| → most. 1859 1860 1861 1869 1872 |
| most. And we have seen in the chapter on the Struggle for 1866 |
|
| → And we have seen in the chapter on the Struggle for 1859 1860 1861 1869 1872 |
| OMIT 1866 |
|
| → OMIT 1861 1866 1869 1872 |
| on my theory, 1859 1860 |
|
| → far less from each other 1872 |
| from each other far less 1859 1860 1861 1866 1869 |
|
| → OMIT 1869 1872 |
| species and species of the same 1859 1860 1861 1866 |
|
| → I have sought 1869 1872 |
| let us seek 1859 1860 1861 1866 |
|
|
that as new species in the course of time are formed through natural selection, others will become rarer and rarer, and finally extinct. The forms which stand in closest competition with those
modification and improvement, will naturally suffer
→most.
→And we have seen in the chapter on the Struggle for
Existence that it is the most closely-allied forms,— varieties of the same species, and species of the same genus or of related genera,— which, from having nearly the same structure, constitution, and habits, generally come into the severest competition with each
each new variety or species, during the progress of its formation, will generally press hardest on its nearest kindred, and tend to exterminate them. We see the same process of extermination amongst our domesticated productions, through the selection of improved forms by man. Many curious instances could be given showing how quickly new breeds of cattle, sheep, and other animals, and varieties of flowers, take the place of older and inferior kinds. In Yorkshire, it is historically known that the ancient black cattle were displaced by the long-horns, and that these "were swept away by the short-horns" (I quote the words of an agricultural writer) "as if by some murderous pestilence." |
|
|
| The principle, which I have designated by this term, is of high
→OMIT
and explains, as I believe, several important facts. In the first place, varieties, even strongly-marked ones, though having somewhat of the character of species— as is shown by the hopeless doubts in many cases how to rank them— yet certainly differ
→far less from each other
than do good and distinct species. Nevertheless, according to my view, varieties are species in the process of formation, or are, as I have called them, incipient species. How, then, does the lesser difference between varieties become augmented into the greater difference between species? That this does habitually happen, we must infer from most of the innumerable species throughout nature presenting well-marked differences; whereas varieties, the supposed prototypes and parents of future well-marked species, present slight and ill-defined differences. Mere chance, as we may call it, might cause one variety to differ in some character from its parents, and the offspring of this variety again to differ from its parent in the very same character and in a greater degree; but this alone would never account for so habitual and large
of difference as that between
of the same
→OMIT
genus. |
|
| As has always been my practice,
→I have sought
light on this
|
