Overview

Different experts and authorities provide highly variable opinions on inbreeding and linebreeding.  I have always found it impossible to take many of these people seriously. Unfortunately, my experience has revealed that few people have the innate curiosity that drives them to find out how things actually work.  Inbreeding or linebreeding is not a mathematical pursuit or formula, except where it might be used to predict the possibility of change in a finite, imaginary population, for a quantitative factor (statistics).  It is not, for me, a complex sketch or diagram of related or unrelated matings.  It is not the simple crossing of brother to sister; cock to daughter or hen to son.  It is art.  It is feel.  It is at once instinctual and intuitive.  It is the compelling observations that a breeder makes about his stock's behavior and inheritance over many years. That knowledge and the relatedness of ones birds is so ingrained in a breeder that he can subconsciously pair the birds that have the greatest likelihood of producing the offspring he wants.

As I indicate in the body of this document, inbreeding is not memorizing a standard form and trying to emulate it as so many people try to suggest.  It is not seeking to identify and build on a sport or oddity or at least rarely, as sports or mutations tend to be discontinuous.  The real inbreeder is driven to develop a bird that exhibits desirable qualities, that is singularly identifiable, behaves well and is active and responsive.  More than anything else the inbred bird must display all of the characteristics that the breeder views as critical and desirable.  If in his or her eyes the "new" bird looks good, then it will become a new standard of its own, and others will come to accept it and want it or reject it out-of-hand.

Inbreeding is the simple and aesthetic act of crossing related stock to produce the best. This is accomplished by selecting for those transmissible and desirable properties, that are the province of only a very few outstanding individuals, and ensuring these traits accumulate within the offspring.

The following position is based on my own observations and reading of numerous articles, both pro and con, on inbreeding.  You may not like my position, I guarantee you will not like my generalizations and you may not like my approach and interpretation.  If you do not want to read something that is controversial and intriguing (unfounded to some of you), you may as well stop now.  The anti inbreeder will resent the information and inferences present here-in.  Biologists, Taxonomists and Ornithologists may find it farcical or erroneous, while Evolutionists may say it is so general in its sweep of suggestions and questions that it is unworthy of response or notice.  However it is received, I believe the questions need to be addressed, or the stories of negative long term effects of successful inbreeding will continue, despite being premised on poor results, excessive selection, human morality or misunderstandings, as I explain later.

A personal and descriptive visual explanation of inbreeding excess

To describe excessive species selection in an understandable way, I like to think of an upside down triangle, where the triangle is comprised of a series of minute horizontal lines, much like pixel density, which generates a digital image. Each horizontal line comprises a single variety or breed (one line per breed or variety).

Varieties continue to be distilled, from a diminishing gene pool, until the inverted apex results in a breed that survives or dies based on whatever genes are eventually left at the end of a long, long selection process. Is this the denouement of the species, if indeed so much of the germinal DNA exists above it ?

Even the most adamant anti inbreeder must recognize that selection is a continuous process in wild species and many of the changes (gentic gain or loss) which occur will not be noticed, even by the most meticulous observer:  That's life in the wild.  Variation enables the species to undergo slow or rapid alteration or change to enable adaptation to a shifting environment: thus continuance of the species may be optimized.

Some would suggest that there should be clear or empty lines in a hypothetical triangle, presented as a solid object, as these clear lines would serve to represent or explain evolutionary or inbreeding dead ends.  I would contend that the triangle appears solid, despite full recording of inbreeding and evolutionary dead ends. The number of viable varieties and genetic permutations far outweighing the encountered or unrealized dead-ends, whether natural or artificially selected.

All species have a finite number of genes, that is indisputable.  The question is: how many genetic / phenotypic permutations are viable, given that a theoretical core of genes are essential for vitality, vigor, fertility, fecundity and longevity ?  If we look at a species that reproduces itself, forms a clear phenotypic presence and has normalized variation (around the arithmetic mean) within the population, how does that description differ from a variety or breed ?  A heterozygous individual, as I have come to understand it, merely indicates that a particular gene has been revealed or expressed through some process, and represents substantive enough change to warrant notice.  Remember, this mutation is not added, but revealed from the "normal" genotype, suggesting that the species carries the gene, but that the gene is in a masked, incomplete or recessive form, waiting to be uncovered or used in a survivalist adaptation.

A wild species or population has (requires) a great deal of potential variability present within its genetic make-up, and consequently a potential for numerous spontaneous presentations of discontinuous mutations.  Given that a variety also has a fair amount of variability surrounding the remaining genetic material, it troubles me when people speak of the wild species being heterozygous.  If it was, there should be spontaneous presentation of mutations on a weekly or monthly basis, depending on the population's size.  Other than numbers, how does the varietal genotype differ from the wild stock, and is the wild stock truly heterozygous, or is it simply homozygous for those traits selected by nature which in turn masks other genes as in the breed or variety? How do people balance a defined heterozygous state with continuous variation or variability around a mean, when that very same variability occurs around a defined homozygous type ? Are we becoming too general with our use and application of heterozygous versus dominant types / species  definitions and usage?  If there is considerable variation from and around the population mean, which represents the recognized physical type, don't heterozygosity and homozygosity begin to overlap in meaning ?  Where does heterozygosity end and where does homozygosity begin?  Is a multigenic mutation heterozygous or homozygous for the traits? Are you becoming confused ?  I am.

Given that each line in the triangle represents a variety or selection, there is obviously a transmittal of genes, both good and bad, among each variety trending away from the species type.  After all, in lovebirds, we only really look at the color mutation aspect, although a few breeders may be seeking size, girth or something else.  In the majority of cases many of the factors we seek as breeders are not continuous. This means that the breeder may not be able to achieve a certain color blend or expression, despite the fact that we have seen many color selections and mutations in Budgerigars and Canaries.  It is the discontinuous events like structural mutations that breeders can work with and intensify among the offspring over time.  These mutants are essentially sports exhibiting some small change in form. Identification and breeding success (repeatability or improvement) depends upon the breeder's awareness of, or recognition of slight changes in offspring in his own aviary population.

Compassion & Breeding

Compassion is not something that the successful inbreeder or line breeder can afford and it may well be why so many inbreeders are despised by those who would effect to save every bird.  Furthermore, we repeatedly hear that breeders are selecting based on individual traits versus the population average.  This may or may not be true, although I would tend to believe it:  Breeding best to best is not a good maxim unless the breeder applies it properly.  I think most long-time breeders would admit that there is always a reversion to type (to the average shape and size of the population being selected), and that even following what we call homozygosity (prepotency) in the desired bird, there will still be significant variation within the population's offspring: not variation to the extent experienced in a large population, but individuality and variance in structure, color, internal workings, muscle, beak etc... .  In other words, even homozygous birds exhibit variability around the select "type", just as variation in wild type offspring occurs around the species "type" as discussed in previous paragraphs.

Failure to assess your stock, and merely selecting the best looking bird is a sure way to run into the problems encountered by most novice or curious inbreeders.  The inbreeder needs to work with the population average.  If a good looking individual does indeed prove himself, by all means mate him to your best hens, but if he fails in passing on his traits, replace him with a better bird (a bird that might not look as good, but passes on real benefit to the stock).  Every breeder wants to rush to the finish, but ensuring your birds are prolific, fertile and active is critical to running the race.  Checking the mean population improvement, instead of basing everything on the outstanding individual whose reproductive vitality may be less than desirable, will help to prevent the serious breeder from getting to far ahead of the process and heading full speed into a dead end.

Finally, I agree with many things said on this site, including the one that says it is a simple matter to for those opposed to inbreeding to make general, sweeping comments about the negative side of inbreeding or ignore it.  Unfortunately, it is impossible to dispel these perceptions when no one wants to discuss or educate others about the process and its pros, cons and myths.

Hybridism - a problem among species ?

While I understand the conservation and purity question surrounding this issue, I often have to wonder why we get so upset by the possibility of species crossing.  If species cannot cross, as has been stated on this site many times, there should be no offspring and no fear of pollution of the gene pool.  Therefore, the only concern that can arise is one of fertility among hybrid offspring; either with parental populations or between each other.  If hybrid offspring are fertile, either with one or other of the parental populations or with each other, there must be some undefined relationship between the "species".  If crossing can occur with little trouble and both sexes are fertile, can we really continue to identify the parent populations as separate species, and if we do, are we only basing speciation on phenotypes versus genotypes?  Improved DNA understanding and analysis would suggest we are burying our heads in the sand on this issue and holding to outdated tenants, despite information or results that point to the opposite of what has been and continues to be taught:  Why?

Each gene or set of genes which can be transferred from a different "species",  may enable significant new combinations to occur, within complementary and viable genomes, regardless of our taxonomic designations.  Given the enormity and potential associated with the number of gene interactions and exchanges available through natural pairing or artificial insemination (A.I.), there should be no surprise that breeders run into a number of dead ends, whether working with hybrids or strains.  Usually, failed seminal varieties, hybrids or breeds are selected, not by genes and performance, but by human compassion, which is  thrown into the selection criteria.  Animals that would not survive in nature, are not only saved and nurtured by people, but are encouraged to breed, thereby passing on undesirable gene combinations that can lead to the very problems everyone tries to avoid or attribute to inbreeding.  I don't want to say inbreeders don't have compassion for they do, but they are usually running a business that parallels the livestock industry.  The selection and intensification of blood in a line or hybrid is done because there is an undeniable and quantifiable economic benefit perceived at the end of the day, by the breeder, on top of the joy associated with developing something new.

There are obviously many more cases of natural hybridism being recognized among different avian populations today, than ever before: one of the primary reasons people are more frequently including "hybrid zone" potential in reports.  This implies that hybridism is not simply a concept derived by greedy or unscrupulous inbreeders, but rather a natural event that is successful or unsuccessful, based on chromosomal similarities and natural selection.  I do not believe any of us would complain to loudly if a breeder decided to cross their pallid roseicollis with a turquoise roseicollis or a blue personata with a green personata.  Why is this activity such an acceptable practice, and yet when we look at the word "species" attached to a group of birds showing the same phenotype in the wild (which implicitly suggests that chromosomes are dissimilar) any crossing or offspring production is considered inviable or an aberration. It is neither logical, scientific sound or pragmatic. Simply put, hybridism wouldn't exist if it couldn't happen or if nature had not planned for it somehow.  The benefits to species survival, from hybridism, given the need for rapid change are obvious.  Is the concern simply because we are referencing a known, defined natural form and we have a reluctance to see the form change or lost.

Artificiality is present in everything we do, from the saving of specific species at horrendous costs, to the re-introduction of species in the wane.  Choose any example you like, whether whooping crane, swift fox, black footed ferret, Giant Panda.  The focus is invariably on altering the food ingestion mechanism, the ecological surroundings and other things.  We talk about isolated populations that are inbred and more susceptible to cold weather fluctuations or some other aberrant climatic phenomena.  Why is this susceptibility considered so significant, the population was not selected for these swift and aggressive changes.  Those that die were ill-equipped for the sudden change, others ( the variability about the mean population) were lucky enough to survive.  We focus on species extinction/extirpation and trying to reintroduce them to the wild.  Man has created the selective pressure on these animals as surely as he has changed the face of the world and perhaps weather phenomena.  It is no surprise that we see wild birds adapting and beginning to forage successfully in urban jungles rather than a natural one: that is simply where selection has led.  We try to save a species, when we should be working to stabilize the ecosystem: if we wish to stabilize anything and prevent the inevitable progression of time and change.  Too complex some would say, but is it any less realistic to think that one can save a single "natural" species, where the environment and food source that the species in question was once dependent on has been eliminated by weather phenomena, catastrophe or climactic spikes?  It is the constant variability around the mean that would seem to ensure survival, not the constancy or fixation of a recognized form or type.  Loss of species will continue: don't doubt it.  It is an historic fact and indisputable. It will continue, either at a reduced rate or increased rate depending on global focus.  Does hybridization increase the chances of survival for "species"   My position is that hybridism is a positive activity interaction that strengthens the odds of gene pool survival, regardless of the commonly perceived "type" that may be universally recognized under prevailing steady state pressures, continuously applied by natural selection in a relatively slowly fluctuating environment, and a means to induce rapid change where rapid or catastrophic environmental changes occur.

The logical meta-question that arises is whether lovebird species named today may in fact be varieties of a much larger parental population, for they really appear to represent a homozygous form in their breeding, phenotypic reproduction and breeding.  Are some of the existing lovebird species actually evolutionary dead ends (without hybridization) because of natural over specialization (lilianae and swindenaria), which also threatens species survival in the event of a cataclysmic event ?  Major steps have been made with production in rare species,  but swindenaria is still a relative unknown, while the pure Nyasa tends to die at or during the molt, except, as I understand it, where a cross with other species has occurred in the background.  Is anyone aware of a mutation or physiological change in the pure Nyasa that enables the juvenile to pass through the molt and survive to adulthood?  If so, how does one know the birds are pure? If not, are these species so adapted to their historical territory that they are incapable of surviving in another environment.  How do adults survive and not offspring, and are offspring that die, the progeny of hybrid birds?
 

Pet Peeves and Irritations

I have become very irritated, frustrated and yes, even cynical about always having to hide my use of certain breeding activities because it will hurt or bruise the sensitivities of those who simply breed, buy and sell birds for economic gain, but do not wish to hear, see or be seen to show interest in anything akin to inbreeding. However, these same people are completely at home and even complimentary about linebreeding.  The honest practitioner will tell you they do not really know where inbreeding turns into line breeding or line breeding into inbreeding. It is refreshing to know that so many who do not practice either breeding method and resent inbreeding, are so comfortable with line breeding.  It baffles me that people can act in such a contradictory way. In my experience, inbreeding is the most useful method that we breeders have in the struggle to condense desirable genes in new types, variants or strains.

If inbreeding gets the job done - the breeder should use it.  If it is the best method to concentrate or intensify desirable bloodline (genes) - the breeder should use it.  If it results in a higher percentage of defective or deformed chicks, then the breeder should accept that as the cost for seeking the best in his stock or as a necessary evil in eradicating lethal or congenital recessives - and use it.

Realize, as many have stated on your site's web pages, that the dirt (minimal / maximal deformity) rises to the surface with inbreeding and can be overcome in most cases if managed properly by the breeder.  Inbreeding is the only way to reliably improve your stock, yet the majority seem to live in fear of it.  It is highly unlikely that those reading this article will not own or have inbred birds present in their stock.  Even going outside your own aviary for an "unrelated bird" of the same mutation, means that the bird you find will be a close or distant relation to your own bird.  Certain mutations tend to be highly inbred, initially, so you have acquired / paid for a bird that is most often the result of inbreeding (mutations tend to be recessive to the wild form and color and subsequently a relational aspect exists). It is also important to realize that the discontinuous nature of mutations does not enable the colors to blend well with the wild type, but instead separate out, based on dominant / recessive inheritance.

I might be so bold as to say that hybrid (transmutation) birds are probably more heterozygous than our own birds because of the need to constantly outcross to the best in the receptor species, to ensure the retention of the physical appearance of that species.  This is quite interesting, as it clearly implies that the hybridizer seeks the homozygosity of the color receptor species.  He does not seek a heterozygous genome, but rather a homozygous genome that enables the hybrid bird to be identified as a member of the receptor species (see: My favorite Peeve).

A hybrid species development or evolution tacitly implies the need for significant hybridizing and inbreeding between the parental generation or F1s depending on fertility ranges.  If begun by only a few pairs, a successful population will be highly inbred, despite the prolific nature and expansion of such a seminal group.  Is there a weakness or flaw associated with this process ? Yes, but nature has its own way of changing and selecting for successful species or varieties, that we are still trying to discover.  Whether you feel this is fanciful, or foolish thinking, double-speak, devoid of fact and substance or scientific scrutiny, the questions that ultimately follow are:

1. How different are (homozygous or prepotent) varieties from the (heterozygous) wild type ?
2. If varieties and wild types are identified by external appearance or phenotype, only small changes can have occurred in the variety - TRUE OR FALSE?
3. If varieties have only experienced a few gene changes that impact color and behavior for a different environment (domestication) - how quantitatively different are they from the wild population ?
4. What is the difference between varieties, breeds, sub-species, strains and yes, even the wild population?
5. If inbred varieties are to succumb to inbreeding depression and loss of vigor, why is this not also true for sub-species and even the primary population, although admittedly the same effect would take much longer because of the larger population - However, even this is premised on a belief that the wild bird is more heterozygous than the variety -  I have read this in report after report, but have seen no mitrochondrial DNA evidence that would substantiate a substantive or significant statistical alteration in DNA chains among wild type species or their sub-species, let alone varieties or breeds.  What level of DNA  or genetic change is required to come to the conclusion that inbreeding leads to a path of eventual destruction ? What time frame are we talking about ?

Most people want to buy the pretty birdie or the colorful parrot in the pet cage  They smile and want their picture taken with a Macaw or Cockatoo. The children want the pretty budgie to hold still on their finger while they are photographed with it.  What is similar or shared between all of these birds ? All of them are inbred to some extent.  Some will say it is taming, training, treats and care that make them such pliant and wonderful pets.  Show me one wild parrot that will respond to strangers the way these "pets" do.  They are inbred, it is not simply handling or TLC, their whole response mechanism and behavior has been undermined or subverted by treats or other training devices.  Oh, it may be that the birds are not genetically inbred, but these birds have been selected for docility and lethargy, not for natural fire, aggressiveness, shyness or vitality.  The average bird lover would be shocked by the difference in behavior and needs of a wild parrot versus a domestic one, so let's take the blinders off for a moment and see that cage birds are usually either inbred or behaviorally altered to some degree.  It can be no other way, given the human desire to see or own new or unusual mutations, crosses or hybrids (non aggressive ones): birds that are calm and unflappable.

The reality is that the pairing population potential in cities or towns tends to be fairly limited when seeking partners for your bird.  If the bird is a combination color, the chances of inbreeding increase.  Yes, people can go and buy birds from a long way off, but depending on the extent of breeding and bird availability, the breeder is going to run into terrific expense and some uncertainty as to the relatedness of purchased and owned birds.  In small populations, inbreeding is inescapable.  It may be a milder form of inbreeding, but inbreeding nonetheless.  Can we really avoid it and do we want to ?

I'll go one step further here and say that inbreeding is a necessary mechanism for improving stock quality, not simply a good or an alternative mechanism, but an excellent one for the exhibition breeder.  There, I have said it, inbreeding is good!  And let any of you argue who may.  Good inbreeding will produce birds that are at least as good as the parents and in many cases better.  We breeders have been hijacked by a sense of moral prudishness with our birds, and by those who continue to advocate against inbreeding while they purchase or demand access to the results.  Those that are not courageous enough to take up the torch of inbreeding will never attain the ultimate breeding pinnacle, the desire of every serious breeder:  A strain of one's own and a bird whose conformation, color, vigor and fertility set it apart as a highly desirable acquisition (there is no escaping the economic compensation that can accompany a desirable mutation or variety).

 There are many who will advocate against inbreeding and state that they have never inbred their birds.  If they have never inbred their birds, I for one must state that they are not really breeders, but simply propagators of a mutation or species.  How do people who have never experienced the success and challenges associated with inbreeding form a knowledgeable position against it ?  From reading stories about fewer eggs, deformed chicks and infertility ?

If, a breeder has never experienced dead-in-shell, infertility, dead chicks, and either mild or severe congenital defects, I for one cannot say what he or she has been doing.  Inevitably, with many years of breeding, the breeder will experience these heartbreaks in the nest, over and over again, despite efforts to outcross his birds.   Inbreeding shortens the time frame for these losses, with correct breeding, and will reward the breeder with healthier stock and birds that are almost identical in size, color, and reproductive success. Are their immune systems compromised by the loss of congenital defect genes, or the unmasking of these lethal or troublesome recessives.  I don't know, but their very existence is a concern in any stock.  How much immunity is lost versus lives saved because of the extraction of a lethal gene or debilitating congenital defect ?

Myth,  Fact or Simply Unknown

• Agapornids are highly inbred.   This statement is a complete fallacy as far as I have been able to determine.  Agapornis is comprised (taxonomically) of 9 separate and distinct species.  When we compare the parrot world to the dog world, we quickly see how very far behind we are in breed or varietal development.  Parrot owners and breeders tend to focus on color and not novelty or specialty varieties.  It only takes a moment to look at all of the canary, pigeon and chicken varieties and breeds that abound as a result of careful or sometimes serendipitous crossings.  The budgerigar fancy has the Australian and English varieties and the feather-duster (some breeders have tried to stabilize, but as far as I am aware there has been no luck to date).  Feather-dusters die within weeks of getting their feathers.

The growing fear and concern around inbreeding appears based on decades of selection and intensive breeding in livestock, canine and feline species.  Breeds and varieties in those species have been established through intensive inbreeding, careful selection, testing and clear objectives.  The selection has been very important to food production and delivered cost, and we have all benefited from that work.  However, problems have recently arisen because of the continued use of a single sire in line breeding and the later realization that the sire carried a lethal or debilitating recessive, which was never identified or eradicated.  Few if any animals come without these inherent genetic problems.  The identification of these problematic genes has led to a resurgence of fear and concern around excessive inbreeding and stock viability based on existing lines of animals and these hidden genes.  While the issue and concern is obviously serious, there are probably enough animals to see the stock clear of the problem after careful analysis, testing and back crosses to the clean sire, although I am only guessing at this, and basing it on simple recessive inheritance mechanisms.
 
Agapornis are, if anything, in the seminal stages of breed development.  We certainly have color mutations, but will we be challenged to any more than that until such time as there are a number of inbred lines or a few sports arise that have aesthetic appeal and can be bred for.  Inbreeding or hybridizing of agapornids in domestication, if premised on the number of breeds in other species, has not even begun. It has barely scratched the surface, and like the canary or pigeon fancy has the potential for numerous breed developments: perhaps like the longfeather, but even this one not for long if it is simply mixed in randomly with the various lovebird color mutations and not maintained.  Inbreeders and hybridizers should be able to educate themselves regarding the best processes and mechanisms to prevent those pitfalls and traps that earlier inbreeders and hybridizers have fallen into in their specific species.  If we cannot learn to accept advice and direction, and educate ourselves once more, based on what has transpired elsewhere, we are bound to repeat the loss of life, congenital aberrations and errors in  relationship and methodologies.

• Inbreeding leads to smaller nests, lack of vigor and poor immunity.  Another statement that leaves me quite perplexed. I certainly understand how inbreeding can be perceived as leading to all of the identified problems, but surely it is not inevitable: in fact, far from it if inbreeding is practiced properly.  We know that inbreeding is a tool that can be applied successfully to maintain fertility, egg production and health, while seeking to concentrate the desirable "phenotypic" genes.  Inbreeding cannot create something that is not there, but it can maintain and perhaps improve certain factors.  We have some very well known, established inbred herds (not parrots) that have been selected for a very long time.  When did inbreeding issues with herd sires develop and was it because of a change in herd management or inbreeder, or a departure from past practices.  How can a stable inbred herd suddenly run into problems with the utilization of a herd bull or sire in a linebreeding scheme, where the system has worked so successfully in the past (PROS AND CONS OF INBREEDING: Copyright Sara Hartwell 1996, 2001, 2003: (http://www.messybeast.com/inbreed.htm).  The only reasonable answer, where a sire is suddenly found to have a hidden genetic defect that has been passed on among the herd, is that herd management has changed.  Why does poor immunity have to be a necessary evil of proper inbreeding.  An initial phenotypic separation from the wild stock, does not imply immune deficiency.  After all, if we look at other species breeds, I would not be surprised to find that those breeds closest to the original stock lost very little if any immunity, particularly if the substantive inbreeding changes were in coat color or fertility.  Obviously, color breeding does not require a huge shift towards a homozygous gene set.  Certainly, as breeds splinter further and further from each other and the foundation stock,  the gene pool will shrink, and there will be more critical issues, but that would seem to be founded on a question of how many breeds a genome may safely be diversified into.  Given the variety of breeds in a number of species, is it unusual or surprising that a number of congenital defects exist among a genome and occasionally come to the surface?  Simply put, I do not understand the mathematics or the conclusion drawn with regard to inevitable deterioration of inbred stock, unless maintenance is thrown to the wind and additional factors are pursued in an otherwise established and stable line.

• Mathematical formula suggesting greater negative impact from inbreeding than previously thought.  I came across this interesting position on inbreeding on The Cat Resources Archive (PROS AND CONS OF INBREEDING: Copyright Sara Hartwell 1996, 2001, 2003: (http://www.messybeast.com/inbreed.htm), an excellent site on inbreeding in cats, although I do not agree with all of the inbreeding statements.  As I have said in this document, I ascribe to the understanding that a finite population may indeed be mathematically assessed for mutational and other inbreeding probabilities.  I mention here, Mr. Roy Silson's Book: "Additive Genes in Evolution and Selection", which has become my bible on inbreeding computations.  Having read this book, I read the Genomics piece in the Cat Resource Archive with great interest, as microsatellite homozygosity or internal relatedness of positive "+" or negative "-" satellite markers may enable one to monitor or physically assess the extent or degree of inbreeding within wild populations.  Is this a modified phylogenetic mitrochondrial DNA analyses ?  At any rate, Mr. Silson suggests, if I have interpreted it correctly, that a cousin by cousin mating is potentially the best "distance" mating available in terms of controlling the Coefficient of Inbreeding, while at the same time generating the greatest potential for change.  If the greatest variability occurs at a cousin / cousin mating level, it  would not be surprising that there would be as much opportunity for beneficial improvement at this stage,  as there would be for the fixing of detrimental genes, which could inevitably lead towards inbreeding depression.  As with all inbreeding, the result is highly dependent on the experience and knowledge of the successful inbreeder.  It would be highly unlikely for a novice inbreeder to escape the high probability for inbreeding depression, where a lack of knowledge is compounded by excitement and an eagerness to inbreed.  Inbreeding success is subsequently highly correlated to a breeder's knowledge and skill, and the application of that skill.

• Successful breeders, not buyers, have a history of inbreeding success to emulate.  Names such as Davenport; Wreidt; Wright and Armour conjure a world of opportunity and change grounded in good science, observation and meticulous record keeping.  These names are famous in a variety of livestock areas as pre-eminent inbreeding or linebreeding supporters.  People who charged hell with a bucket of water and succeeded.  Not only did they succeed in their efforts to develop or improve lines of animals, but have been recorded as doing such or were confident enough to record their own experiences, thoughts and opinions. People now question the success of such activity as the use of an alpha dog, dominant cock or herd bull as a founding sire for a new line, as inherited defects may only become apparent after many sire / daughter matings.  While this is true, it is simply another significant element to be aware of in the selection of your foundation animals.  few will say that inbreeding happens quickly or is a quick goal to an end.  Inbreeding is not for novices, it requires a meticulous recording system, knowledge of your animals inheritance, fantastic luck, rapid identification of problems, the strength to dispose of (cull) animals that do not come up to expectation or simply have a weak constitution or appearance - same approach as Nature, and clear objectives or strengths you want in your birds: not something that is often followed in the pursuit of developing exhibition birds.  It is also important to remember that genetic inheritance and phenotype are not analogous.  A fantastic looking bird, may no be prepotent and able to pass on his genes, where a slightly less appealing bird may be able to pass on all good properties evinced.

• Does inbreeding reduce the gene pool.  I have heard people repeat this belief many times, and have also read it in breeding reports.  Again, I don't know what the answer is, but I thought I would provide the following.  In my opinion, inbreeding does impact the gene pool (whether that reduction is significant or not is another question.  Whether genes are lost or masked is another question - I presume lost, but I don't know).  However, is that gene loss necessarily a bad thing ?  In many ways the gene pool is altered within a decade of capturing wild stock and "acclimating" offspring to domestication.  The original birds will not have changed, but we do know that each new generation of offspring will usually be "selected" for certain traits, that the breeder may not consciously know they are selecting for.  What really gets me agitated is the suggestion that a mutational event or inbreeding of a certain color variety might substantively reduce the gene pool, and the same is said for hybridization of species.  Can someone please explain this to me in an understandable fashion ?   Supposedly, the hybridizer is wasting time and energy by in breeding or hybridizing birds, which might otherwise be producing more heterozygous wild type birds.  I am so sorry, but I cannot accept this type of argument.  We have no idea what the percentage of mutational events, alterations, deaths or congenital defects might be in a wild population.  How can a substantive gene reduction position be drawn ?  If it is a theory, OK, explain the position. Just because we cannot see problems in the wild, is no reason to suppose that in breeders do something evil, or are the causal factor in generating new and horrendous congenital diseases, viruses or illness.  these are merely resident within the birds genome and sometimes become uncovered in the pursuit of certain colors.  I believe that the mutational events and fixing of the mutation by inbreeding actually helps to identify weaknesses that may be attributed to specific inheritance or gene patterns, i.e.: blindness in excessive lutino crosses, where the gene is present or is triggered by some small alteration in the in breeder's aviary or in an aviary other than the in breeders.

• My favorite Peeve :  I have read pros and cons surrounding inbreeding for many years now and the underlying irony in it all is that the reference to inbreeding always returns to the wild populations and the fact that inbreeding threatens the gene pool.  That the pursuit of homozygous or prepotent animals in domestication translates into birds with increased: immune deficiencies; disease susceptibility; sterility; infertility; deformities and deaths.  What these people seem to fail to realize is that wild populations must be homozygous or prepotent in order to produce offspring of like kind. Yes, it may be a heterozygous population, but the outward evidence or phenotype enables us to spot a bird and say: "That is Agapornis roseicollis roseicollis and not Agapornis personata".  The fact that we can visually define species, and that they are not all different suggests that selection has been going on for some time and that the birds we see today are the result of some form of controlled or selective breeding, over time, that has led to their outward appearance or type.  Those opposed to inbreeding bring up the likelihood of catastrophic weather events or a plague that could destroy domestic inbred varieties.  Nobody is saying otherwise, but there is an equally high potential for a lot of wild animals to be killed in catastrophic natural phenomena.  If a bird is developed for a certain niche, such as exhibition, it would not be a surprise to see it suffer and die if released in the wild, where food and water were short, its feather consistency was not in keeping with natural or wild survival parameters and behavioral response mechanisms were dulled by captivity.  If we extend the timeline out far enough, we hear the fears of those who believe that in bred varieties are facing annihilation from selection.  If the genome is homozygous enough, inbreeding depression will occur.  However, true this may be, we can only assume that the same thing will occur in the wild, where "typey" species (homozygous for the characteristics that we use to define differences and species) will also exhaust their gene pool, which will in turn lead to extirpation.  How long will this take ? a long, long time if cheetahs and their ability to survive is any indication.   The interesting question is whether inbreeding, hybridization or splitting and re-joining of "species" is beneficial in prolonging, delaying or generating new and adaptable species.  No matter how many birds we might believe there to be in the wild, it is important to remember that "species" are finite populations and the likelihood and incidence of inbreeding and hybridizing will increase as populations dwindle.

• I cannot comment on hybrid to species evolution, but it is a fascinating concept to consider and when all of the facts are open for review, it is certainly a persuasive and intriguing position.  These pages are the first place I have seen someone build on and increase the trickle down effect of such an occurrence.

• Maintaining purity of existing studs and wild stock. Many aviculturalists and I suppose other animal breeders seem to focus on the purity of wild stock and the necessity for keeping these populations untainted by other species, varieties or hybrids.  Unfortunately, like any "purebred" animal, the pure breed is going to run into trouble when the inbreeding coefficient increases as a result of having no unrelated animal with which to mate.  The great irony here is the fact that anti-in breeders will talk about the necessity for maintaining pure studs and wild populations, and then go on to talk about the heterozygous nature of wild stock and its ability to withstand disease, infection and strange weather events (I have noted this position on  your pages as well).  My simple questions: Are we talking about wild heterozygous or homozygous populations ? Can they be both ?  Are breeders simply turning to any excuse they can to prevent in breeding from a purely human moral perspective.  We know that wild populations have been isolated, which has led to inbreeding and some apparently disastrous results, we still don't know if these populations will find a way out of their quandary or disappear. We also know that many species have active hybrid zones and that taxonomists have reviewed relationships and definitions because of unexplainable occurrences  such as two different species mating and producing fertile offspring with human intervention (Artificial Insemination): An impossibility based on the strictest definition of species.  Birds are supposed to have evolved from dinosaurs so is it any surprise that many of the birds we see today may have similar genetic foundations, particularly those identified as species and sub-species.  How close are those species ?  If indeed a simple physical change in the sex chromosome can lead to incompatibility with birds of the originating species, but enables fertile crossing with a similarly altered bird, the only difference is a physical one.  The birds are otherwise genetically similar.  A reversal of this same chromosomal aberration in an offspring of the newly established variety (sub-species ?) enables these reversal birds in the unique population to cross back into the original or originating population.  Is this a pollution of "other species" genes or simply a recombining of original genes ?

• Mathematics as a mechanism or tool for inbreeding predictions, while interesting tend to be based on the selection and accuracy of the inputs.  Unfortunately, those formulae that I have seen always seem to leave out critical elements.  The one person and approach that has given me reason to reconsider the value of a mathematical approach is Roy G. Silson and his book: "Additive Genes in Evolution and Selection" .  Mr. Silson applied, and continues to apply a unique approach to genetic inheritance and probability prediction. His thoughts and interpretations of computerized breeding are absolutely fascinating and challenging to find fault with.  He offers a very simple approach to genetic inheritance that questions contemporary analysis and complexity.  It is interesting that similar complex mathematical problems, such as spiders and web construction, were eventually found to be premised on something as simple as the length of the spider's varying legs, silk and web edge.  Could it be that Mr. Silson has identified one of those most sought after and perhaps relatively simple keys to genetic determination and inheritance.  I am not qualified to comment on the mathematical process utilized, simple as they may be, but I can readily see the problems it generates for geneticists and biochemists that have sought complicated pathways to explain increasingly more complex inheritance (polygenic, multigenic etc...)  If this book does not make you reflect and question most of those things that you have heard and learned, I don't know what else will.  On another note, I was pleased to see some of the articles on this site referencing additive genes, and I firmly believe we are beginning to  see more mathematicians and biometricians starting look at inheritance in this same way.

• Inbreeding as the cause of congenital defects.  I think this is absolutely erroneous and not enough can be said to refute this most common of beliefs.  The impact of in breeding and congenital defects has been, much to my surprise, very well handled in articles by those on your site.  However, I don't think they explain congenital defects, brought about by other situations, well enough.  Birds can acquire or be impacted by a number of environmental or climatalogical alterations that can be toxic towards some aspect of egg or embryological development.  The defects are usually obvious in twisted or overgrown beaks, humped backs, loss of toes, peculiar deformities of the foot, polydactyly, muscle contractions or other physical or physiological symptoms.  Unfortunately, the majority of these defects are immediately blamed on, or viewed by those opposed to in breeding, as having been caused by consanguinity.  In captive or caged birds, it is  true that some defects are brought to the surface or exposed by mating close relations.  There are, however, numerous other reasons and causes for problem chicks and structural aberrations, such as in Alaska, where a number of deformities (beak damage) in numerous species of birds have been identified and continue to occur.  Are these species all inbred and that is the reason for the outbreak of beak deformities?  Of course not.  Something else that we are not aware of is happening.  Deformities can be caused by chemical alterations or failures in enzymatic pathways, by rapid changes in temperature in the egg or breeding chamber, problems with the hen's metabolism or mothering and a number of items or conditions other than in breeding, but in breeding is the easy one for people to challenge and undermine.

• Inbreeding results in more sales to the pet market.  In my opinion this is probably the most unrecognized and under-valued reality associated with in breeding. Without in breeding there would be fewer birds and fewer colors available for exhibition or the pet store.  I cannot provide you with a mathematical expectation or probability for mutational events, but my experience has been that mutational events happen because the breeder pairs related birds with recessive genes.  That gene may only be unmasked in a small percentage of birds in a family unit.  The realization of the gene's expression (phenotype), expressivity or penetrance would be highly unlikely, where genes were masked for decades or happened to be recessive to the wild form and the breeder only practiced out crossing.  The presence of a color mutation might suggest to some that a certain amount of in breeding had to have occurred, at some stage, in order to enable the mutation to express itself.  To ensure production of a specific mutation it is implicit in the breeding world that these recessive birds be mated in back cross or sibling cross.  Some will suggest that this is the worst type of matings that you can do,  matings of this type are an old wives tale and that your best chance of mutational success and assessment comes from crossing to the heterozygous wild type bird.  Any other form of mating leads to in breeding and the problems associated with it. Obviously I do not agree with the premise of the reasoning of such statements and would say that your best option is to seek to combine the mutational genes once more.  This, in turn means that all birds of a certain (clearly definable) mutation color will, eventually, all be related.  How closely is irrelevant, but certainly for the color gene transcription component.  The birds may not have been able to reproduce the desired color or achieve the color mutation transfer or fixation without in breeding.  Given this, can we please stop pretending that in breeding is all bad, or that it is a management tool to be abhorred or repudiated.

• Are hybridism and inbreeding essential survival and adaptation mechanisms ?  I believe people will eventually come to the irrefutable conclusion that in breeding and hybridism are survival and adaptation mechanisms, and that breeders currently dedicated to these specific pursuits are merely refining, synthesizing or distilling an infinitesimally small percentage of the variable changes in form or color that our birds are inherently or genetically capable of.  This does not mean that we are breeding or wasting genes, but perhaps developing birds that may be more responsive to changes in environment in the future or generating changes or combinations that certain species may never be called upon to utilize in the wild, given the evolutionary topography, and climatalogical patterns that have slowly evolved over the globe.  In other words, breeders of mutation or hybrids are generating physical evidence of birds that could have, but up to this point have not evolved without human intervention. The greater understanding we develop around and about our birds genetic potential, diversity and combinations, the more accurately we will be able to predict the changes that we can "engineer" through controlled breeding.  This knowledge could be utilized to engineer a bird that could replace a bird species (given that some of the species members were domesticated) following extirpation from a climatalogical catastrophe.  Extirpation being due to the species inability to enhance or increase its evolutionary adaptability and survival. Without species, hybrid and varieties in captivity / domestication, there will be no opportunity at all to replace lost species, unless one wishes to discuss and consider cloning (this leads to a problem in sexual reproduction if the wild bird has not been inbred and undesirable recessives removed.  Inbreeding depression is certainly a reality in this case). This will drive the ecologists and evolutionary biologists wild, as we are talking about replacing a natural species, extirpated by a natural event, by a modified, engineered variety in an ecosystem where other endemic species might evolve to fill the niches.  That the domesticated or captive animals might introduce different bacteria, viruses or other issues into a natural environment is almost a given.  However, the result of such action, whether replacing a natural species with a domesticated form of that same species, or displacing a wild population through captive release is someone else's headache. If the replacement of wild species by domestic animals is not desirable, particularly if the wild species is wiped out by a "natural" plague, virus or weather event, there is really very little left to concern ourselves about regarding in breeding.  However, there remain ethical questions

• Inbreeding can be done by anyone.  Currently, this is absolutely incorrect.  A novice undertaking this activity without a mentor or the knowledge of the standard of the  bird species they have is only seeking trouble and building the potential for more horror stories about the failure of inbreeding.  Inbreeding is a challenging tool that needs to be applied correctly in breeding.  Even the knowledgeable breeder will use these tools with some apprehension and trepidation, because the results can be highly variably.  A good breeder will know his stock intimately and have a solid, practical evidence and knowledge of which birds pass on which traits.  It is this understanding that is applied by the determined breeder, to the act of inbreeding.  If a novice wants to undertake this task, I would highly recommend reading everything that he can get his hands on, particularly earlier books by professional breeders.  He should not contain his reading to birds, but look at all of the mechanisms utilized for improving animal breeding.  Many of these proven methods are applicable across species.

• Agapornis lilianae: Here is an excellent example of confusion around species and potential inbreeding or speciation.  The Nyasa lovebird has always been considered a very "weak" bird outside its natural habitat.  Is the Nyasa in fact so inbred that it can survive no where else.  Is the failure of this species to adapt to changing circumstances, unlike others of its genus, a hint that the Nyasa did in fact specialize and hive off from another group, where-upon its immunity was depressed by inbreeding ,which has led to untold and unexplained deaths ?  Is the Nyasa an example of niche over-specialization in the wild or could it be an example of speciation and inbreeding in the wild ?  Is the swindenaria species the same ?  This bird too, apparently, is also unable to survive outside of its locale and is highly specialized in its seed dietary requirements.  At least we know that hybridization with the Fischer enabled the Nyasa to breed and survive a little better, outside its natural environment than it had before hybridization.  Are these birds so well selected by their natural environment that a loss of genes led to compromised immunity ?