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Wednesday, January 11, 2012

Science as A Tool and Benefit to Guppy Breeders…


Science as A Tool and Benefit to Guppy Breeders…

© Alan S. Bias
Permission granted for non profit reproduction or duplication of photos and text with proper credit for learning purposes only.

January 11,  2012

Grey Vienna Emerald Lower with Blue Peduncle
Outcrossing is often offered as a cure all for a declining strain showing the effects of inbreeding. However, this is not the whole story. Just as the negative aspect of inbreeding can be described as inbreeding depression, outcrossing can result in outcrossing depression. What is “out-breeding depression?”  The answer can be found in one of the many tools available to the successful guppy breeder.  Science… Out-breeding depression is a loss of robustness due to reproduction among very dissimilar individuals; characterized as hybrid breakdown.

Out-breeding to a substantially different strain can break up the gene complexes needed to produce the initial traits a breeder is selecting for.  Science is not the cure all for a guppy breeder.   It is but one of many tools that can be used to balance out a successful breeding program for show, research, preservation or plain eye appeal.

Grey Asian Blau Lower with Z-Bar and Blue Peduncle
Understanding of traits we now take for granted such as blond (gold), albino, snakeskin, basic caudal extension all resulted from breeding experiments, analysis and testing of hypothesis.  Breeding guppies is already a science for those who take it seriously and are willing to admit it.

As a breeder I view guppies as a genetic puzzle to be decoded and expanded upon through phenotype.  Over the last 100 years our knowledge as grown by leaps and bounds.  Try to imagine the entire potential of the guppy genome.  You cannot.  Each of us is bound by our narrow focus on not only how we describe a quality guppy, but the breeding technique(s) we use to obtain them.  If a breeder is not careful self imposed limitations may hinder our interpretation of accrued knowledge from all sources and its possible uses.  To further compound events as breeders we often do not document results of our crosses very well. 

Breeders should consider the possibilities as they present themselves.  In example; a cull is not just an individual who fails in expectations.  You can still learn from it.  Did it come about from crossover or simple recombination of alleles?  Worse yet, will a gene complex inhibit your desired goals or is a form of gene regulation preventing it?

2.5 month old Asian Blau Blond & Grey Vienna Lower 
There are many elements that compose the whole of breeding domesticated guppies.  They include:  purebred, hybrid, research, enhancement, sale, and show to name a few.  Value of each is determined by personal interests.  Therefore, no single component or the resulting fish is of greater value than another in genotype if healthy and viable.  Breeder preference should not be misconstrued to suggest otherwise.  In each case the primary criteria for selection of potential stock should be limited to:  “Has it been bred toward goals that reflect my intended use and will it reproduce to type?”

Preservation, Improvement, and Promotion are considered the primary functions of a breed association. Showing is normally considered a by-product of purebred stock breeding, and is prohibited by some tasked w/preservation of gene pools to avoid judgment that results in inflated value.

Show stock is an expression of a particular phenotype and not always a reflection of breeding value.  Only a very small percentage of any purebred (registered) population is considered to be of show quality.  It takes the use of diverse breeding techniques by individual breeders to promote overall population health.  The value of purebred strains is to produce predictable results within itself and for infusion into that part of a population which does not.

Many authors continue to profess the benefits of out-breeding as a cure all for a declining strain showing the effects of inbreeding.  Normally I refrain from directly critiquing others, even when positive in intent.  Last month on one of my regular web rambles involving “Guppies” as part of the search criteria I ran across an article posted to the Malaysia Guppy Forum.  Originally published in the IFGA eBulletin Volume 7 # 7 July 2011, and titled “Follow the Best Genetics by Jim Alderson.”  It was originally a short article written by a prominent IFGA officer and breeder that has had me pondering ever sense.  Though vague in use of terms, it was not so much the content of the article that created issue for me as the perceived intent of summation.

As a linebreeder, in general, I could agree with much the author stated if his implication was his successful hybrid crosses are limited to highly inbred IFGA strains.  Broad based statements lacking clarity of definition are subject to a wide range of interpretation.  Crosses involving non IFGA strains or even dissimilar IFGA strains have the potential to be subject to out-breeding depression.  As a result, there are several conclusions offered by Alderson where I would disagree based not only on personal experiences as a breeder, but backed by scientific knowledge.

An example is: “Selecting more dissimilar fish will give you a wider range of variability and more hybrid vigor.”  Unless the intent was to introduce traits not already found in my strain, in this instance one could state that, “such an approach is just as likely to result in out-breeding depression in a fixed strain.”

In another quote, A more sustainable approach is to use out-crossing to instill new genes into your pure lines and make rapid improvement in your stock. Remember, every time you out-cross you are improving the hardiness and disease resistance of the the fish as well.”  One could easily state that, “such an approach is just as likely to result in out-breeding depression in a fixed strain by reducing or eliminating positive benefit derived from already existing co-adaptive gene complexes for disease resistance.”

Grey Schimmelpennig Platinum Lyretail
While we lack corresponding “registration papers,” as found in animal breed associations, with line-bred Guppy strains an old adage in the Pedigree Livestock World is very applicable.  It simply states, “A pedigree is only as good as the breeder who produced it.”   This is a personal preference based on not being interested in creating hybrids for show.  As a result I seek out methods that will reliably produce sound pedigreed breeding stock and promote the results.  I would not take a route that derives short-term result from long-term failure.  Genetic dead-ends are of little value in a breeding program.

Some years back I wrote a couple articles for the sheep world that were published by several breed groups:   Breeding Strategies and Genetic Manipulation ~and~ Breeding Strategies and Genetic Consequences.  Recently, after review, retired biology professor Richard “Rick” D. Squire, Ph. D., and now active guppy breeder felt I should rework them for the benefit of other breeders.  Here are the links to each as rewritten:    
                                                                                                                                      
~ and~

There has always been a view in show circles that claims many new breeders are successful until they step out of the box, break from established practice and try to do things on their own.  This seems to indicate much initial success results from starting off with reliable strains produced by those breeders who utilize all tools available.  Tools which can provide definition to the more static results we often observe as breeders to provide forethought in planning matings.  Science is one of them. 

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In the end what was in Alderson’s summation that was so perplexing it led me to spend several weeks procrastinating a response?  It stated:  Guppy genetics is not a science. Guppies are a tapestry that we can learn to paint with a few genetic principles, trial and error, and records. Those who claim to study guppy genetics do so by making the crosses and dissecting the results, not by predicting the outcome in advance, claiming to have discovered the inheritance of a new trait, until the next cross is made that does not follow the rules. Breeding guppies may someday be a science, but I will be pushing up daisies by then.

Having thought about this statement for some time, it dawned on me what I found so disconcerting is that a prominent IFGA officer and breeder would not only appear to frown upon, but downplay one of the organizations founding principles as stated: 

IFGA Constitution
ARTICLE 2 – PURPOSE AND OBJECTIVES

Section 2.1 – Purpose
            2.1.1    To promote interest in, and scientific knowledge about guppies.

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1 comment:

  1. Hey hey,
    I think all genetics is science.
    Simply, what other class might you study/teach genetics in but Science ?

    Guppy breeding is/can be a science experiment.
    It is what you make it to be.
    Jim states "not by predicting the outcome in advance".
    Every breeder/hobbyist has a thought, intention, hope or expectation of desired results from each cross or breeding.
    Thus predicting the outcome in advance yes.
    Ones intent could be to eliminate "out-breeding depression" :)
    But then "out-breeding depression" could be the result of many other factors (environment, nutrition, temperature etc...) and perhaps concluded as "out-breeding depression".

    Have a blast !
    John

    ReplyDelete