Inbreeding.

<body bgcolor="#800000" text="#FFFF00" link="#FFFF00" vlink="#00FF00" alink="#00FFFF"> <p><b><span lang="EN-GB" style="mso-ansi-language: EN-GB"><font face="Garamond" color="#FFFF00" size="5">   PROS AND CONS OF INBREEDING</font></span></b></p> <p><span lang="EN-GB" style="mso-ansi-language: EN-GB"><font face="Garamond"><i><font size="4" color="#FFFFFF">SOK 2003-2, Copyright 1996, 2001, 2003 Sarah Hartwell <o:p> </font> </i> <font size="4" color="#FFFFFF"> </o:p> </font></font></span></p> <p align="left"><font face="Garamond"><img border="0" src="images/cat.bmp" width="30" height="30"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font size="4" color="#FFFF00">  Inbreeding</font> <font face="Garamond" size="4" color="#FFFFFF"> is the mating together of closely related cats, for example mother/son, father/daughter, sibling/sibling matings and half-sibling/half-sibling. It is the pairing of animals which are more closely related than the average population. For breeders, it is a useful way of fixing traits in a breed - the pedigrees of some exhibition cats show that many of their forebears are closely related. For example, the name of Fan Tee Cee (shown in the 1960s and 1970s) appeared in more and more Siamese pedigrees, sometimes several times in a single pedigree, as breeders were anxious to make their lines more typey. Superb specimens are always much sought after for stud services or offspring (unless they have already been neutered; cloning may solve that problem in the future) having won the approval of show judges. <o:p>  </font> </b> </span></font></p> <p align="center"><font face="Garamond"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b> <font face="Garamond" size="4" color="#FFFFFF">  <img border="0" src="images/bar080.gif" width="604" height="12"></font> </b> </span></font></p> <p align="left"><font face="Garamond"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font size="4" color="#FFFFFF">  </font> </b> </span><img border="0" src="images/cat.bmp" width="30" height="30"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font size="4" color="#FFFFFF"> </font> <font size="4" color="#FFFF00">To produce cats </font> <font size="4" color="#FFFFFF"> which closely meet the breed standard, breeders commonly mate together animals which are related and which share desirable characteristics. Over time, sometimes only one or two generations, those characteristics will become homozygous (genetically uniform) and all offspring of the inbred animal will inherit the genes for those characteristics (breed true). Breeders can predict how the offspring will look. "Line-breeding" is not a term used by geneticists, but comes from livestock husbandry. It indicates milder forms of inbreeding. Line-breeding is still a form of inbreeding i.e. breeding within a family line and includes cousin/cousin, aunt/nephew, niece/uncle and grandparent/grandchild. The difference between line-breeding and inbreeding may be defined differently for different species of animals and even for different breeds within the same species. It is complicated by the fact that a cat's half-brother might also be her father!<o:p> </o:p> </font> </b> </span></font></p> <p align="center"><font face="Garamond"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b> <font face="Garamond" size="4" color="#FFFFFF"> <img border="0" src="images/bar080.gif" width="604" height="12"></font> </b> </span></font></p> <p align="left"><font face="Garamond"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font size="4" color="#FFFF00">  </font> </b> </span><img border="0" src="images/cat.bmp" width="30" height="30"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font size="4" color="#FFFF00"> However, inbreeding holds potential problems. </font> <font size="4" color="#FFFFFF"> The limited gene-pool caused by continued inbreeding means that deleterious genes become widespread and the breed loses vigour. Laboratory animal suppliers depend on this to create uniform strains of animal which are immuno-depressed or breed true for a particular disorder e.g. epilepsy. Such animals are so inbred as to be genetically identical (clones!), a situation normally only seen in identical twins. Similarly, a controlled amount of inbreeding can be used to fix desirable traits in farm livestock e.g. milk yield, lean/fat ratios, rate of growth etc. In human terms, inbreeding is considered incest; cats do not have incest taboos.<o:p> </o:p> </font> </b> </span></font></p> <p align="center"><font face="Garamond"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b> <font face="Garamond" size="4" color="#FFFFFF"> <img border="0" src="images/bar080.gif" width="604" height="12"></font> </b> </span></font></p> <p align="left"><font face="Garamond"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font size="4" color="#FFFF00">  </font> </b> </span><img border="0" src="images/cat.bmp" width="30" height="30"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font size="4" color="#FFFF00">   Outcrossing </font> <font face="Garamond" size="4" color="#FFFFFF"> is when the two parents are totally unrelated. In pedigree animals, this often means where a common ancestor does not occur behind either parent within a four or five generation pedigree. In animals with a small foundation gene pool, this condition is difficult to meet.<o:p> First I will define some terms used by animal breeders. In general I've avoided specialist terms, but you will meet these terms outside of this article.<o:p> </o:p> </font> </b> </span></font></p> <p align="center"><font face="Garamond"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b> <font face="Garamond" size="4" color="#FFFFFF"> <img border="0" src="images/bar080.gif" width="604" height="12"></font> </b> </span></font></p> <p align="left"><font face="Garamond"><img border="0" src="images/cat.bmp"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font size="4" color="#FFFF00"> "Homozygous" </font> <font face="Garamond" size="4" color="#FFFFFF"> means having inherited the same "gene" for a particular trait from both parent e.g. for fur length. Barring random mutation, 100% of the offspring of a homozygous individual will inherit that gene. Inbreeding increases homozygosity by "fixing" a particular trait. Purebred animals display a high degree of homozygosity compared to mixed breeds and random-bred animals. The idea of purebred animals is that they should "breed true". When one purebred is mated with another of the same breed, the offspring will have uniform characteristics and will resemble the parents. <o:p>  </font> </b> </span></font></p> <p align="center"><font face="Garamond"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b> <font face="Garamond" size="4" color="#FFFFFF"> <img border="0" src="images/bar080.gif" width="604" height="12"></font> </b> </span></font></p> <p align="left"><font face="Garamond"><img border="0" src="images/cat.bmp" width="30" height="30"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font size="4" color="#FFFF00">"Heterozygous" </font> <font face="Garamond" size="4" color="#FFFFFF"> means having inherited a different gene for a particular trait from each parent. For example one gene of long fur (recessive) and one gene for short fur (dominant). 50% of a heterozygous individual's offspring will inherit one form and 50% will inherit the other. Carefully controlled "out-crossing" increases heterozygosity for selected traits by introducing new genes into the hybrid offspring.<o:p> </o:p> </font> </b> </span></font></p> <p align="center"><font face="Garamond"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b> <font face="Garamond" size="4" color="#FFFFFF"> <img border="0" src="images/bar080.gif" width="604" height="12"></font> </b> </span></font></p> <p align="left"><font face="Garamond"><img border="0" src="images/cat.bmp" width="30" height="30"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font size="4" color="#FFFF00">"Heterosis" </font> <font face="Garamond" size="4" color="#FFFFFF"> is the scientific term for hybrid vigour. It is possible that there are "bad" genes which produce less vigourous individuals when in the homozygous state because good genes have been bred out along with the undesirable characteristics; theoretically the bad genes could be bred out, but in practice this doesn't seem to happen. The other theory is simply that you simply need to have a mixture of two different genes to get the desired effect as they somehow complement each other; highly inbred animals lack this diversity and have poorer immune systems.<o:p> </o:p> </font> </b> </span></font></p> <p align="center"><font face="Garamond"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b> <font face="Garamond" size="4" color="#FFFFFF"> <img border="0" src="images/bar080.gif" width="604" height="12"></font> </b> </span></font></p> <p align="left"><font face="Garamond"><img border="0" src="images/cat.bmp" width="30" height="30"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font size="4" color="#FFFF00"> "Sex-linked" </font> <font face="Garamond" size="4" color="#FFFFFF"> refers to a trait which is passed on, or determined by, a particular gender. In Abyssinian cats there are several versions of the red colour. One is sex-linked i.e. a male cat only needs one copy of the gene, but a female needs two copies of the gene to produce the red colour. <o:p> </font> </b><font face="Garamond" size="4"> </o:p> </font> </span></font></p> <p align="center"><font face="Garamond"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b> <font face="Garamond" size="4" color="#FFFFFF"> <img border="0" src="images/bar080.gif" width="604" height="12"></font> </b> </span></font></p> <p align="left"><font face="Garamond"><b><span lang="EN-GB" style="mso-ansi-language: EN-GB"><font size="4" color="#FFFF00"> </font></span></b><img border="0" src="images/cat.bmp"><font color="#FFFF00"><b><span lang="EN-GB" style="mso-ansi-language: EN-GB"><font size="4"> NATURAL OCCURRANCE OF INBREEDING</font></span></b><span lang="EN-GB" style="mso-ansi-language: EN-GB"> <font size="4"> <o:p> </o:p> </font> </span></font></font></p> <p><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font face="Garamond" size="4" color="#FFFFFF">This is not to say that inbreeding does not occur naturally. A feral colony which is isolated from other cats, by geographical or other factors, can become very inbred especially if a dominant male mates with his sisters, then with his daughters and grand-daughters. When he is deposed it will most likely be by his own son or grandson which therefore continues the inbreeding. The effect of any deleterious genes becomes noticeable in later generations as the majority of the offspring inherit these genes. Scientists have discovered that cheetahs, even if living in different areas, are genetically very similar. Possibly disease or disaster drastically reduced cheetah numbers in the past creating a genetic bottleneck. All modern day cheetahs may be descended from a single surviving family unit hence their genetic uniformity. <o:p> </o:p> </font> </b> </span></p> <p align="center"><font face="Garamond"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b> <font face="Garamond" size="4" color="#FFFFFF"> <img border="0" src="images/bar080.gif" width="604" height="12"></font> </b> </span></font></p> <p align="left"><font face="Garamond"><img border="0" src="images/cat.bmp"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font size="4" color="#FFFF00"> In the Cheetah,</font> <font face="Garamond" size="4" color="#FFFFFF"> the lack of genetic diversity makes them susceptible to disease since they lack the ability to resist certain viruses. Extreme inbreeding affects their reproductive success with small litter sizes and high mortality rates. Some scientists hope that the appearance of the "King Cheetah", characterised by its blotched markings, means that the Cheetah can develop a healthier gene-pool through mutation (provided man doesn't wipe them out in the meantime). Mankind has contributed to the loss of diversity by sport-hunting cheetahs and reducing the number of available mates. Hunters preferred to shoot unusual specimens (i.e. genetically diverse ones) for the trophy room and this previously included long-haired "woolly cheetahs" and grey/blue cheetahs indicating much greater genetic diversity in the past.<o:p>  </font> </b> </span></font></p> <p><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font face="Garamond" size="4" color="#FFFFFF">Despite the hopes of scientists, some cheetah populations are showing further signs of inbreeding. Confined to ever-smaller areas such as wildlife reserves, the populations have become genetically isolated from each other. In one population there is an increasing frequency of misaligned jaws and kinked tails. Continued inbreeding will reinforce, or fix, these traits. Ultimately, they could reduce the cheetah's hunting effectiveness - the kinked tail will reduce its agility and cornering ability and the misaligned jaws may not be able to hold onto prey. <o:p> </o:p> </font> </b> </span></p> <p align="center"><font face="Garamond"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b> <font face="Garamond" size="4" color="#FFFFFF"> <img border="0" src="images/bar080.gif" width="604" height="12"></font> </b> </span></font></p> <p align="left"><font face="Garamond"><img border="0" src="images/cat.bmp"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font size="4" color="#FFFF00"> The wolf </font> <font face="Garamond" size="4" color="#FFFFFF"> was once widespread throughout North American, but many of the remaining packs are isolated and have become inbred. The isolation/inbreeding problem has become so acute that conservationists have taken wolves from one area and introduced them into a another area to revitalise the gene pool. In some areas, the choice of mates is so reduced that wolves have resorted to mating with domestic dogs - an extreme form of outcrossing called hybridization. A similar situation in Scotland where the Scottish Wildcat mates with domestic cats is threatening to wipe out the wildcat as domestic cat genes become more widespread. These are two cases where outcrossing (following, and followed by, inbreeding) may lead to extinction of a species (analogous to loss of type in domestic breeds). <o:p> </o:p> </font> </b> </span></font></p> <p align="center"><font face="Garamond"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b> <font face="Garamond" size="4" color="#FFFFFF"> <img border="0" src="images/bar080.gif" width="604" height="12"></font> </b> </span></font></p> <p align="left"><font face="Garamond"><img border="0" src="images/cat.bmp"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font size="4" color="#FFFF00"> Another animal </font> <font face="Garamond" size="4" color="#FFFFFF"> suffering from the effects of inbreeding is the Giant Panda. As with the Cheetah, this has led to poor fertility among Pandas and high infant mortality rates. As Panda populations become more isolated from one another (due to humans blocking the routes which Pandas once used to move from one area to another), Pandas have greater difficulty in finding a mate with a different mix of genes and breed less successfully. <o:p> </o:p> </font> </b> </span></font></p> <p align="left"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font face="Garamond" size="4" color="#FFFFFF">It is almost inevitable that the Giant Panda will become extinct even if cloning techniques become available since the gene pool is now probably too impoverished for the species' long term viability. It may, therefore, be considered that all purebred animals will ultimately become unviable through inbreeding and that breeders must work carefully to maintain type while slowing down the detrimental effects of selective breeding. <o:p> </o:p> </font> </b> </span></p> <p align="center"><font face="Garamond"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b> <font face="Garamond" size="4" color="#FFFFFF"> <img border="0" src="images/bar080.gif" width="604" height="12"></font> </b> </span></font></p> <p><font face="Garamond"><img border="0" src="images/cat.bmp" width="30" height="30"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font size="4" color="#FFFF00"> Natural isolation </font> <font face="Garamond" size="4" color="#FFFFFF"> and inbreeding have given rise to domestic cat breeds such as the Manx which developed on an island so that the gene for taillessness became widespread despite the problems associated with it. Apart from the odd cat jumping ship on the Isle of Man, there was little outcrossing and the effect of inbreeding is reflected in smaller-than-average litter sizes (geneticists believe that more Manx kittens than previously thought are reabsorbed due to genetic abnormality), stillbirths and spinal abnormalities which diligent breeders have worked so hard to eliminate. <o:p> </o:p> </font> </b> </span></font></p> <p><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font face="Garamond" size="4" color="#FFFFFF">As mentioned, some feral colonies become highly inbred due to being isolated from other cats (e.g. on a remote farm) or because other potential mates in the area have been neutered, removing them from the gene pool. Most cat workers dealing with ferals have encountered some of the effects of inbreeding. Within such colonies there may be a higher than average occurrence of certain traits. Some are not serious e.g. a predominance of calico pattern cats. Other inherited traits which can be found in greater than average numbers in inbred colonies include polydactyly (the most extreme case reported so far being an American cat with 9 toes on each foot), dwarfism (although dwarf female cats can have problems when try to deliver kittens due to the kittens' head size), other structural deformities or a predisposition to certain inheritable conditions. <o:p> </o:p> </font> </b> </span></p> <p><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font face="Garamond" size="4" color="#FFFFFF">The ultimate result of continued inbreeding is terminal lack of vigour and probable extinction as the gene pool contracts, fertility decreases, abnormalities increase and mortality rates rise. On the other hand, too much outcrossing will cause loss of type and therefore the loss of a distinct breed.<o:p> </font> </b><font face="Garamond" size="4" color="#FFFFFF"> </o:p> </font> </span></p> <p align="center"><font face="Garamond"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b> <font face="Garamond" size="4" color="#FFFFFF"> <img border="0" src="images/bar080.gif" width="604" height="12"></font> </b> </span></font></p> <p><font face="Garamond"><img border="0" src="images/cat.bmp" width="30" height="30"><font color="#FFFF00"><b><font size="4"> SELECTIVE BREEDING</font></b> <font face="Garamond" size="4"> <o:p> </font> </font><font color="#FFFFFF" face="Garamond" size="4"> </o:p> </font></font></p> <p><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font face="Garamond" size="4" color="#FFFFFF">Artificial isolation (selective breeding) produces a similar effect. When creating a new breed from an attractive mutation, the gene pool is initially necessarily small with frequent matings between related cats. Some breeds which resulted from spontaneous mutation have been fraught with problems such as spasticity (cerebellar hypoplasia) in Devon Rexes, skeletal problems in Scottish Folds and the effects of a semi-lethal gene (aka deferred lethal gene) in Manxes and the lethal gene in Ojos Azules. Problems such as hip dysplasia and patella luxation are more common in certain breeds and breeding lines than in others, suggesting that past inbreeding has distributed the faulty genes. Selecting suitable outcrosses can reintroduce healthy genes, which might otherwise be lost, without adversely affecting type. <o:p> </o:p> </font> </b> </span></p> <p><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font face="Garamond" size="4" color="#FFFFFF">An example of a lethal gene which determines a breed trait is the blue-eyed Ojos Azules. The gene is lethal in the homozygous form causing stillbirth, cranial deformities, white fur and a small curled tail. In the heterozygous form, the Ojos Azules are blue eyed non-white cats. Breeders must therefore breed blue-eyed cats (heterozygous) to non-blue-eyed cats (lacking the gene for the eye colour, but having the conformation) in order to get a roughly 50/50 split of blue-eyed and non-blue-eyed kittens while avoiding deformed dead kittens.<o:p> </o:p> </font> </b> </span></p> <p><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font face="Garamond" size="4" color="#FFFFFF">The more that inbreeding is used to get rid of undesirable traits or to fix a desirable trait, the more likely it is that individuals will also inherit the same set of genes for the immune system from both parents, and be born with less vigourous immune systems. The immune system problem is compounded over successive generations as the animals become genetically more uniform (like the cheetah). According to one theory, immunodeficiency may be caused by a simple lack of heterozygosity in the genes that control the immune system. This is why random-bred cats are generally so robust.<o:p> </o:p> </font> </b> </span></p> <p align="center"><font face="Garamond"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b> <font face="Garamond" size="4" color="#FFFFFF"> <img border="0" src="images/bar080.gif" width="604" height="12"></font> </b> </span></font></p> <p><font face="Garamond"><img border="0" src="images/cat.bmp" width="30" height="30"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font size="4" color="#FFFF00"> Zoos engaged in captive breeding programs </font> <font face="Garamond" size="4" color="#FFFFFF"> are aware of this need to outcross their own stock to animals from other collections. Captive populations are at risk from inbreeding since relatively few mates are available to the animals, hence zoos must borrow animals from each other in order to maintain the genetic diversity of offspring. In sheep, centuries of selective breeding to improve the quality of wool has caused an important trait to be lost. Ancestral sheep could breed more than once per year. Modern sheep breed once per year. Only recently has the importance of the lost gene been realised (i.e. to increase meat yield), but to reintroduce it from primitive sheep would reduce other qualities selectively bred for over centuries.<o:p> </o:p> </font> </b> </span></font></p> <p align="center"><font face="Garamond"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b> <font face="Garamond" size="4" color="#FFFFFF"> <img border="0" src="images/bar080.gif" width="604" height="12"></font> </b> </span></font></p> <p><font face="Garamond"><img border="0" src="images/cat.bmp" width="30" height="30"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font size="4" color="#FFFF00"> Most laboratory mice </font> <font face="Garamond" size="4" color="#FFFFFF"> are becoming so highly inbred that they would probably not survive outside of a sterile laboratory due to poor immune systems (they are generally killed before this becomes a problem in the laboratory situation) and some strains become extinct due to reproductive failure. Many are selectively bred to exhibit defects which will kill them.<o:p> </o:p> </font> </b> </span></font></p> <p><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font face="Garamond" size="4" color="#FFFFFF">Inbreeding holds problems for anyone involved in animal husbandry - from canary fanciers to farmers. Early Turkish Vans were reported to be temperamental, a problem apparently rectified by the importation of new stock. Attempts to change the appearance of Burmese cats in America to produce a cat with a rounder head resulted in cats with congenital problems. Siamese cats have become progressively finer-boned as breeders strive to emphasise the foreign look, resulting in frailer cats in some breeding lines. <o:p> </o:p> </font> </b> </span></p> <p align="center"><font face="Garamond"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b> <font face="Garamond" size="4" color="#FFFFFF"> <img border="0" src="images/bar080.gif" width="604" height="12"></font> </b> </span></font></p> <p><font face="Garamond"><img border="0" src="images/cat.bmp" width="30" height="30"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font size="4" color="#FFFF00"> In the dog world, </font> <font face="Garamond" size="4" color="#FFFFFF"> a number of breeds now exhibit hereditary faults due to the over-use of a particularly "typey" stud which was later found to carry a gene detrimental to health. By the time the problems came to light they had already become widespread as the stud had been extensively used to "improve" the breed. In the past some breeds were crossed with dogs from different breeds in order to improve type, but nowadays the emphasis is on preserving breed purity and avoiding mongrels. <o:p> </o:p> </font> </b> </span></font></p> <p><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font face="Garamond" size="4" color="#FFFFFF">Those involved with minority breeds (rare breeds) of livestock face a dilemma as they try to balance purity against the risk of genetic conformity. Enthusiasts preserve minority breeds because their genes may prove useful to farmers in the future, but at the same time the low numbers of the breed involved means that it runs the risk of becoming unhealthily inbred. When trying to bring a breed back from the point of extinction, the introduction of "new blood" through crossing with an unrelated breed is usually a last resort because it can change the very character of the breed being preserved (as noted by cat fanciers when Russian Blues were crossed to Blue Point Siamese after World War II). In livestock, successive generations of progeny must be bred back to a purebred ancestor for 6 - 8 generations before the offspring can be considered purebred themselves. <o:p> </o:p> </font> </b> </span></p> <p align="center"><font face="Garamond"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b> <font face="Garamond" size="4" color="#FFFFFF"> <img border="0" src="images/bar080.gif" width="604" height="12"></font> </b> </span></font></p> <p><font face="Garamond"><img border="0" src="images/cat.bmp" width="30" height="30"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font size="4" color="#FFFF00"> In the cat fancy, </font> <font face="Garamond" size="4" color="#FFFFFF"> breed purity is equally desirable, but can be taken to ridiculous lengths. Some fancies will not recognise "hybrid" breeds such as the Tonkinese because it produces variants (yet Manxes are recognised and also produce variants). Breeds which cannot produce some degree of variability among their offspring risk finding themselves in the same predicament as Cheetahs and Giant Pandas. Such fancies have lost sight of the fact that they are registering "pedigree" cats, not "pure-bred" cats, especially since they may recognise breeds which require occasional outcrossing to maintain type! <o:p> </o:p> </font> </b> </span></font></p> <p><font face="Garamond"><img border="0" src="images/cat.bmp" width="30" height="30"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font size="4" color="#FFFF00"> The breed purity debate </font> <font face="Garamond" size="4" color="#FFFFFF"> goes along these lines: should a breed be based on genotype (what genes it inherited) or phenotype (appearance, despite an out-cross four generations ago) A Tabby-point Siamese is phenotypically Siamese, but because the tabby patter was introduced from non-Siamese cats, genotype-followers consider it "not Siamese" and are worried it will pollute their purebred breeding lines. In some registries, Exotic Longhairs are identical to Persians, but may not be bred with Persians. Likewise, some registries do not allow chocolate or lilac Persians to be classed as Persians because the colours were introduced from Siamese cats (via the Himalayan breed) umpteen generations ago and are therefore "tainted". Those "tainted" genes may be bundled with whole lot of healthy genes; by not outcrossing "purebreds" to "tainted" cats, the opportunity to increase the heterozygosity of the immune system is lost.<o:p> </o:p> </font> </b> </span></font></p> <p align="center"><font face="Garamond"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b> <font face="Garamond" size="4" color="#FFFFFF"> <img border="0" src="images/bar080.gif" width="604" height="12"></font> </b> </span></font></p> <p><font face="Garamond"><img border="0" src="images/cat.bmp" width="30" height="30"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font size="4" color="#FFFF00"> One formula to reduce inbreeding </font> <font face="Garamond" size="4" color="#FFFFFF"> and slow down the loss of vigour is to line-breed for 2-3 generation and then out-cross to an unrelated line (or occasionally another breed) to get back hybrid vigour and genetic diversity. However with the emphasis on breeding for type and competitiveness on the showbench (and when making a sale), the typey studs get used more and more often and there is less and less chance of finding a truly unrelated line. <o:p> </o:p> </font> </b> </span></font></p> <p><b><span style="mso-ansi-language: EN-GB" lang="EN-GB"><span style="mso-ansi-language: EN-GB"><font face="Garamond" size="4" color="#FFFFFF">See </font> </span><font face="Garamond" size="4">The Pros and Cons of Cloning<span style="mso-ansi-language: EN-GB"> for further discussion on inbreeding hazards should cloning of typey animals become permissible.<o:p> </span></font></span></b><font color="#FFFFFF" face="Garamond"><span lang="EN-GB" style="mso-ansi-language: EN-GB"> <font size="4"> </o:p> </font> </span></font></p> <p align="center"><font face="Garamond"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b> <font face="Garamond" size="4" color="#FFFFFF"> <img border="0" src="images/bar080.gif" width="604" height="12"></font> </b> </span></font></p> <p><font face="Garamond"><img border="0" src="images/cat.bmp" width="30" height="30"><b><span lang="EN-GB" style="mso-ansi-language: EN-GB"><font size="4" color="#FFFF00"> IMPLICATIONS OF INBREEDING FOR THE CAT BREEDER </font> <font face="Garamond" size="4" color="#FFFFFF"> <o:p> </o:p> </font> </span></b></font></p> <p><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font face="Garamond" size="4" color="#FFFFFF">Most cat breeders are well aware of potential pitfalls associated with inbreeding although it is tempting for a novice to continue to use one or two closely related lines in order to preserve or improve type. Breeding to an unrelated line of the same breed (where possible) or outcrossing to another breed (where permissible) can ensure vigour. Despite the risk of importing a few undesirable traits which may take a while to breed out, outcrossing can prevent a breed from stagnating by introducing fresh genes into the gene pool. It is important to outcross to a variety of different cats, considered to be genetically "sound" (do any of their previous offspring exhibit undesirable traits?) and preferably not closely related to each other. Outcrossing is made difficult by the amount of inbreeding in previous generations - it becomes hard to find cats which are not related, sometimes several times over.<o:p> </o:p> </font> </b> </span></p> <p align="center"><font face="Garamond"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b> <font face="Garamond" size="4" color="#FFFFFF"> <img border="0" src="images/bar080.gif" width="604" height="12"></font> </b> </span></font></p> <p><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font face="Garamond" size="4" color="#FFFFFF">How can you tell if a breed or line is becoming too closely inbred? One sign is that of reduced fertility in either males or females. Male Cheetahs are known to have a low fertility rate. Failure to conceive, small litter sizes and high kitten mortality on a regular basis indicates that the cats may be becoming too closely related. The loss of a large proportion of cats to one disease (e.g. enteritis) indicates that the cats are losing/have lost immune system diversity. If 50% of individuals in a breeding program die of a simple infection, there is cause for concern. <o:p> </o:p> </font> </b> </span></p> <p><font face="Garamond"><img border="0" src="images/cat.bmp" width="30" height="30"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font size="4" color="#FFFF00"> Highly inbred cats </font> <font face="Garamond" size="4" color="#FFFFFF"> also display abnormalities on a regular basis as "bad" genes become more widespread. These abnormalities can be simple undesirable characteristics such as misaligned jaws (poor bite) or more serious deformities. Sometimes a fault can be traced to a single stud or queen which should be removed from the breeding program even if it does exhibit exceptional type. If its previous progeny are already breeding it's tempting to think "Pandora's Box is already open and the damage done so I'll turn a blind eye". Ignoring the fault and continuing to breed from the cat will cause the faulty genes to become even more widespread in the breed, causing problems later on if its descendants are bred together. <o:p> </o:p> </font> </b> </span></font></p> <p align="center"><font face="Garamond"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b> <font face="Garamond" size="4" color="#FFFFFF"> <img border="0" src="images/bar080.gif" width="604" height="12"></font> </b> </span></font></p> <p><font face="Garamond"><img border="0" src="images/cat.bmp" width="30" height="30"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font size="4" color="#FFFF00"> One breed which was almost lost </font> <font face="Garamond" size="4" color="#FFFFFF"> because of inbreeding is the American Bobtail. Inexperienced breeders tried to produce a colourpoint bobtailed cat with white boots and white blaze and which bred true for type and colour, but only succeeded in producing unhealthy inbred cats with poor temperaments. A later breeder had to outcross the small fine-boned cats she took on, at the same time abandoning the rules governing colour and pattern, in order to reproduce the large, robust cats required by the standard and get the breed on a sound genetic footing. <o:p> </font> </b><font face="Garamond" size="4"> </o:p> </font> </span></font></p> <div align="center"> <table class="MsoNormalTable" border="1" cellspacing="1" cellpadding="0" width="685" style="width:513.75pt;mso-cellspacing:.7pt;mso-padding-alt:5.25pt 5.25pt 5.25pt 5.25pt"> <tr> <td width="23%" valign="top" style="width:23.0%;padding:5.25pt 5.25pt 5.25pt 5.25pt"> <p class="MsoNormal"><b><span style="mso-ansi-language: EN-GB" lang="EN-GB"><font color="#FFFFFF" face="Garamond" size="4"> <o:p> </o:p> </font></span></b></p> </td> <td width="39%" valign="top" style="width:39.0%;padding:5.25pt 5.25pt 5.25pt 5.25pt"> <p align="center" style="text-align:center"><b><span style="mso-ansi-language: EN-GB" lang="EN-GB"><span style="mso-ansi-language: EN-GB"><font size="4">PROS</font></span><font color="#FFFFFF" face="Garamond"><span lang="EN-GB" style="mso-ansi-language:EN-GB"><font size="4"><o:p> </o:p> </font> </span></font></span></b></p> </td> <td width="39%" valign="top" style="width:39.0%;padding:5.25pt 5.25pt 5.25pt 5.25pt"> <p align="center" style="text-align:center"><b><span style="mso-ansi-language: EN-GB" lang="EN-GB"><span style="mso-ansi-language: EN-GB"><font size="4">CONS</font></span><font color="#FFFFFF" face="Garamond"><span lang="EN-GB" style="mso-ansi-language:EN-GB"><font size="4"><o:p> </o:p> </font> </span></font></span></b></p> </td> </tr> <tr> <td width="23%" valign="top" style="width:23.0%;padding:5.25pt 5.25pt 5.25pt 5.25pt"> <p><span style="mso-ansi-language: EN-GB" lang="EN-GB"><b><span style="mso-ansi-language: EN-GB"><font face="Garamond" size="4" color="#FFFFFF">INBREEDING<br> (Mating of closely related individuals)</font></span><font color="#FFFFFF" face="Garamond"><span lang="EN-GB" style="mso-ansi-language:EN-GB"><font size="4"><o:p> </o:p> </font> </span></font></b></span></p> </td> <td width="39%" valign="top" style="width:39.0%;padding:5.25pt 5.25pt 5.25pt 5.25pt"> <p><b><span style="mso-ansi-language: EN-GB" lang="EN-GB"><span style="mso-ansi-language: EN-GB"><font face="Garamond" size="4" color="#FFFFFF">Produces uniform or predictable offspring.<br> Hidden (recessive) genes show up and can be eliminated.<br> Individuals will "breed true" and are "pure."<br> Doubles up good genes.<br> Eliminates unwanted traits.</font></span><font color="#FFFFFF" face="Garamond"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><font size="4"><o:p> </o:p> </font> </span></font></span></b></p> </td> <td width="39%" valign="top" style="width:39.0%;padding:5.25pt 5.25pt 5.25pt 5.25pt"> <p><b><span style="mso-ansi-language: EN-GB" lang="EN-GB"><span style="mso-ansi-language: EN-GB"><font face="Garamond" size="4" color="#FFFFFF">Doubles up on faults and weaknesses.<br> Progressive loss of vigor and immune response.<br> Increased reproductive failures, fewer offspring.<br> Emphasis on appearance means accidental loss of "good" genes for other attributes.<br> Genetically impoverished individuals.</font></span><font color="#FFFFFF" face="Garamond"><span lang="EN-GB" style="mso-ansi-language:EN-GB"><font size="4"><o:p> </o:p> </font> </span></font></span></b></p> </td> </tr> <tr> <td width="23%" valign="top" style="width:23.0%;padding:5.25pt 5.25pt 5.25pt 5.25pt"> <p><b><span style="mso-ansi-language: EN-GB" lang="EN-GB"><span style="mso-ansi-language: EN-GB"><font face="Garamond" size="4" color="#FFFFFF">LINE-BREEDING<br> (Mating of less closely related individuals)</font></span><font color="#FFFFFF" face="Garamond"><span lang="EN-GB" style="mso-ansi-language:EN-GB"><font size="4"><o:p> </o:p> </font> </span></font></span></b></p> </td> <td width="39%" valign="top" style="width:39.0%;padding:5.25pt 5.25pt 5.25pt 5.25pt"> <p><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font face="Garamond" size="4" color="#FFFFFF">Avoid inbreeding of very closely-related cats, but cats are still "pure".<br> Produces uniform or predictable offspring.<br> Slows genetic impoverishment. <o:p> </o:p> </font> </b> </span></p> </td> <td width="39%" valign="top" style="width:39.0%;padding:5.25pt 5.25pt 5.25pt 5.25pt"> <p><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font face="Garamond" size="4" color="#FFFFFF">Require excellent individuals.<br> Does not halt genetic impoverishment, only slows it down. <o:p> </o:p> </font> </b> </span></p> </td> </tr> <tr> <td width="23%" valign="top" style="width:23.0%;padding:5.25pt 5.25pt 5.25pt 5.25pt"> <p><b><span style="mso-ansi-language: EN-GB" lang="EN-GB"><span style="mso-ansi-language: EN-GB"><font face="Garamond" size="4" color="#FFFFFF">OUTCROSSING (Mating of unrelated individuals within the same breed)</font></span><font color="#FFFFFF" face="Garamond"><span lang="EN-GB" style="mso-ansi-language:EN-GB"><font size="4"><o:p> </o:p> </font> </span></font></span></b></p> </td> <td width="39%" valign="top" style="width:39.0%;padding:5.25pt 5.25pt 5.25pt 5.25pt"> <p><b><span style="mso-ansi-language: EN-GB" lang="EN-GB"><span style="mso-ansi-language: EN-GB"><font face="Garamond" size="4" color="#FFFFFF">Brings in new qualities or reintroduces lost qualities.<br> Increases vigor.<br> Cats are still "pure".</font></span><font color="#FFFFFF" face="Garamond"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><font size="4"><o:p> </o:p> </font> </span></font></span></b></p> </td> <td width="39%" valign="top" style="width:39.0%;padding:5.25pt 5.25pt 5.25pt 5.25pt"> <p><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font face="Garamond" size="4" color="#FFFFFF">Less consistency and predictability of offspring.<br> May have to breed out unwanted genes accidentally introduced at same time.<br> May be hard to find individuals which are true outcrosses. <o:p> </o:p> </font> </b> </span></p> </td> </tr> <tr style="mso-yfti-lastrow:yes"> <td width="23%" valign="top" style="width:23.0%;padding:5.25pt 5.25pt 5.25pt 5.25pt"> <p><b><span style="mso-ansi-language: EN-GB" lang="EN-GB"><span style="mso-ansi-language: EN-GB"><font face="Garamond" size="4" color="#FFFFFF">HYBRIDIZATION (Mating of unrelated individuals of different breeds)</font></span><font color="#FFFFFF" face="Garamond"><span lang="EN-GB" style="mso-ansi-language:EN-GB"><font size="4"><o:p> </o:p> </font> </span></font></span></b></p> </td> <td width="39%" valign="top" style="width:39.0%;padding:5.25pt 5.25pt 5.25pt 5.25pt"> <p><b><span style="mso-ansi-language: EN-GB" lang="EN-GB"><span style="mso-ansi-language: EN-GB"><font face="Garamond" size="4" color="#FFFFFF">Brings in new qualities or reintroduces lost qualities.<br> Increases vigor, may improve immune system and reproductive capacity.<br> Introduces totally new traits e.g. color. Fur type.<br> May result in new breeds.<br> The offspring are considered "impure" for many generations.</font></span><font color="#FFFFFF" face="Garamond"><span lang="EN-GB" style="mso-ansi-language:EN-GB"><font size="4"><o:p> </o:p> </font> </span></font></span></b></p> </td> <td width="39%" valign="top" style="width:39.0%;padding:5.25pt 5.25pt 5.25pt 5.25pt"> <p><b><span style="mso-ansi-language: EN-GB" lang="EN-GB"><span style="mso-ansi-language: EN-GB"><font face="Garamond" size="4" color="#FFFFFF">Unpredictable - new traits may not all be desirable.<br> Must choose outcross breed whose qualities complement or match own breed.<br> May take years to eliminate unwanted traits/loss of type.<br> May take years to get consistent offspring.<br> Produces many variants not suitable for use in breeding program.</font></span><font color="#FFFFFF" face="Garamond"><span lang="EN-GB" style="mso-ansi-language:EN-GB"><font size="4"><o:p> </o:p> </font> </span></font></span></b></p> </td> </tr> </table> </div> <p><span lang="EN-GB" style="mso-ansi-language: EN-GB"><font face="Garamond" size="4" color="#FFFFFF"> <o:p> </o:p> </font> </span></p> <p><font face="Garamond"><img border="0" src="images/cat.bmp" width="30" height="30"><b><span style="mso-ansi-language: EN-GB" lang="EN-GB"><font color="#FFFF00"><span style="mso-ansi-language: EN-GB"><font size="4"> CO</font></span><font face="Garamond" size="4"><o:p></font><span style="mso-ansi-language: EN-GB"><font face="Garamond" size="4">NCLUSION</font></span><font face="Garamond" size="4">  </font></font><font color="#FFFFFF" face="Garamond" size="4"></o:p> </font></span></b></font></p> <p><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font face="Garamond" size="4" color="#FFFFFF">Inbreeding is a two-edged sword. On the one hand a certain amount of inbreeding can fix and improve type to produce excellent quality animals. On the other hand, excessive inbreeding can limit the gene pool so that the breed loses vigour. Breeds in the early stages of development are most vulnerable as numbers are small and the cats may be closely related to one another. It is up to the responsible breeder to balance inbreeding against crossings with unrelated cats in order to maintain the overall health of the line or breed concerned.<o:p> </o:p> </font> </b> </span></p> <p align="center"><font face="Garamond"><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b> <font face="Garamond" size="4" color="#FFFFFF"> <img border="0" src="images/bar080.gif" width="604" height="12"></font> </b> </span></font></p> <p><font face="Garamond"><img border="0" src="images/cat.bmp" width="30" height="30"><b><span style="mso-ansi-language: EN-GB"><font color="#FFFF00" size="4"> FOOTNOTE: THE CHEETAH <o:p> </o:p> </font> </span></b></font></p> <p><span lang="EN-GB" style="mso-ansi-language: EN-GB"><b><font face="Garamond" size="4" color="#FFFFFF">In January 2003, India announced plans to clone cheetahs to help restore the Indian sub-continent's now extinct cheetah population. India plan to clone cheetahs from Iran where about 50 Asiatic Cheetahs remain. <o:p> </o:p> </font> </b> </span></p> <p><b><span style="mso-ansi-language: EN-GB" lang="EN-GB"><span style="mso-ansi-language: EN-GB"><font face="Garamond" size="4" color="#FFFFFF">Cloning creates genetically identical individuals. However, cheetahs are already so highly inbred that individuals are already almost genetically identical so the impact of clones on the population will be to increase numbers rather than further decease genetic variation. If it uses the leopard's own egg cells it would introduce the leopard's mitochondrial DNA (the DNA found in an egg cell) into the cheetah population.</font></span><font color="#FFFFFF" face="Garamond"><span style="mso-ansi-language:EN-GB"><font size="4"><o:p>  </font></span></font></span></b></p> <p align="center"><font face="Garamond" size="3"><b><a href="index.html">Home </a>   <a href="english_siamees.htm"> Siamese</a>   <a href="english_okh.htm">Oriental Shorthair</a>    <a href="english_kittens.htm">Kittens</a>   <a href="english_kittens_2.htm"> Kittens 2</a>    <a href="english_geplande_nesten.htm">Planed Nesten</a>    <a href="english_nakomelingen_gregor.htm">Offspring </a>  <a href="english_nieuwe_eigenaren.htm">New Owners </a>   <a href="english_nieuws.htm">News</a>     <a href="english_katers.htm">Studs</a>    <a href="english_katerverblijf.htm">Studhouse</a>    <a href="english_fokdoel.htm">Our  Aim</a>    <a href="english_castraat.htm">Neuters</a>   <a href="english_inteelt.htm">Healthy Breeding</a>   <a href="english_fearbhail_wie_we_zijn.htm">Who we are</a>   <a href="english_otazu.htm">Otazu</a>    <a href="fearbhail_index_adress.htm">Updates</a>    <a href="english_links.htm">Links</a></b></font></p> </body>