Crossover – Some possible events in my fishroom… ~ Updated 6.27.11 ~

Crossover – Some possible events in my fishroom…

© Alan S. Bias

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

Just what is Crossover?  Or more precisely what is it not?  It is not a mutation, nor does it result in expected phenotype when breeding for specific Y-linked genotype(s).  This event occurs infrequently prior to  the process of fertilization, during meiosis, when genes cross over between chromosomes.  It is most noticeable in events that involve crossover between X & Y chromosomes.  To confuse things even further many times the event is not noticed in the F1, but the F2 offspring.  Ever wonder why pattern is absent, or that less colorful individual appears in a litter of otherwise normal looking siblings and you are reasonably sure he is not a mule (XX male or XXY male)?  In some strains crossover has the potential to go unnoticed by breeders.  Particularly, those in which similar sex linked traits (resulting from single gene or gene complexes) are commonly found on both the X & Y within a strain. 

Crossover in guppies is a concept that has the potential for broad misuse to easily explain events that are otherwise explainable with a better understanding of genetics.  Until recently guppy breeders found little documentation on crossover and knew little to what extent it might influence phenotype.  Yet, we often wondered why an occasional male did not express the same characteristics as his siblings?  We are taught that mutation only happens at rates of less than 1 in > a million.  So, that effectively rules out mutation in these fairly frequent oddities in the fishroom.   

I first took notice of seemingly unexplainable events in my fishroom back in the mid 1980’s shortly after starting to work with Vienna Emerald Green (VEG) Swordtails.  Rather than deciphering it in terms of what happened, I tried to look at things from the standpoint of what did not.  With my fishroom at the time geared more towards showing than genetic exploration, more often than not, such an individual was simply culled as a flaw in the program.  These days I am more inclined to retain oddballs, watch them grow out, and space providing do some test breeding.

Mixed Swordtails in a Community Tank Setting

In Swordtails genotype for color / pattern and sword shape are often found in a related gene complexes.  So it is fairly safe to assume the genes (alleles) reside very close on the same chromosome.  How do I know this?  In part because of the resulting phenotype when suspected crossover occurs.  It was not uncommon, every so often, for a VEG lower male to have nearly perfect pattern and an absolutely clear round tail.  No colored rays and no visible extension.  So how can I consider this as a potential crossover event?  In my Vienna Lower Swords it is possible for females to pass extension and color genetics, but not an X-linked lower swordtail gene(s).  So what is extension?  Just that, the ability to enhance the length of a son’s caudal &dorsal.

Typically, in Vienna Lower Swords both the sword and pattern are Y-linked.  These infrequent clear round tailed individuals have an Emerald Green peduncle and body color, but sometimes lack the “undulating / swirling” pattern needed to be considered a VEG. So at best they might be called of Vienna Type.  They lack the expected Y-linked phenotype for swords, color / pattern, and instead express two X-linked traits.  Those being a clear round tail and color only.  Strangely, I have no recollection of a similar event with Sauer’s type IFGA lower swords.

Vienna Type Male Lacking Sword

Another suspect event that occurred involved Panda Moscow Roundtails.  Every so often a male or two would appear in a litter that lacked expected Y-linked expression of both Moscow pattern and colored roundtail.  Instead these males were nearly devoid of color, less a light iridescent blue cast of spotting, and carried a long narrow caudal.  Much reminiscent of the scarf tails and ribbon tails I bred in the 1970’s as a teenager.  At first I thought this phenotype simply a homozygous expression of the Pink (pk) gene.  If a possible explanation, than pink must be in complex with the new tail shape?  I eventually leaned toward a crossover event after limited test breeding back to “pink” Panda females failed to produce in type any of these males in the F1.

Normal Snakeskin Top Swords

In the last year three distinct events have occurred.  The first involved Snakeskin Top Swords, the second Schimmelpennig Platinum Double Swords in conjunction with Snakeskin Top Sword and the third again Schimm. Platinum Double Swords.  I have been working with these snakeskins for about a year now.  Maintaining in two lines; a pure gold and a mixed grey / gold (blond).  During this time I have run numerous crosses, in both directions, with my other strains of swordtails.  For the most part this well established strain appears Y-linked for both a varied snakeskin gene complex, color, and top swords.

Snakeskin Top Sword * Snakeskin Top Sword siblings with crossover male on right

Too my surprise two males of the last litter lacked both snakeskin pattern and top swords.  As you can see they are clearly wild-type in coloration and finnage.  The caudal is a clear round tail with no visible extension.  As this phenotype is not found in my stocks, and individuals where housed on a stand alone rack consisting solely of related lines, it may be safe to assume these two males are the result of a crossover event.  You will also notice lacking the physiological need to expend resources in growing swords, the dorsals in these males grew out very quickly compared to topsword brothers.

Snakeskin Top Sword * Snakeskin Top Sword siblings with crossover males below

Now the next event is a bit more perplexing.  Over the last decade I have made dozens of pure and cross breedings with Schimmelpennig Platinum Double Swords as the sire.  Frequently with my Vienna Lower Swords in search of a crossover event  involving Y-linked Platinum to X-link.  I routinely breed these Schim. sired females to my Y-linked lower males in hope of creating a Schim. Platinum Lower with fruitless results.  So far the Y-linked  Schim. Platinum gene complex is just too closely linked to a Y- Double Sword gene(s).   (Note:  Keep in mind many double swords result from a Y-link lower and X-link top in combination.  Schim. Platinum are also found in conjunction with lyretail, roundtail, pintail and speartail.  Though, platinum speartail and pintails normally result from Y-link platinum and X-link caudal shape).   

F1 Schim. Platinum Double * Lace Snakeskin Top Sword

Last winter I bred a multi-generation pure Grey Bodied Schim. Platinum Double with gold shoulders * Grey & Gold (Blond) Snakeskin Top Swords.  In part to identify if the latter strain was X-linked for snakeskin &/or top swords, and if so result in a Medusa / Galaxy.  The ½ dozen females I selected contained neither and all males colored similar to the above individuals.  Pretty much identical to their sire, less the addition of a vertical “mood” bar behind the gill plate and on the front shoulder.  This bar gets exceedingly dark during display.  In this case it may result from a snakeskin influence, but may not as the trait appears on occasion in my Schim. * Vienna breedings.  As a precaution I saved one last litter from one of the females.  The female had been left in the same tank in a breeder net with no further exposure to outside males.

F1 Schim. Platinum Double * Lace Snakeskin Top Sword

Her male offspring from this litter are shown above.  At first glance these males look to be Japan Blue.  Those showing green simply reflect the addition of yellow to the pattern.  Did the Top Sword female have an X-link for Japan Blue possibly masked in males by the snakeskin phenotype?  If they remain as is, I suspect these males are expressing the normal metal found as X-linked blue / green base body color found in the strain, less the Y-linked snakeskin overlay.   

Another type of metal?  While the color does extend forward, it is not the typical pattern found in Stoerzbach Metal Swords so I rule it out for the moment.  So, back to the primary issue - Where is the dominant Y-linked Platinum from the sire?  Remember Schim. Platinum males are a combination of platinum and Vienna genetics.  This points us back to a possible crossover event with the resulting phenotype likely an interaction of Emerald Green Iridescent (SmIr) & a X-linked base color.  Space permitting, I may test breed them at a later date. 

F1 Schim. Platinum Double * Lace Snakeskin Top Sword

   While the sheer number is suspect, these young males lend credence to a crossover event.  Multiple traits of the Schim. Platinum & Double Sword gene complex have been suppressed.   The resulting males exhibit non platinum pattern, non Vienna pattern, and clear roundtails or developing lower swords with as of yet no visible extension.  Dams from this cross were on an isolated rack with no known exposure to Japan Blue males.

F1 Schim. Platinum Double * Lace Snakeskin Top Sword

F2 Schimmelpennig Platinum
 sired males

~6.27.11~   Recently I noticed another  possible case of crossover, but have been waiting for the fish to color up.  In a breeding of  F2 Gold Schimmelpennig Platinum Doubles two males were lacking expected pattern.   Not a hint of platinum expression and clear round tails without swords.   Once again multiple traits of the Y-Linked  Platinum & Double Sword gene complex have been suppressed.   The resulting males exhibit non platinum pattern & extension with only partial Vienna pattern.  Within a few days of photographing the dorsals started to color from an X-link for color.

F2 Schimmelpennig Platinum sired males

While I am warming to the concept of crossover it is just not one I wholly embraced.  There are often far to many other genetic explanations for these "seemingly unknown" events.  If this breeding resulted from a multi-generation linebred strain crossoever would be more plausible.  However, the do not.  I frequently utilize my Vienna females in matings with Schimmelpennig males.  Lacking a controlled setting there is margin for error in this example and one should view with skepticism.

Recent publications have shown us crossover can potentially affect, but is not limited to, color – pattern – tail shape.  As a result many breeders quickly rule out the explainable event as crossover.  So are any of these events crossover, or can they too be explained by additional genetic principles?  

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Automated Breeding Systems ~ A cost effective alternative to fishroom's for breeders?

Automated Breeding Systems ~ A cost effective alternative to fishroom's for breeders?

© Alan S. Bias

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

For quite a number of years I’ve thought I would like to automate my fishroom.  The reasons for doing so always seemed about equal to those for not.  With most closed recirculating systems disease issues seem always a concern, even with the most effective and high end UV sterilization in place.  So, until a couple of years ago the only system I really considered with any serious intent is a trough setup using open vinyl gutters to drain tanks and lacking a central filtration unit.  The primary benefits being frequent and convenient water changes.  With this type system water is still fed via a series of pipes and distributed by valves to each tank.  The difference is in while tanks are drilled and fitted with risers & drain tubes in the bottom, sides or both, they are not physically connected to a sealed drain pipe containing co-mingled water from all tanks.  Drain tubes simply sit over a gutter system, and in theory little or no contact exists between tanks.  If the need arises tanks are simply lifted from racks without a need to disconnect plumbing.  This would work well in a dedicated fishroom built from scratch or modified to fit an existing space.

Many are often surprised to see how basic my setup has remained.  By nature I like to piddle around and tinker with things.  So I keep it simple and guppy breeding has remained enjoyable for a number of years.  On the few occasions that circumstances allowed I have designed and built a fishroom to meet my current interests and needs.  More often than not it evolved around an existing room to meet the needs.  For the most part my current fishroom is based on the latter in an existing room using the same setup as my first nearly 30 years ago.  That being racks fashioned from stained 2*4’s.  Not only are they cost effect, but support and distribute a lot of weight without any worries of rust or corrosion.  Allow for full utilization of a small space with some forethought in design.  Additionally they offer a bit of portability when moving or redesigning a setup.  Modification is easy and connecting to other racks for added stability is as simple as adding a piece of 2*4 and connecting with lag bolts.

My personal preference is too secure ends and  any cross braces with three 12-16 penny coated sinkers.  Legs are mitered and notched for maximum stability and load bearing capability.  Each leg is drilled oversize through the rack and connected by a lag bolt with washers and nuts.  Doing so allows for some “play” that is often needed for shrinkage and leveling.  When building, take some time and add extra cross bracing.  Not only will this help prevent warping, but will allow for ease in reconfiguring at a later date if you choose to change tank sizes or locations on your racks.

Wooden racks allow for the most flexibility and ease of modification.  The use of cinder blocks for for legs results in alot of wasted space.  Any after thoughts can be accomplished by drilling, nailing or screwing it in place.  They create nice recessed and hidden locations for wiring, light fixtures, air and water lines.  Personally, I prefer to mount everything on the underside of my racks and above the tanks.  The less clutter on the front of the racks the better.  Neat, tidy and out of the way. 

As they say, “things often change in life.”  Over the last decade I have moved several times with increasing frequency and each time I have wanted to continue raising guppies.  I now realize it just may not be practical to have a dedicated “fishroom” in the future, much less the ability to move all the existing components of the current one.  A setup consisting of large permanent racks; requiring a ton of 48” fluorescent strips based on a rather large number of individual, bulky tanks run off of a noisy blower.   

So I have been pondering designs for a portable stand alone "Self Contained Breeding System" encompassing portions of my current setup & practices.  One sufficient to raise multiple lines of several strains of guppies in a variety of settings.  If desired easily cloned to double capacity.  Initial research pointed to a design similar to those found in a high end laboratory setting with compartmentalized racks.   It did not take much research to realize pre-built systems for laboratories more often than not have limited tank visibility, and are conceived with egg-layers in mind.  For the total volume of water they are just plain expensive.

What I envision is a breeding system more in common with those designed by several Asian breeders in recent years.  Not only would such a system be easy to move, but would need to withstand the rigors of a move on more than one occasion.  Such a setup would need to be both affordable and simplistic enough to be built with my skill set.  Of primary interest is creating a major reduction in the electric foot print now found in most fishrooms.   I’m not sure of the effects on water bound creatures in small confines, but prolonged exposure to Electro Magnetic Fields is negative in nature to human breeders.

  

At a minimum my criteria for a self contained breeding system are:

* High visibility in each compartment, thus eliminating a “plastic shoebox” approach for tanks.

* Ability to locate in a dedicated room or shared space such as a living room or den.

* Need to reduce / contain moisture levels, also aid in heating and lighting efficiency. 

* A hinged collapsible rack design in which lighting and wiring remained in place, while PVC water and airline was easily removed for transport.

* To be both cost effective and transportable with ease individual tanks would be long & multi compartment.  Each tank would use heavy gauge glass to retain heat, and a single piece covering over the compartments.

* Compartment size should take into consideration such factors as overall surface area needed for efficient growth rate per total volume of water in each.

* All tanks should sit on solid wood or similar for additional for insulation.

* Automated for water change.

* A closed recirculating system in which the majority of heating is done in a single location such as the central filter or locations on each level such as the drain pipe.

* Compartments would all have individual filtration, as well as individual cutoffs on all intake and outlets to isolate and quarantine if needed.

* Each level of the rack would have a tank design & compartment sizes geared to a specific goal – breeding trios or groups, large number of fry, grow out of maturing fish, retention of older breeders.
* Covered tanks.  Excess moisture created from uncovered tanks is a common foe in most fishrooms.  The only real solution to the constant humidity is control provided by a dehumidifier in conjunction with a couple small fans to help circulate air.  So covered tanks will not only reduce humidity levels, but aid in retaining heat.

Is such a system possible and practical for the average breeder?  I think very much so.  Still, prior to initial output in time and cost, North American breeders need to abandon both the concept and established practice of purchasing cheap 10 gallon tanks and packing them with fish in large spaces.   While common in Asia and Europe the practice of building tanks from scratch or even modifying existing commercial designs by partitioning is done by few these days in North America.  For myself, such a conversion should be easily accomplished as I rarely crowd my tanks and prefer a very small fishroom for ease of maintenance.  As seen in the photo to the right, over the last 5-6 years I have swapped over a large portion of my fishroom from 10 gallon tanks to ones that measure 48 * 13 * 13 or about 33 gallons in total.  Each is then in turn divided into 4, 6 or 8 individual compartments by further glass partitions.

How many tanks can be held in such a setup?  Quite a few as indicated in Derrick's posting of his breeding systems back in 2006.  His design was one of several that got me started on this idea some years ago.  There is little doubt such a system is can be appealing to the eye:  http://guppyroom.blogspot.com/.   

4 month old Gold (Blond) Bodied Yellow Vienna Emeralds

While dehumidifiers create a welcome source of additional heat in colder seasons, it can be a problem in warm weather.  An often overlooked practice to regulate excess heat in summer and humidity in all seasons is leaving your fishroom door ajar a couple of inches or removing a couple inches off the bottom.  Give it a try...

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Endler's Livebearer ~ a colorful jewel by any classification

Endler's Livebearer ~ a colorful jewel by any classification

© Alan S. Bias

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

Peocilia Wingei or Peocilia Reticulata?   I've been keeping breeding colonies of this Liverbearer for nearly a decade now.  Mostly for simple observation and enjoyment.  While doing an occasional cross with acknowledged strains of  guppies, mostly they just grace my larger planted tanks in breeding colonies.  Harmoniously existing with an admixture of other Livebearers, Tetras, Cori's and Cherry Shrimp.

Surprisingly, I have managed to confine my interests with so much genetic potential and not succumb to tank creep.  For the most part my selection criteria is limited to culling those with clear dorsals and read up on accounts of others via Internet postings.  No reason, just a personal preference.  Something seems to be missing in a clear dorsal.  Admittedly many of the blue/green phenotypes seem to have an association with clear dorsals.  While favoring those with more orange, it is not to the point of eliminating green, blue, yellow or white patches of color.

If you are considering Endler's in a community setting consider a ratio of 2:1 or even 3:1 male to females.  These little guys will hound their mates to near duress more often than not.  I find lower ratios will often lead to many broken down females well before their time from stress induced disease.   Males are so active that they will readily pursue females from most any livebearing species when their own are in absence.  It is not uncommon to see 1/2 a dozen or dozen males relentlessly pursue new females or those that have just dropped a litter.

While some strains appear a bit cannibalistic towards fry, most will not give them a second glance after the first few attain some size.  Without some frequent culling to mimic predation those in a community setting can degenerate into a mob of colorless 1/2 grown individuals.  An approach I often use is to devote several tanks in my guppy room to rearing fry, and then seed my display tanks solely with coloring males.  It is quite impressive to watch 75 - 100 brightly colored males in 55 - 120 gallon tanks, and rivals a well planted tank of Neon and Cardinal Tetra's.

If you are looking for pure stock with a reliable degree of certainty, purchase from a reliable breeder.  When I first started keeping Endler's it still took a bit of effort to find a breeders offering pure stock.  Today it can be as difficult as many of the variations being offered  more often than not appear crosses with guppies vs. pure line-bred strains.  While not always a true indicator, pay attention to any dilution in color or pattern.  Lengthy extension in fin rays or color in females would also be something to question.

So Endlers Livebearer or Cumana' Guppy?  More recent studies hint at what some of us have long wondered.  That being, did scientific classification as a separate species come to early?  With so little differentiation in mtDNA how could this be justified?  The intense coloration of Endler's is not totally unique to them.  Several strains of aquarium guppies also posses similar expression of color.  I routinely breed for it with my grey bodied Vienna Lower Swordtails.  It is rarely seen in conjunction with excessive size. 

 Yet, how would it be possible that such a unique phenotype is not bred out of existence in the wild if truly just a variant?  Current studies suggest that female sexual preference is largely responsible for the existence of Endler's as a recognizable population of guppies within the same range of more traditional populations of guppies.  A few years back such a novel approach might have been scoffed at by aquarists.


Published works on phenotype in isolated populations of guppies as  influenced by female sexual preference have long been  a popular topic in scientific studies.   Now we read similar results on the occurrence of phenotypical variations of Poecilia Picta & Poecilia Parae species.   Not only is shape and size affected by this selection, but also color and pattern.

While I suspect the debate will go on for some years to come, this hypothesis lends much credence to the evolution and existence of Endler's in wild populations of guppies.

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