Some of you might already know that i oppose the breeding practices that dominate our hobby and that i have tried in the past to explain why they are a failure in the long term and furthermore, why they are inmoral.
I thought i should try to be a bit more pro-active about it and make a post laying out a basis for the reasons why this is the case in the hopes that more people will understand the consequences of these actions and why we should try to change this aspect of how our hobby behaves. However, let me point out from the very beginning that this is in no way the whole story, just some of it.
First of all i´d like to present some important phenomena that are necessary to understand the possible ramifications of the current situation.
The first one is the phenomenon known as genetic drift. To put it simply, genes that are not subjected to selective pressures, mutate freely and drift largely at random.
If a gene is subjected to selection, mutations that modify it in such a way that the phenotype it produces in an individual is at a disadvantage, are selected against and elminated from the gene pool whenever they appear. This is what lies behind the principle of survival of the fittest (where fitness is defined as whatever increases survival and reproductive success in a particular context).
In captivity, the vast majority of selective pressures are eliminated or greatly reduced. Animals don´t have to compete with others for food, don´t have to evade predators, may not have to compete for mates and may even not need certain metabolic routes because their diet in captivity is consistent and sufficient to meet their needs of certain vitamins and other compounds.
Since these means that entire sets of genes are therefore not subjected to selection (or the pressures are hugely reduced), these sets of genes are then subject to genetic drift. Mutations acumulate freely because the deleterious effects are trivial in captivity. The survival of the animals is not significantly affected because we adapt to their needs.
This means that captive populations, over generations, may loose entire genetic complexes or gain variations that would not be adaptive in the wild.
The second phenomenon that is highly relevant is genetic association or genetic linkage. Some genes are associated to others, or even entire groups of others. Their inheritance is largely associated because of their possitions in the chromosome. Put simply, genes that are close are more likely to be inherited together.
This means that one phenotype may be inherited in association with other phenotypes. If one or more of those phenotypes is problematic, like a genetic disorder, selecting for a desired phenotype may well imply selection for its associated companions.
The third phenomenon is more specific and it is the active selection for deleterious mutations. Mutations that affect the expression of certain genes can produce new phenotypes which are highly prized by the majority of people in our hobby. Phenotypes of various types such as albinism, hypomelanism, hypermelanism, leucism, etc, are the result of mutations that modify the expression of pre-existing genes. In some cases they modify the degree of expression, their distribution and in others they stop the expression of certain genes.
When we consider pigments such as the various types of melanins, for example, this can be a serious problem because of the negative effects that supressing or diminishing the expression of some of these mollecules can have on the development of neural systems. This is because some of those mollecules are actively implicated in the development and function of the nervous systems. Mutations that affect the expression of this family of compounds can therefore in some cases have effects on the development of the nervous system to varying degrees. This is believed to be the cause of neural disorders in hypomelanistic mutations such as the spider morph in ball pythons or the enigma morph in leopard geckos.
Having pointed out these phenomena, i hope it´s clear that they are significant in the welfare and the future of captive populations.
Our hobby is very clearly dominated by a perspective that focuses almost obsessively on the production of new and rare variations of any kind. The motivations are two fold: commercial interests and the perception that new forms are valuable either because of their aesthetic qualities or their rarity.
This is of course not a new phenomenon among captive populations. Artificial selection has been part of human culture for a very long time, but while originally it was mainly oriented towards practicality, it became all about aesthetics in more recent times. From the victorian era and the obsession with dog breeds to current times and the massive production of morphs of various species, the pursue of form and aesthetics has been the dominant goal in the breeding practices applied to almost every captive population in connection to the hobby of keeping animals.
This has had consequences for these captive populations, in some cases extreme. The species that have been subjected to this particular brand of aesthetics based artificial selection for longer are the ones that have paid the highest price (dogs, pidgeons, poultry, canaries...).
In some instances, the pursue of new variants is quite neutral, since the variants themselves are natural polymorphisms that have no direct or associated effects on the individuals that carry them. In other cases, though, the desired variants are associated to problems or are problematic themselves. Sometimes, as is the case with brachycephaly in many dog breeds, the desired traits are actually severe deformities.
The fact that people are capable of desiring such traits in their animals is profoundly inmoral and extremely worrying, even more so because often times people are completely blind to the facts of what these traits imply. The willingness to ignore or downplay the effects of such traits is what drives the continued quest for the next one and the perpetuation of the already existing ones.
So as a consequence to all this, the reality is that currently, the vast majority of breedings of many, many species, are either randomized, meaning that there is no explicit selection whatsoever (and therefor that fitness is not a factor), or that the only selective criteria applied are oriented towards the production of variants of some kind or another.
In the light of the previously explained phenomena and the effects of both lack of selective pressures geared towards general fitness and the application of selection based solely on aesthetics and rarity, i hope it´s clear that the current system has only one possible outcome if it continues to exist as it is: the empoverishment of genetic fitness of all subjected captive populations and the purposeful acumulation of deleterious traits.
As i said in the beginning, this is nowhere near a complete description of the failures of current breeding practices, but i hope it will serve to inform and to raise consciousness about the importance of changing the obvious flaws in how things are being done for the sake of our animals and their future generations.
I thought i should try to be a bit more pro-active about it and make a post laying out a basis for the reasons why this is the case in the hopes that more people will understand the consequences of these actions and why we should try to change this aspect of how our hobby behaves. However, let me point out from the very beginning that this is in no way the whole story, just some of it.
First of all i´d like to present some important phenomena that are necessary to understand the possible ramifications of the current situation.
The first one is the phenomenon known as genetic drift. To put it simply, genes that are not subjected to selective pressures, mutate freely and drift largely at random.
If a gene is subjected to selection, mutations that modify it in such a way that the phenotype it produces in an individual is at a disadvantage, are selected against and elminated from the gene pool whenever they appear. This is what lies behind the principle of survival of the fittest (where fitness is defined as whatever increases survival and reproductive success in a particular context).
In captivity, the vast majority of selective pressures are eliminated or greatly reduced. Animals don´t have to compete with others for food, don´t have to evade predators, may not have to compete for mates and may even not need certain metabolic routes because their diet in captivity is consistent and sufficient to meet their needs of certain vitamins and other compounds.
Since these means that entire sets of genes are therefore not subjected to selection (or the pressures are hugely reduced), these sets of genes are then subject to genetic drift. Mutations acumulate freely because the deleterious effects are trivial in captivity. The survival of the animals is not significantly affected because we adapt to their needs.
This means that captive populations, over generations, may loose entire genetic complexes or gain variations that would not be adaptive in the wild.
The second phenomenon that is highly relevant is genetic association or genetic linkage. Some genes are associated to others, or even entire groups of others. Their inheritance is largely associated because of their possitions in the chromosome. Put simply, genes that are close are more likely to be inherited together.
This means that one phenotype may be inherited in association with other phenotypes. If one or more of those phenotypes is problematic, like a genetic disorder, selecting for a desired phenotype may well imply selection for its associated companions.
The third phenomenon is more specific and it is the active selection for deleterious mutations. Mutations that affect the expression of certain genes can produce new phenotypes which are highly prized by the majority of people in our hobby. Phenotypes of various types such as albinism, hypomelanism, hypermelanism, leucism, etc, are the result of mutations that modify the expression of pre-existing genes. In some cases they modify the degree of expression, their distribution and in others they stop the expression of certain genes.
When we consider pigments such as the various types of melanins, for example, this can be a serious problem because of the negative effects that supressing or diminishing the expression of some of these mollecules can have on the development of neural systems. This is because some of those mollecules are actively implicated in the development and function of the nervous systems. Mutations that affect the expression of this family of compounds can therefore in some cases have effects on the development of the nervous system to varying degrees. This is believed to be the cause of neural disorders in hypomelanistic mutations such as the spider morph in ball pythons or the enigma morph in leopard geckos.
Having pointed out these phenomena, i hope it´s clear that they are significant in the welfare and the future of captive populations.
Our hobby is very clearly dominated by a perspective that focuses almost obsessively on the production of new and rare variations of any kind. The motivations are two fold: commercial interests and the perception that new forms are valuable either because of their aesthetic qualities or their rarity.
This is of course not a new phenomenon among captive populations. Artificial selection has been part of human culture for a very long time, but while originally it was mainly oriented towards practicality, it became all about aesthetics in more recent times. From the victorian era and the obsession with dog breeds to current times and the massive production of morphs of various species, the pursue of form and aesthetics has been the dominant goal in the breeding practices applied to almost every captive population in connection to the hobby of keeping animals.
This has had consequences for these captive populations, in some cases extreme. The species that have been subjected to this particular brand of aesthetics based artificial selection for longer are the ones that have paid the highest price (dogs, pidgeons, poultry, canaries...).
In some instances, the pursue of new variants is quite neutral, since the variants themselves are natural polymorphisms that have no direct or associated effects on the individuals that carry them. In other cases, though, the desired variants are associated to problems or are problematic themselves. Sometimes, as is the case with brachycephaly in many dog breeds, the desired traits are actually severe deformities.
The fact that people are capable of desiring such traits in their animals is profoundly inmoral and extremely worrying, even more so because often times people are completely blind to the facts of what these traits imply. The willingness to ignore or downplay the effects of such traits is what drives the continued quest for the next one and the perpetuation of the already existing ones.
So as a consequence to all this, the reality is that currently, the vast majority of breedings of many, many species, are either randomized, meaning that there is no explicit selection whatsoever (and therefor that fitness is not a factor), or that the only selective criteria applied are oriented towards the production of variants of some kind or another.
In the light of the previously explained phenomena and the effects of both lack of selective pressures geared towards general fitness and the application of selection based solely on aesthetics and rarity, i hope it´s clear that the current system has only one possible outcome if it continues to exist as it is: the empoverishment of genetic fitness of all subjected captive populations and the purposeful acumulation of deleterious traits.
As i said in the beginning, this is nowhere near a complete description of the failures of current breeding practices, but i hope it will serve to inform and to raise consciousness about the importance of changing the obvious flaws in how things are being done for the sake of our animals and their future generations.
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