Origin of Species Variorum

→ each other, or, 1869 1872

or, 1859 1860 1861 1866

→ alike. 1869 1872

like each other. 1859 1860 1861 1866

→ variation and natural 1872

natural 1859 1860 1861 1866 1869

→ probably in a 1872

in a quite 1859 1860 1861 1866

in a 1869

→ of the inhabitants on each other in leading to the preservation of different modifications; 1869 1872

and reaction, in their mutual struggles for life;— 1859 1860 1861 1866

→ in the struggle for life being, 1869 1872

being, 1859 1860 1861 1866

→ There is no evidence, 1872

I believe, 1859 1860 1861 1866 1869

→ of the existence of any 1872

in no 1859 1860 1861 1866 1869

→ If 1866 1869 1872

If, for instance, 1859 1860 1861

→ after having long competed 1866 1869 1872

which stand in direct competition 1859 1860 1861

→ in their old home, were to migrate in 1866 1869 1872

migrate in 1859 1860 1861

→ or at all modified. 1861 1866 1869 1872

modified. 1859 1860

as far as we positively know, produces organisms quite

like,

→each other, or, as we see in the case of

varieties

varieties,

nearly →alike. The dissimilarity of the inhabitants of different regions may be attributed to modification through →variation and natural selection, and →probably in a subordinate degree to the

direct

definite

influence of different physical conditions. The

degree

degrees

of dissimilarity will depend on the migration of the more dominant forms of life from one region into another having been

effected with

prevented

....

more or less

ease,

effectually,

effectually prevented,

at periods more or less remote;— on the nature and number of the former

immigrants; —

immigrants;—

and on

their

the

action →of the inhabitants on each other in leading to the preservation of different modifications; the relation of organism to organism →in the struggle for life being, as I have already often remarked, the most important of all relations. Thus the high importance of barriers comes into play by checking migration; as does time for the slow process of modification through natural selection. Widely-ranging species, abounding in individuals, which have already triumphed over many competitors in their own widely-extended

homes

homes,

will have the best chance of seizing on new places, when they spread into new countries. In their new homes they will be exposed to new conditions, and will frequently undergo further modification and improvement; and thus they will become still further victorious, and will produce groups of modified descendants. On this principle of inheritance with modification, we can understand how it is that sections of genera, whole genera, and even

families

families,

are confined to the same areas, as is so commonly and notoriously the case.

→There is no evidence, as was remarked in the last chapter, →of the existence of any law of necessary development. As the variability of each species is an independent property, and will be taken advantage of by natural selection, only so far as it profits

the

each

individual in its complex struggle for life, so the

degree

amount

of modification in different species will be no uniform quantity. →If a number of species, →after having long competed with each

other,

other

→in their old home, were to migrate in a body into a new and afterwards isolated country, they

will

would

be little liable to modification; for neither migration nor isolation in themselves

can do

can effect

effect

anything. These principles come into play only by bringing organisms into new relations with each other, and in a lesser degree with the surrounding physical conditions. As we have seen in the last chapter that some forms have retained nearly the same character from an enormously remote geological period, so certain species have migrated over vast spaces, and have not become greatly →or at all modified.

According to

these views, it is

obvious,

obvious

that the several species of the same genus, though inhabiting the most distant quarters of the world,