Talk:Hybrid

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I am not sure how to work these two different definitions into the same article. Should it be separated into two articles. Where should go the discussion of hybrid vigor, the Green Revolution, F1 hybrids, F2 hybrids, diploid, triploid, tetraploid, etc.? Rmhermen 14:44, Nov 14, 2003 (UTC)

There is another issue: a hybrid is a cross between two specimen belonging to taxons below the genera level. (This includes crosses with subspecies varieties subvarieties and forms).

There is a second issue: a hybrid of two cultivars. Actually a cultivar is most often a hybrid in its own right. The way cultivars are reproduced is most often under controlled conditions and they can be clones. GerardM

In botany it is accepted to talk about taxons lower than subspecies. So when you have natural varieties, and cross them you get hybrids. This does explain to me why a hybrid can be stronger in botany and not in zoology. Can anyone explain WHY the concept of variety or form is absent in zoology? GerardM

Wouldn't that be breed for domestic animals at least? Rmhermen 21:50, Dec 11, 2003 (UTC)

A breed is indeed domestic. As such they are not taxonomically relevant. You do not find a "fresian holstein" for a cow or an "arabian thoroughbred" for a horse when studying the taxonomy of animals. GerardM

Contents 1 Question for the biologists: 2 Cypresses 3 66.42.123.130's edits 4 Wolphin 5 Hybrid Fish 6 What happens at the chromosome level in hybrid crosses? 7 Hybrid Ratites 8 Interfamilial Hybrids 9 Human/Neanderthal Hybrid

[edit] Question for the biologists:

Is this line from the 4th paragraph true, strictly speaking? 'To create specialised plants is called cross-fertilisation.' Is that actually the definition of 'cross-fertilisation'?

English is not my primary language but to me this fourth paragraph is wrong. GerardM 22:01, 23 Jul 2004 (UTC)

Can't you cross-fertilize for another reason? And wouldn't grafting, e.g., be another way of creating a specialized plant? Quill 22:01, 19 Jul 2004 (UTC)

A graft is special but it is not one organism they are two. The rootstock has properties that make for a more vibrant growth of the graft. A hybrid is one organism. GerardM 21:59, 23 Jul 2004 (UTC)

Cross-fertilization isn't really the correct term to use here, the sentence as it stands does not convery any information so I'm deleting it and adding a link to plant breeding where hybrids are discussed.--nixie 02:20, 1 Mar 2005 (UTC)

I don't think they should merge, because having two articles allows for more specified results... If you were looking for specific hybrids... I think parts of the "Hybrid" article sould assimilate to the other article.

When refering to plants cross pollination is probably a better term; cross fertilisation can also refer to the artificial fertilisation in animals. The generalised hybrid article makes this clearer but perhaps links to plant propagation would be appropriate?

[edit] Cypresses

Whilst the example of the cypresses is not untrue, it's not actually very pointful. Plants will readily hybridize with other plants of the same genus. All the other examples are animals, hybrids of which are much more unusual. I'm not sure the single plant example belongs here.

[edit] 66.42.123.130's edits

I'm not sure if this anon user's addition should even be kept on this page, but I thought I would at least format it correctly for the time being. [[User:Lachatdelarue|Lachatdelarue (talk)]] 12:53, 19 Sep 2004 (UTC)

It's a good question, Lach. I like the entry, but since this article is about biology (in the real world), perhaps this is misplaced. So where to put it? Another article, with a link at hybrid (disambiguation)? Quill 23:24, 20 Sep 2004 (UTC)

[edit] Wolphin

In the article, it says that a wolphin is a cross between a whale and a dolphin, but that's actually not true. It is a cross between a False Killer Whale and a Bottlenose Dolphin, both of which are dolphins, as the article it links to points out.

[edit] Hybrid Fish

I think that hybrid fish should be added to the list such as the stripe bass (a.k.a. striper), which is a mix of a large mouth bass and a small mouth bass, unless a hybrid fish article is already made (which i can't find it if there is one). If you can find out about any hybrid fish information please add a new section called hybrid fish.- Biggal6 12:51, 8 November 2005 (EST)

[edit] What happens at the chromosome level in hybrid crosses?

This has just been added by User:Pschemp:

Continuous backcrossing to one of the species, in an effort to make the resulting animal more like one of the original species does not guarantee that successive generations will be "mostly" or even a given percentage of that species. This is due to the fact that during meiosis, fifty percent of the parent's genetic material is selected, but the part is selected at random. Thus a hybrid does not pass on exactly half of the genes of each of the parental species. While the average may tend to one species or the other, it is technically possible to end up with an animal that is still genetically fifty percent of each of the original species, even many generations removed from the original cross. Thus, even after extensive breeding, a hybrid is still a hybrid, and can never become one of the original species or the other.

What is sorely missing is an explanation of whether crossing over occurs at hybrid meiosis or not, and what happens to unpaired chromosomes (if parental species differ in karyotype). I understand that in normal meiosis, there is at least one crossing over per chromosome to ensure proper segregation.

As the passage stands, the conclusion does not follow from the premises. - Samsara _contrib ^talk 00:31, 20 January 2006 (UTC)

I am countering the argument that since animal C (a hybrid of A and B)has been backcrossed X number of times to animal B, that it is now animal B. If you have a clearer way of explaining why this is not so, please help. (I'm trying to write this in a friendly manner for non-geneticists.) What I'm saying here is that in the cases where a fertile hybrid can be obtained (for example a wild and domestic cat cross where the F1 female is fertile), and then it is bred to a domestic, and the offspring bred to a domestic, etc...that you can't specify at any time down the line what ratio of domestic to wild cat is present due to random assortment of the chromosomes in meiosis. Thus one can't say, "after 100 of these crosses (or some other number), this cat is now completly the domestic species". Or even 99.9 percent domestic, because the random assortment can't be predicted. I don't know what happens to the unpaired chromosomes in this situation, but it isn't really relevant to the result as far as I can tell. As far as the crossing over, this almost assures that the gamete will have unequal contributions from the genetic material that the parent has inherited. Pschemp 01:21, 20 January 2006 (UTC)

If you keep pouring on chromosomes from one parental species (say, A), you will eventually end up with that species. In the vast number of species, there is no magic mechanism that ensures that it's always chromosomes from species B that make it to the next round! What you should be saying is that you can't be sure of the composition of a particular backcrossed individual, even though you can predict it on average. - Samsara _contrib ^talk 01:56, 20 January 2006 (UTC)

Maybe I shouldn't be applying logic to genetics, but its not my native science field so what the heck. By the way, your edits so far are great. Pschemp 03:18, 20 January 2006 (UTC)

That it tends toward average is exactly right but just as you can't make sure that chromosomes from the B species make it, you can't be sure they didn't make it either and thus you can't say that the result is an A species because that would mean it is 100% A and you can't know that for sure. The probability that there is much B left is low, but it exists, therefore maintaining the individual as a hybrid (technically). You can't make a hybrid into one species by continual crossing. There always exists the possibility (however low) that it contains genetic material from both parental species. Pschemp 02:40, 20 January 2006 (UTC)

Well, if you were really breeding and had enough money to spend, you would "build" genetic markers such as microsatellites, type them in each parental species and then use these genetic markers in the hybrid to determine how much of each species is in it. You would miss some double recombination events happening between markers, but your overall estimate would be very accurate. - Samsara _contrib ^talk 03:48, 20 January 2006 (UTC)

Nice! Something tells me that the people breeding animals in their backyards aren't exactly following that method :) Pschemp 04:09, 20 January 2006 (UTC)

[edit] Hybrid Ratites

Does anybody know of any instance of hybridization between ratites (Emu X Cassowary, Ostrich X Rhea, Greater Rhea X Lesser Rhea, etc.)? I have searched the internet endlessly and have found nothing on the subject. Has it been tried by ratite farmers? If nobody knows, I would at least like to hear opinions on the matter.

[edit] Interfamilial Hybrids

I added the interfamilial bit to the article & the Domestic Fowl & Guineafowl links and I also added the guineafowl hybrids to the list. The Information is indeed accurate as most classification schemes now classify the guineafowl in its own family, along with 7 other species. The guineafowl is a member of the Numididae and the Chicken & Peafowl are members of the Phaisanidae.

P.S. The wolfdog should be removed from the hybrid list as it is a list of interspecific hybrids and the polar bear & congolese spotted lion hybrids should also be removed as there is already a mention of Ursinae & Panthera hybrids.

[edit] Human/Neanderthal Hybrid

According to this article (http://www.livescience.com/humanbiology/061115_neanderthal_dna.html), there is no evidence for interbreeding of the two species based on a more recent report. So I'm removing that from the listing.