LONGEVITY AND FERTILITY OF LOWERSWORD MALES

Both longevity and fertility can be linked to genetic and environmental inputs.  Can negative result be alleviated with positive selection practices?

First of two surviving 40+ month old Blond Bunt Ls breeder males.

 

Second of two surviving 40+ month old Blond Bunt Ls breeder males.

© Alan S. Bias

Permission granted for nonprofit reproduction or duplication of photos and text with proper credit for learning purposes only.  August 13, 2024 

Several years ago I decided to test the current longevity and fertility of males in my Lowersword strain.  Something I had not done for some time.  I kept a group of 4 sibling Blond Bunt Ls males until demise in an active breeding group. Periodically replacing all females with new virgin females to keep aged males active. All males lived well over 40 months and were fertile until demise. The last two met thier fate this past Spring within days of each other.

Last surviving 40+ month old Blond Bunt Ls breeder male.

I should state from the outset, that I am a pedigree breeder of livestock. Not a breeder of Show Guppy phenotypical classes.  My breeding practices follow those conventional to any domestic breed across species with small refinements applicable to rearing Guppies.  In this case my breed of choice is a domestic Poecilia reticulata Lowersword strain.  What is the primary difference you may ask?  A pedigree strain if succesful, like those produced on any farm across domestic breeds, will persist in recognizable form for many years well past my time as a breeder.

A common theme often passed to me as a young breeder by old-timers basically said, "the sign of success for any breeding program is not how many ribbons are aquired in the show ring.  Rather how many herds and flocks your breeding program has founded or influenced along the way within your breed of choice"  To this end, I set out to several decades ago to recreate the modern image of  a Swordtail Guppy within the International Fancy Guppy Association (IFGA).  In the form of a linebred maternal pedigree breeding strain.  During the process I seemed to have expanded my initial goals.

To date my Lowersword strain has been directly sent or taken by myself or other breeders to over 40 US States including Hawaii & Alaska, Brazil, China, Japan, Taiwan, Thailand, Indonesia, Malaysia, Singapore, Vietnam, Australia, South Africa, Germany, Austria, France, Italy, Poland, Romania, Bulgaria, Norway, England, and Canada. Several other European & Asian countries slip my mind at the moment.

William Storrie, a noted and wise old Belted Galloway cattle breeder and acquaintance once stated, excerpt [Conservation of genetic endowment in a small (40 females/4 lines) nucleus cannot conserve the genetic variation of the breed. It is simply a snapshot at one particular moment of time from one specific viewpoint... …a reference point…].  As a pedigree breeder, I seek to show and promote only those individuals which are representative as a genomic snapshot of the actual breeding stock in my program. A reference point of those individuals utilized to reproduce the strain in a continuing fashion.

I maintain a linebred, and generally closed maternal pedigree breeding program over many generations. From which I simply show those individuals best suited for the show bench. Little different from any domestic pedigree breeding program across species. All breeding’s consist of several female X-link lineages and a single Y-link male lineage.  Yes, each and every male and even females in my breeding program descend from a single prepotant foundation sire.  One with the genotype needed to found a strong paternal lineage in a recognizable lowersword form.  Less than a dozen outside females have been brought in, to infuse novel color-pattern genes not already present, since inception of the current combined Lowersword strain ca. 2002.  In most cases, new female X-link genes were eliminated after infusion of desired autosomal gene(s) for color-pattern had been accomplished.

Contrary to many “Show Guppy” or "Commerical" breeders who set size and early maturity as the primary criteria, I do not make planned terminal outcross breeding's, from within established lines or via infusion of unrelated stocks, solely for the purpose of producing non-breeding, fast growing and large bodied F1 hybrid offspring destined for show or sale. Such individuals are genetic "dead-ends" that do not contribute to future generations, and are of no value in my fishroom or breeding program.

Nor, would they be representative of my pedigree breeding program.  A sound breeding program is one in which positive beneficial genes are identified through autosomal accrual.  While attempt is made to identify and eliminate negative genes before autosomal accrual can occur.  Selection of genes for both longevity and fertility are part of this process in a pedigree breeding program.

Three month old Asian Blau Blond Bunt Ls male.

Longevity and fertility in my Lowersword strain are not solely the result of physical attributes, i.e. "moderate body size & a lighter caudal weight". Just as lack of longevity and fertility in Broadtails are not solely the result of physical attributes, i.e. "large body size & a heavier caudal weight".

Nor is longevity and fertility in my Lowersword strain solely the result of reduced environmental inputs with age, i.e. reduction of dietary inputs, water temperature reduction, or water changes. All fish, regardless of age, receive the same daily feedings of live (Baby Brine Shrimp – BBS) and prepared flake food mixes. Each and every tank receives the same feeding regimen based solely on the total volume of fish it contains.  All ages groups and sexes are maintained in haphazard fashion in all rows, racks and tiers without regard to temperatures.  All tanks recieve the same percentage of water change each week.  Breeders and show fish tend to be housed on higher tiers, with higher corresponding temperatures, for ease of viewing.

Yes, this may seem counter-productive to accepted practice for longevity and fertility of current individuals in optimum age-based form used to breed or for show.  As the majority of my show fish, both males and females, are actively engaged in breeding groups.  However, I wish to identify those individuals that fail to thrive under moderately high inputs and eliminate them from the gene pool.  I seek to identify those who thrive in mixed age breeding groups well into advanced age.  Remove those that are obviously infertile, become "chesty" or otherwise "obese" and cannot metabolize the same ration as efficiently as other male and female cohorts of various ages in the same settings. 

Longevity and fertility are in part based on positive selection for specific aspects of fecundity over multiple generations.  In the case of my Lowersword strain 80-100+ filial generations since prior noted inception date of 2002. Generations are not always sequential, i.e. each breeding is not intended to increase the filial count. Many breeding’s involve either paternal (BC1) or maternal (BC2) backcrosses. All of which are common practices in domestic pedigree livestock breeding.

Grey Vienna Emerald male expessing Type2 Bunt (Bu2)
erythrophore based coloration over iridophores.

Often, a percentage of breeding’s are linear using the same generation in multiple breeding’s over a period of 2-3 years. It has long been my feeling that if current breeding results are positive, then there is no need to progress to the next filial generation. As you risk the chance of a decrease in one or more aspects of fecundity within a small gene pool. My Lowersword are maintained by numerous breeding’s each year in no less than 40 tanks and currently 70 tanks. It has run as high as 80-100 tanks in the last few years. This is still a small number when 650 breeding age females is considered the bare minimum to maintain a small population.

Many productive and/or prolific breeding groups are kept intact. Fry are saved over multiple parturitions, i.e. “long-cycle breeding” is practiced. Resulting in a larger potential breeding population with mixed attributes. As opposed to “short-cycle breeding” practice geared toward maximum number of same age males & females for a show season. Which is often based on saving fry only from the first 1-2-3 parturitions. Then culling all brood females and no longer utilizing sires for additional breedings. 

Why is long-cycle breeding practice important?  It forms the basis for linking both longevity and fertility together within your males and females.  Short-cycle breeding schemes can impose negative selection on both longevity and fertility in very few generations. Over time, producing a smaller breeding population with a narrow set of homogeneous attributes.  One which relys on frequent outcross of stocks shared among breeders in compatible breeding schemes to mask weaknesses.

This is not to say a breeder should not make use of limited short-cycle test breeding’s and save a litter or two for evaluation. Retaining results if superior and culling when inferior. To once again reference William Storrie, excerpt [The top two [bull calves, sic each year] are mated to four of the worst heifers (two each) and the rest are fattened and killed…]. A practice which I mimic with many of the best top end males I rear out that were not initially selected to be included in long-term breeding groups.  If you take the time to raise them out, test breed them in the interim.  Retain and infuse positive results into your breeding program.

3 month old Grey Bunt Ls males expressing
both Type1 & 2 Bunt (Bu1 & Bu2) coloration.

3 month old Grey Bunt Ls male expressing
both Type1 & 2 Bunt (Bu1 & Bu2) coloration.

       3 month old Grey Bunt Ls males expressing both Type1 & 2 Bunt (Bu1 & Bu2) coloration.

While the results of my simple test for longevity & fertility are somewhat anacdotal in nature, it does provide insight into current extreme age range for both traits in my linebred breeding population.  These two aspects of fecundity have not been reduced or lost over the years.  Either within my breeding population or as historically reported in P. reticulata (Comfort, Alex 1961).  While not all males, or females, will achieve this result, I am pleased to know a percentage still do.  That is the intent.  As based on practices which I have long adhered to in pedigree cattle, sheep and fish breedings over the last 4 decades.  I am even more pleased to know that these two traits appear to have been succesfully linked together, and that I'm not simply retaining sterile males and females into old age.  Can you say the same for your breeding population?

References:

Storrie, Wm., 1993 Some Observations on Belted Galloways, Correspondence from William Storrie, Netherwood Farm, Bathgate, West Lothian

https://beltie.org/articles/some-observations-on-belted-galloways.php  Last checked 8.13.2024.

Comfort, Alex. "The longevity and mortality of a fish (Lebistes reticulatus Peters) in captivity." Gerontology 5.4 (1961): 209-222.

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Final thoughts I will leave to the late Bill Storrie, excerpt [Most deleterious genes involving fitness are recessive… …breeders nearly always opt to mask their effect by outcrossing. But inbreeding doesn’t MAKE bad genes. It is the process that FINDS bad genes that already exist in the genetic endowment (the genome of the breed or species).  And allows breeders to eliminate them, or reduce their frequency.  If bad genes exist at a high frequency they will be found quickly: at a low frequency only after many attempts to uncover them.  If none EXIST none will be FOUND.] 

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