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Tuesday, May 10, 2011

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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