Part 1: Mosaic gene inheritance

Some basics In the nucleus of each cell, humans

have 23 pairs of chromosomes a total of 46

Offspring will randomly inherit half of each chromosome from their mother, and half from their father

For each observable trait, an organism inherits 2 alleles (2 variations that make up a gene)

Human Father

Understanding Gene Inheritance

50% of genes come from the mother, and 50% come from the father

Dominant: Only one allele is needed to show observable trait (phenotype)Recessive: Two alleles are needed to show observable trait (phenotype)

Heterozygous: Two different alleles inherited

Homozygous: Two of the same alleles inherited

Remember:One half comes from each parent

Chromosome

Momshalf

Dadshalf

2 alleles = 1 gene

b

B

Genotype PhenotypeThe genetic makeup Physical, observable expression of genotype

(color/pattern in our case)

mm

Mm

MM

Non-mosaic

Mosaic

Mosaic

Same phenotype, different genotype!

In theory

DOMINANT GENES

Mosaic (Mm) a dominant gene

Mosaic Father

No

n-m

osa

ic M

oth

er

Mosaic

Mosaic

MosaicNon-mo

Non-mo

Non-mo

If joeys do not inherit the mosaic phenotype, then they do not have the mosaic gene and can not pass it on to future progeny

(Based on empirical evidence)

M = Abnormal gene (Mosaic

m = Normalgene

In theory, inheritance of the mosaic gene should work in a similar way to earlobes in humans.

Those that inherit two copies of the dominant gene EE will have children with unattached earlobes 100% of the time, even if the other parent does not have the dominant gene.

In theory

Mosaic Father Super Mosaic Father

No

n-m

osa

ic M

oth

er

Mo

saic

Mo

the

r

75% of gliders produced by a mosaic x mosaic pairing should be mosaic, with 1 in 3 of those mosaics being a super mosaic (will always produce mos, even when paired with a non-mo)

Mosaic Mosaic

Mosaic

Mosaic Mosaic

Mosaic MosaicNon-mo

Mosaic MosaicNon-mo

Super mosaic

And yet based on breeder observation, it is not possible to breed a super mosaic

Could inheriting two copies of the mosaic gene result in homozygous lethal embryonic death?

Homozygous inheritance of lethal genes exists in horses, cats, rats, alpaca, and mice (1).

1: Gruneberg 1936; Hintz and Van Vleck 1979; Geissler et al. 1981; Niwa et al. 1991; Hosoda et al. 1994; Santschi et al. 1998

Agouti gene in mice

Merle gene in Australian Shepherds

Lethal white in horses

So how can we prove this?

If MM is lethal, then rather than produce a 3:1 (75%) mosaic offspring, mosaic x mosaic pairings hypothetically will result in a 2:1 (66%) ratio of mosaic to non-mosaic offspring.

66%

33%

Why not just use the database?

Oftentimes breeders do not put pet-only gliders in the database. Rarer colors are more likely to be sold for breeding, and thus be put in the database, skewing results.

Part 2: Powdering (graying)

Some famous piebalds before and after

Sparrow

Kaleidoscope

Credit: Tyler Cleckley, Shelley S.

Credit: Priscilla Price

Diamond as a joey

Diamond as an adult

Sometimes, gliders can powder pied (progressive pieds)

Ph

oto

cre

dit

: Ad

ri L

op

ez

Pixie

Ph

oto

cre

dit

: Bri

ttan

y H

.

Possible candidate genes?

Vitiligo gene

Chinchilla/silvering gene

G locus graying gene (what turns gray horses white)

Silvering Gene

Sometimes blood mark patches are left on horses that gray out

Gray at 4 years old

Same horse 3 years later

Part One: Mosaic Gene Inheritance

Must have lineage

Must be breeding mosaic x mosaic

Report how many gliders born mosaic vs. non

Part Two: Powdering (Graying)

Must have lineage

May be pet-only or breeding

Pictures of glider as a joey and as an adult (preferred)

OR your description on whether or not glider has powdered