It seems I have .... still time.
The original 34 were captured in Xochimilco and contained one leucistic indivdual in 1963. These werd shipped to the FMNH and Auguste Dumeril established a successful breeding colony here from 5 male and 1 female axolotl only. The leucistic specimen received much attention from scientific experts as the phenotype is associated with the morphogenetic behavior of neural crest-derived pigment cells and is quite different from the dark mottled green and black of the wild phenotype.
The population bred by Dumeril quickly reached thousands of specimens and these were distributed widely across Europe among researchers and aquarists quickly. Over time they became a model species for studies in developmental biology, evolution, reproduction and regeneration. Then in 1932 from a lab in Poland stock was send back to Ross Harrison's lab at Yale from where a small group was gifted to Humpreys to the University of Buffalo to Humpreys lab. Here, scientists brought in a series of wild axolotls to mix up the gene pool and at one point even added in tiger salamanders (Ambystoma tigrinum). The Buffalo population thrived and eventually moved to the University of Kentucky in Lexington, which is now the centre of global axolotl breeding. This means that, in addition to being inbred, almost all of the axolotls in labs and aquariums today are actually part tiger salamander.
The unique phenomenon with axolotl is explained in some detail here:
I QUOTE
The white phenotype results from a recessive allele,
d, at a single locus11 and white mutants figured prominently in demonstrating that vertebrate pigment cells are derived from neural crest cells12. Studies over several decades established that white mutants have defects in the morphogenesis of black melanophores and yellow xanthophores11,13,14,15,16,17. In wild-type (
D/-) embryos, melanophores and xanthophores begin to differentiate in the premigratory neural crest along the dorsal neural tube and migrate from this position to cover the flank. In white (
d/
d) mutants, fewer melanophores and xanthophores differentiate, and most fail to migrate. Subsequently, melanophores and xanthophores that did differentiate are lost, presumably by cell death, and late-appearing, iridescent iridophores fail to develop. Thus, white larvae and adults are typically devoid of all pigment cells, although occasional adults have been reported to develop patches of melanophores18, likely arising from post-embryonic stem cells19. Additional analyses have indicated that the white gene acts non-autonomously to pigment cells in promoting their development; for example, wild-type epidermis or subepidermal extracellular matrix can rescue pigment cell migration in white mutants12,14,17,20. Despite its striking phenotype, natural origin and historical significance, the genetic basis of the white phenotype has been a mystery21.
Another historic axolotl pigment phenotype is albino (
a), in which melanophores develop but remain unmelanized22. Surprisingly, the albino phenotype did not arise within the axolotl lineage but was instead established by interspecific hybridization23. In 1962, a terrestrial tiger salamander (
A.
tigrinum) lacking melanin was collected near Foot Lake, Willmar Minnesota and after almost a year in captivity, it was gifted to Rufus Humphrey at Indiana University. Humphrey knew it was possible to cross a terrestrial, metamorphic tiger salamander to an aquatic paedomorphic axolotl by
in vitro fertilization24. Unfortunately, embryos from the interspecific cross he performed began to die. As a work around, Humphrey and colleagues used cutting edge technologies for the time – somatic cell nuclear transfer and microsurgery – to create embryos that carried the albino gene. Descendants of these species hybrids were crossed into various axolotl strains and are maintained today in the Ambystoma Genetic Stock Center (AGSC; University of Kentucky)."
UNQOUTE
Identification of Mutant Genes and Introgressed Tiger Salamander DNA in the Laboratory Axolotl, Ambystoma mexicanum
Basically what we are looking at now is that most if not all albino axolotls are in effect hybrids. This dates back to back-crossing in 1964 with the F2 offspring of a F hybrid albino
Ambystoma tigrinum and a male white phenotype/leucistic
Ambystoma mexicanum. If you have an albino axolotl, you can trace its ancestry back to this lab experiment.
NOTA BENE: Even before the deliberatie introgression with Tiger salamander A. tigrinum it was already suspected that hybridisation had occured in animal markets with A. velasci.
Literature:
Identification of Mutant Genes and Introgressed Tiger Salamander DNA in the Laboratory Axolotl, Ambystoma mexicanum | Scientific Reports
Tale of Two Axolotls
https://media.nature.com/original/magazine-assets/d41586-017-05921-w/d41586-017-05921-w.pdf
What Do We Lose If We Lose Wild Axolotls?
Salamander Models in Cross-Disciplinary Research - Meeting Report - the Node