Whence it inevitably follows, as a matter of simple logic, that where divergence has occurred, intercrossing and interbreeding must in some way have been lessened or prevented.
These two local varieties, being by the terms of his supposition better adapted to the environment than the freely interbreeding forms in other parts of the general area, increase till they supplant these original forms.
Its importance, indeed, can only be denied by denying the swamping effects of intercrossing, and such denial implies the tacit assumption that interbreeding and interblending are held in check by some form of segregation.
Stragglers from one group into the other would stand a chance of elimination before interbreeding was effected.
No amount of promiscuous interbreeding of crabs could reduce the cuticle to a level indefinitely below that of any of the interbreeding individuals.
AN] Its importance can, indeed, only be denied by denying the swamping effects of intercrossing, and such denial implies the tacit assumption that interbreeding and interblending are held in check by some form of segregation.
The interbreeding within this area keeps the species one and homogeneous, notwithstanding its wide range, and, at the same time, prevents intercrossing with allied species with different breeding-grounds.
Elimination may and does give rise to progress in any given group as a group; it does not and cannot give rise to differentiation and divergence, so long as interbreeding with consequent interblending of characters be freely permitted.
It tends to check, and, if the offspring always possessed the blended character of both parents, would be absolutely fatal to, divergence of character within the interbreeding members of a species.
Amalgamation is a biological process, the fusion of races by interbreeding and intermarriage.
As a member of a race, he transmits by interbreeding a biological inheritance.
Interbreeding has broken up the ancient stocks, and interaction and imitation have created new national types which exhibit definite uniformities in language, manners, and formal behavior.
Neither interbreeding nor interaction has created, in what the French term "nationals," a more than superficial likeness or like-mindedness.
These races, when kept as far as possible from interbreeding with other races, have shown wonderfully persistent characteristics for a great many centuries.
With Sheep there has often been long-continued interbreeding within the limits of the same flock; but whether the nearest relations have been matched so frequently as in the case of Shorthorn cattle, I do not know.
Nevertheless, most great breeders of sheep have protested against close interbreeding prolonged for too great a length of time.
With Cattle there can be no doubt that extremely close interbreeding may be long carried on, advantageously with respect to external characters and with no manifestly apparent evil as far as constitution is concerned.
From this study and his own experience, he concludes that close interbreeding is necessary to ennoble the stock; but that in effecting this the greatest care is necessary, on account of the tendency to infertility and weakness.
Now it deserves especial notice, that the two last sows produced by this long course of interbreeding were sent to other boars, and they bore several litters of healthy pigs.
Although free crossing is a danger on the one side which every one can see, too close interbreeding is a hidden danger on the other side.
Where the ranges of two nearly allied species do overlap interbreeding probably will take place.
I have known too of one undoubted case of the interbreeding of the South African hartebeest (B.
Interbreeding of Allied Species That these recognition marks prevent the intercrossing of allied species and the production of infertile hybrids appears to be pure fiction.
From the most northern colonies as far south as Florida there was much contact resulting in the interbreeding of Indians and Negroes.
Interbreeding with both races they passed either to the blacks or to the whites.
Younger males, being thus expelled and wandering about, would, when at last successful in finding a partner, prevent too closeinterbreeding within the limits of the same family.
Ambitious and far-seeing, Philip Hardin unfolds the cherished plan of extending slavery to the West.
Just as we have seen that intercrossing is not necessarily good, we shall be forced to admit that close interbreeding is not necessarily bad.
It appears probable, then, that it is not interbreeding in itself that is hurtful, but interbreeding without rigid selection or some change of conditions.
And thus, the strange fact of the increase of fertility in the successive generations of artificially fertilised hybrids may, I believe, be accounted for by close interbreeding having been avoided.
The effects of close interbreeding on animals, judging again from plants, would be deterioration in general vigour, including fertility, with no necessary loss of excellence of form; and this seems to be the usual result.
Moreover, the fertilisation of a flower by its own pollen corresponds to a closer form of interbreeding than is possible with ordinary bi-sexual animals; so that an earlier result might have been expected.
When hybrids are capable of breeding inter se, their descendants are more or less sterile, and they often become still more sterile in the later generations; but then close interbreeding has hitherto been practised in all such cases.
The presence of a body of non-interbreeding immigrants is likely to produce the adverse results already discussed in the earlier part of this chapter.
The interbreeding is too slow at present to be conspicuous, and hence its effects are little noticed.
A biological objection has also been alleged, in the possibility of interbreedingbetween the yellow and white races.
The records of travellers provide certain information which helps us to form reliable though limited conclusions as to the results of the +interbreeding of different human races+.
Sebright continued closely interbreeding some owl-pigeons, until from their extreme sterility he as nearly as possible lost the whole family.
Analogous cases of closeinterbreeding are given in a pamphlet published by Mr. C.
This failure of fertility shows that the evil results of interbreeding are independent of the augmentation of morbid tendencies common to both parents, though this augmentation no doubt is often highly injurious.
With hermaphrodites of all kinds, if the sexual elements of the same individual habitually acted on each other, the closest possible interbreedingwould be perpetual.
The evil consequences of long-continued close interbreeding are not so easily recognised as the good effects from crossing, for the deterioration is gradual.
Also experiments with the interbreedingof animals have shown similar results.
If evolution be true, we would expect a frequent interbreeding and interchanging of species.
It certainly would be impossible for one single pair to have become the ancestors of the human race, without mixing and interbreeding with their kindred primates.
Interbreeding of the resident population with newcomers may overshadow any modifications which might have appeared as a result of insular isolation, especially modifications which have little adaptive significance.
Experiments in interbreeding of cattle go to prove that in some cases, at least, this may be continued for many generations with no unfavorable results.
McGraw[15] says "there can be no doubt that close and continual interbreeding has taken place time and again, without evident injurious consequences, among simple and uncultivated communities.
Let those so minded ask themselves the question, If promiscuous interbreeding were to take place, what would become of the species?
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "interbreeding" in a variety of sentences. We hope that you will now be able to make sentences using this word.
