Origin of Species Variorum

→ by checking immigration and consequently competition, 1859 1860 1861 1866

OMIT 1869 1872

→ and 1859 1860 1861 1866 1869

at a slow rate; and 1872

→ importance in the production of new species. 1859 1860 1861 1866 1869

much importance. 1872

→ individuals supported on it will necessarily be very 1859 1860 1861 1866

inhabitants will be 1869 1872

→ fewness of individuals will greatly 1859 1860 1861 1866

this will 1869 1872

→ the appearance of 1859 1860 1861 1866 1869

OMIT 1872

↑ 4 blocks not present in 1859 1860; present in 1861 1866 1869 1872

The mere lapse of time by itself does nothing either for or against natural selection. I state this because it has been erroneously asserted that the element of time is assumed by me to play an all-important part in natural selection, as if all species were necessarily undergoing slow modification from some innate law. Lapse of time is only so far highly important, as it gives a better chance of beneficial variations arising, being selected, accumulated, and fixed, in relation to the slowly changing organic and inorganic conditions of life. It likewise favours the direct action of new or changed physical conditions of life.

→ species inhabiting it, will be found to be 1859 1860 1861

species inhabiting it will be found to be 1866

different species inhabiting it is 1869

species inhabiting it is 1872

→ else. 1859 1860 1861 1866

else in the world. 1869 1872

→ I do not doubt that 1859 1860

OMIT 1861 1866 1869 1872

in their structure and constitution. Lastly,

isolation

isolation,

→by checking immigration and consequently competition, will give time for

any

new variety to be

~~slowly~~

slowly

improved

improved;

→and this may sometimes be of →importance in the production of new species. If, however, an isolated area be very small, either from being surrounded by barriers, or from having very peculiar physical conditions, the total number of the →individuals supported on it will necessarily be very small; and →fewness of individuals will greatly retard the production of new species through natural selection, by decreasing the

chances

chance

of →the appearance of favourable

individual differences.

variations arising.

variations.

↑

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~~

total

number of

~~the~~

the

→species inhabiting it, will be found to be small, as we shall see in our chapter on

Geographical

geographical

Distribution;

distribution;

yet of

the

these

species a very large proportion are endemic,— that is, have been produced there, and nowhere →else. Hence an oceanic island at first sight seems to have been highly favourable for the production of new species. But we may thus

~~greatly~~

greatly

deceive ourselves, for to ascertain whether a small isolated area, or a large open area like a continent, has been most favourable for the production of new organic forms, we ought to make the comparison within equal times; and this we are incapable of doing.

Although →I do not doubt that isolation is of

great

considerable

importance in the production of new species, on the whole I am inclined to believe that largeness of area is

still

important,

importance,

~~more~~

especially

for

the production of

species

species,

which

shall

will

prove capable of enduring for a long period, and of spreading widely. Throughout a great and open area, not only will there be a better chance of favourable

variations,

variations

arising from the large number of individuals of the same species