ”

“ Firstly.—If the eleven chief races have not arisen from the variation of some one species, together with its geographical races, they must be descended from several extremely distinct aboriginal species; for no amount of crossing between only six or seven wild forms could produce races so distinct as Pouters, Carriers, Runts, Fantails, Turbits, Short-faced Tumblers, Jacobins, and Trumpeters. ”

“ On these same principles, we can understand, as I have endeavoured to show, why oceanic islands should have few inhabitants, but of these a great number should be endemic or peculiar; and why, in relation to the means of migration, one group of beings, even within the same class, should have all its species endemic, and another group should have all its species common to other quarters of the world. ”

“ Is there anything in similarity of form, anatomy, structure, size, color, food, habits, habitat, longevity, modes of propagation, terms of gestation, and capacity for inter-breeding between certain flora and fauna of the Eastern Continents and the Western, which would suggest that many species and varieties so widely separated might have come originally from the same locality and ancestry? Are plants and animals always improved, developed, and rendered prolific more by being moved one way than another? ”

“ The air, the earth, the undergrowth, the tree-trunks, the flowers, and the fruits, all support their specially adapted tribes of birds. Each species fills a place in nature, and can only continue to exist so long as that place is open to it; and each has become what it is in every detail of form, size, structure, and even of colour, because it has inherited through countless ancestral forms all those variations which have best adapted it among its fellows to fill that place, and to leave behind it equally well adapted successors. ”

“ Having alluded to the subject of reversion, I may here refer to a statement often made by naturalists—namely, that our domestic varieties, when run wild, gradually but invariably revert in character to their aboriginal stocks. Hence it has been argued that no deductions can be drawn from domestic races to species in a state of nature. ”

“ If it would not be too troublesome, do you not think it would be very interesting, and give a very good idea of your Flora, to divide the species into three groups, viz., (a) species common to the old world, stating numbers common to Europe and Asia; (b) indigenous species, but belonging to genera found in the old world; and (c) species belonging to genera confined to America or the New World. To make (according to my ideas) perfection perfect, one ought to be told whether there are other cases, like Erica, of genera common in Europe or in Old World not found in your area. ”

“ In the second and fourth chapters, on Variation and on Natural Selection, I have attempted to show that within each country it is the widely ranging, the much diffused and common, that is the dominant species, belonging to the larger genera in each class, which vary most. The varieties, or incipient species, thus produced, ultimately become converted into new and distinct species; and these, on the principle of inheritance, tend to produce other new and dominant species. ”

“ If, for example, all the species of a genus occur in North America, some, or even all, of them, migrating into the Neotropical region in winter, while there are no peculiar Neotropical species, then we must class that genus as strictly Nearctic ”

“ The diversity and specialization of the forms of these animals is, therefore, easily explained by the fact, that, once introduced they have been left to multiply under the influence of a variety of local conditions, which inevitably lead, in the course of ages, to the formation of new varieties and new species. ”

“ I cannot doubt that if other animals and plants, equal in number to our domesticated productions, and belonging to equally diverse classes and countries, were taken from a state of nature, and could be made to breed for an equal number of generations under domestication, they would on an average vary as largely as the parent species of our existing domesticated productions have varied. ”

“ Hence, we see that certain plants growing on the more lofty mountains of the tropics in all parts of the world, and on the temperate plains of the north and south, are either the same species or varieties of the same species. ”

“ Probably no region is as yet fully stocked, for at the Cape of Good Hope, where more species of plants are crowded together than in any other quarter of the world, some foreign plants have become naturalised, without causing, as far as we know, the extinction of any natives. ”

“ It is certain that he can largely influence the character of a breed by selecting, in each successive generation, individual differences so slight as to be inappreciable except by an educated eye. This unconscious process of selection has been the great agency in the formation of the most distinct and useful domestic breeds. That many breeds produced by man have to a large extent the character of natural species, is shown by the inextricable doubts whether many of them are varieties or aboriginally distinct species. ”

“ In ordinary cases nature has not allowed her race to {11} be contaminated with a cross of another race, and agriculturists know how difficult they find always to prevent this,—effect would be trueness. This character and sterility when crossed, and generally a greater amount of difference, are two main features, which distinguish domestic races from species. ”

“ The newly formed Forestry Departments of the English, Scottish, and Irish Boards of Agriculture have the results of experimental planting by arboriculturists to guide them in their choice of species. The opinion is sometimes expressed that British forests should be composed of indigenous species, on the principle that Nature has indicated which species are best adapted to our soil and climate. ”

“ By considering the nature of the plants or animals which have in any country struggled successfully with the indigenes, and have there become naturalised, we may gain some crude idea in what manner some of the natives would have had to be modified in order to gain an advantage over their compatriots; and we may at least infer that diversification of structure, amounting to new generic differences, would be profitable to them. ”

“ Natural selection occurs not only in the wild state, but is also active in cultivated fields. Here it regulates the struggle of the selected varieties and improved races with the older types, and even with the wild species. In a previous [803] lecture I have detailed the rapid increase of the wild oats in certain years, and described the experiments of Risler and Rimpau in the running out of select varieties. The agency is always the same. ”

“ Nevertheless, the fact remains indisputable that domesticated varieties of animals and of plants, which differ greatly from each other in structure, but which are certainly descended from the same aboriginal species, such as the races of the fowl, pigeon, many vegetables, and a host of other productions, are extremely fertile when crossed; and this seems to make a broad and impassable barrier between domestic varieties and natural species. ”

“ As showing how diversified are the means of occasional transport, I have discussed at some little length the means of dispersal of fresh-water productions.
If the difficulties be not insuperable in admitting that in the long course of time all the individuals of the same species, and likewise of the several species belonging to the same genus, have proceeded from some one source; then all the grand leading facts of geographical distribution are explicable on the theory of migration, together with subsequent modification and the multiplication of new forms. ”

“ But the differences between them are such as obtain between allied species generally. Large genera are composed, in great part, of such species; and it is interesting to show how the great and beautiful diversity within a large genus is brought about by the working of laws within our comprehension.
A few remarks on the way races are produced will be here in place. Naturalists have been generally inclined to attribute the formation of local varieties or races of a species to the direct action of physical conditions on individuals belonging to it which have migrated into new localities. ”

“ I am far from supposing that all the difficulties in regard to the distribution and affinities of the identical and allied species, which now live so widely separated in the north and south, and sometimes on the intermediate mountain ranges, are removed on the views above given. The exact lines of migration cannot be indicated. We cannot say why certain species and not others have migrated; why certain species have been modified and have given rise to new forms, while others have remained unaltered. ”

“ Respecting the indigenous species, ( G. herbaceum ) it is unnecessary to dilate, that one being already so well known in India, and indeed over all the warmer portions of the old world from the south of Europe, the northern limit of its cultivation, through the whole of the torrid' zone, and as being the species first and best known to mankind generally. ”

“ It is in this way that horticultural and agricultural experience contribute to the problem of the conversion of varieties into species, and to the explanation of the admirable adaptations of each organism to its complex conditions of life. In the long run new forms, distinguished from their allies by quite a number of new characters, would, by the extermination of the older intermediates, become distinct species. ”

“ If we turn to nature to test the truth of these remarks, and look at any small isolated area, such as an oceanic island, although the total number of the species inhabiting it, will be found to be small, as we shall see in our chapter on geographical distribution; yet of these species a very large proportion are endemic,—that is, have been produced there, and nowhere else. ”