Cross 8
Purpose: Fourth backcross to restore the Snow White phenotype
Male (Gandalf):
Bought from a big box store during February 2023 as part of the initial stock.
Strain: Snow White
Relevant genes. Some are assumptions, indicated with italics. Although their decedents strongly support the claims:
Base body color: Blond (bb)
Magenta: likely homozygous (MM)
European Blau: (rr)
Stoerzbach: (ss)
Female (C2AF):
Gandalf’s daughter from Cross 2.
Strain: Half Snow-White
Relevant genes. Some are assumptions, indicated with italics. Although their decedents strongly support the claims:
Base body color: Gray (Bb)
Magenta: likely a carrier (Mm)
European Blau: (Rr)
Stoerzbach: (Ss)
Offspring:
Born: March 21, 2024
Brood Size: 41
15 Male
26 Female
Offspring phenotypes and genotypes:
The figure above shows all the male phenotypes ordered by the relevant genes that showed an obvious phenotype. Base body color, European Blau, and stoerzbach: I will use the grid as my grouping labels.
The females followed a similar phenotype distribution except for stoerzbach. I had a hard time telling apart females that expressed stoerzbach.
Genotype distributions. Numbers indicate the distribution with-in just the males.
A1: Bb|(MM or Mm)|Rr|Ss, 4 males, 26.7%
B1: Bb|(MM or Mm)|Rr|ss, 3 males, 20%
C1: Bb|(MM or Mm)|rr|Ss, 1 male, 6.7%
D1: Bb|(MM or Mm)|rr|ss, 1 male, 6.7%
A2: bb|(MM or Mm)|Rr|Ss, 3 males, 20%
B2: bb|(MM or Mm)|Rr|ss, 1 male, 6.7%
C2: bb|(MM or Mm)|rr|Ss, 2 males, 13.3%
D2: bb|(MM or Mm)|rr|ss, 0 males, 0%
My expectation was that each of the 8 unique phenotypic combinations (resulting from three genes) would represent roughly 12.5% (indicated by the dotted line) of the offspring. This is because the C2A female is heterozygous for each gene, while Gandalf is homozygous (similar to Cross 7). This means each individual gene should show an even 50% distribution of its two phenotypes. At first glance, the overall phenotypic distribution seems uneven, particularly A1. However, after examining the distributions of each gene individually, the picture becomes much clearer:
Base Body Bolor: 18 Blond : 23 Gray (Both males and females).
European Blau (EB): 17 EB : 24 Non-EB (Both males and females).
Stoerzbach: 5 Stoerzbach : 10 Non-Stoerzbach (These values reflect males only).
For genes where C2AF is heterozygous and Gandalf is homozygous, we expected a near 50% split between the two phenotypes. Although we are slightly below this distribution we are still near enough for the relative brood size.
Notes:
I intentionally didn't focus heavily on magenta gene expression in this cross. The variety of phenotypes already present was extensive, and adding magenta to the analysis would have introduced significant complexity. However, given that magenta is incompletely dominant and Gandalf is likely homozygous (MM) for the gene, all offspring would inherit at least one magenta allele. C2AF, being Gandalf's daughter, is likely heterozygous (Mm) since her mother from Cross 2 (Female #2) probably lacked the magenta gene. Therefore, all offspring in this brood are either MM or Mm. Based on color alone, these phenotypes should be largely indistinguishable. Fin size, however, is a different matter. Magenta is thought to reduce fin size. I believe this largely occurs in its homozygous state, which aligns with its incomplete dominance. While I didn't collect specific fin size data for this brood, I do recall observing both long-finned and short-finned males. See male in slot A2 in the chart above or photo below for instance. Or the mother (C2AF) herself. However, without precise data, a proper distribution analysis isn't possible at this time.
There was an interesting male that showed up that had elevated iridescence on his forehead. I am not sure where this came from but if I had to guess, it had to do with female #2 from Cross 2. She looked similar to some dragon strains which do sometimes have elevated levels of iridescence. I plan on using him to pass this trait along to the snow white line. The goal is to hopefully cover the head of the snow white guppy with a fully iridescent forehead. I labeled him as Cross 8 Male A (C8AM) whom I later named Thorn.
I used C8AM (Thorn) for Cross 14. He was paired with one of the more unique females out of this brood. The female he was paired with was labeled as Cross 8 Female B (C8BF).
C8AM (Thorn) was used again, paired to a snow white female from Cross 11 (C11AF). This established Cross 15.
C8AM (Thorn) was used once again, paired to one of his daughters from Cross 14 (C14AF) to try and establish Cross 17.
I selected 2 females with a phenotype closest to snow white as breeders for a subsequent cross. These females were paired with C7AM from Cross 7, establishing Cross 13. These females were labeled Cross 8 Females A (C8AF).
A YouTube video detailing the start of Cross 8 can be found here.
C8AF
C8BF
Male with larger tail