Budgerigar Genetics
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http://en.wikipedia.org/wiki/
Budgerigar_colour_genetics
The science of budgerigar colour genetics deals with the heredity of mutations which cause colour variation in the feathers of the species known scientifically as Melopsittacus undulatus. Birds of this species are commonly known by the terms 'budgerigar', 'budgerigar parakeet' or just 'budgie'.
Recessive Pied
Background
The Wildtype (natural-coloured or wild occurring) Budgerigar Parakeet's colour is called Lightgreen. The feathers of most Parrot species, including Budgerigars, contain both a black type of melanin named eumelanin along with a basic yellow pigment named psittacofulvin (psittacin for short). Some other Parrot species produces a third pigment named advanced-psittacin which enables colours & tones ranging from oranges, peaches, pinks to reds. When these feathers are exposed to a white light source, such as sunlight, only the blue part of the spectrum is reflected by the eumelanin granules. This reflected blue light passes through the yellow pigment layer, resulting in the green colouration known as Lightgreen in only the Budgerigar Parakeet &/or Green in any other naturally green coloured Parrot species.
The many colour variations of Budgerigars, such as Albino, Blue, Cinnamon, Clearwinged, the various Fallows, Grey, Greygreen, Greywing, Lutino, Mauve, Olive, Opaline, Spangled, Suffused, Violet... are the result of mutations that have occurred within specific genes. There are actually at least thirty-two known primary mutations established among Budgerigar Parakeets. These can combine to form hundreds of secondary mutations & colour varieties which may or may not be stable.
As is true with all animal species, colour mutations occur in captivity as do in the wild. This has been demonstrated when captive-bred Budgerigars have developed mutations that had only been previously recorded amongst wild populations.
Classification of mutations
Basic groups
Each of the thirty-two primary mutations belong to one of the four basic groups of mutations classified in parrot species genetics:
Albinism : where eumelanin is either partially or completely reduced in all body tissues & structures.
Dilution : where eumelanin is partially reduced in only feathering.
Leucism : where eumelanin is completely reduced from total or localized feathering.
Melanism : where eumelanin is increased in the feathering.
Dominance relationship
These mutations are inherited through one of the following dominance relationships.
▪ autosomal-Co-Dominant (A-Co-D),
▪ autosomal-Complete-Dominant (A-C-D),
▪ autosomal-Incomplete-Dominant (A-I-D),
▪ autosomal-recessive (A-R),
▪ autosomal-Poly-Genic (A-P-G)
▪ Sex-Linked-recessive (S-L-R)
Table of primary mutations
Mutation(s)
Varieties
Type
Wild-type symbol (Locus)
Allele Symbol
Dominance Relationship
Dark
Dark Green & Cobalt (single factor D), Olive & Mauve (double factor D)
Structural
D+
D
A-I-D
Blue 1
Blue-series
Colour
b+
b1
A-Co-D with other b-locus alleles, else A-R
Blue 2
Blue-series
Colour
b+
b2
A-Co-D with other b-locus alleles, else A-R
Blue 1 & Blue 2
Yellowface I
Colour
b+
b1 / b2
(Hetero-allelic mutation produced by interbreeding Blue 1 & Blue 2 varieties)
Yellowface
Yellowface II
Colour
b+
byf
A-Co-D with other b-locus alleles, else A-R
Goldenface
Goldenface
Colour
b+
bgf
A-Co-D with other b-locus alleles, else A-R
Crest-Factor (C-F)
Circular Crested, Semicircular Crested & Tufted
Structural
Cr-Locus
A-P-G
Dominant Grey
(Australian) Grey & Grey-green
Structural
G+
G
A-C-D
English Grey
English Grey & Grey-green
Structural
g+
g
A-I-D (rare or extinct)
Anthracite
Anthracite
Structural
An+
An
A-I-D (rare)
grey-factor
Australian recessive greygreen & grey
Structural
ag-Locus
A-R (extremely rare or extinct)
Slate
Slate
Structural
sl+
sl
S-L-R
Violet
Visual Violet (SF Violet Cobalt, DF Violet Cobalt or DF Violet Skyblue)
Structural
V+
V
A-I-D
Dilute
Light, Dark, Olive and Suffused Yellow, White and Suffused White
Dilution
dil+'
dild
A-R
Clearwing (CW)
Clearwing Green (Yellowing) & Clearwing Blue (Whitewing)
Dilution
dil+
dilcw
A-Co-D with dilgw allele,
A-D over dild allele, else A-R
Greywing (GW)
Greywing
Dilution
dil+'
dilgw
A-Co-D with dilcw allele,
A-D over dild allele, else A-R
Greywing & Clearwing
Fullbodied Greywing
Dilution
dil+
dilcw / dilgw
(Hetero-Allelic mutation produced by interbreeding Clearwing & Greywing varieties)
Recessive Pied
Danish Pied, Harlequin
Local-Leucism
r+
r
A-R
Australian Pied
Australian Pied, Banded Pied
Local-Leucism
Pa+
Pa
A-C-D
Clearflight Pied
Continental Clearflight & Dutch Pied
Local-Leucism
Pc+
Pc
A-C-D
Clearflight Pied and
Dark-eyed Clear
Total Leucism
Pc+ & r+
Pc r
A-Co-D
Spangle-Factor (Sp)
SF Spangled (showtype / typical mutation) & DF Spangled (clear white &/or clear yellow morphs)
Total Leucism
Sp-Locus
A-I-D
NSLino
Non-Sex-Linked Ino aka Recessive Ino
NSL Complete Albinism
a-Locus
a*a
A-R (extremely rare or extinct)
German Fallow
(aka Bronze Fallow)German Fallow
NSL Incomplete Albinism
fg+
fg
A-R
Brown &/or Sepia
Brownwinged
NSL Incomplete Albinism
b-Locus
Presumed A-Co-D with only a-Locus alleles, else exclusively/inclusively A-R (extremely rare or extinct)
Faded
NSL Incomplete Albinism
fd-Locus
A-R (extremely rare)
Beigefallow, Palebrownfallow & Palefallow
Australianfallow
NSL Incomplete Albinism
pf-Locus
A-R
English Fallow
(aka Dun Fallow)English Fallow
NSL Incomplete Albinism
fe+
fe
A-R
Scottish Fallow
(aka Plum-eyed Fallow)Scottish Fallow
NSL Incomplete Albinism
fs+
fs
A-R
Cinnamon
Cinnamon
SL Incomplete Albinism
cin+
cin
S-L-R
Ino
Albino, Lutino
SL Complete Albinism
ino+
ino
S-L-R
Cinnamon & Ino
Lacewing
SL Incomplete Albinism
cin+ & ino+
cin ino
S-L-R Occasional (4%) cross-over between Cinnamon & Ino Loci
Sex-linked Clearbody
Texas Clearbody
Partial-Albinistic (Par-ino)
ino
inocl
SL-Co-D with other ino locus alleles, else S-L-R
Blackfaced (BF)
Melanism
bf-Locus
A-R
Darkwinged (DW)
Modifier
dw-Locus
A-Co-D (only noticeably expressive in combination with dil-Locus alleles & most interestingly with Greywinged & Suffused)
Dominant Clearbody
Easley Clearbody
Pigment redistributing
Cl+
Cl
A-C-D
Opaline
Opaline
Pigment redistributing
op+
op
S-L-R
Saddlebacked (SB)
Local-Leucism
sb-Locus
A-R (extremely rare or extinct)
History
In the first few decades of the 1900s, especially in-between World War I and II, the keeping and breeding of the Budgerigar had become very popular all around the world. Consequently, various mutations occurred and were soon established during this period.
Time line
▪ 1870-75 The very first registered sudden captive-bred colour mutations were Suffused Green (aka Dilute Yellow), Greywinged Green and either one of the two types of Lutino (NSLino &/or SLino) mutations. All three occurred in aviaries in Great Britain or Europe. Of these three mutations, only the Suffused Green (aka Dilute Yellow) has survived. The latter was easily reproduced in great numbers and is nowadays very well established. The first Lutino mutation quickly vanished but it was re-established in Europe some time between 1931 and 1933.
▪ 1878-85 The Skyblue mutation suddenly occurred in continental Europe, most probably in Uccle, Belgium. Surprisingly, this variety was not imported in England until 1910.
▪ 1915 Single-Factored Dark-Green (aka Dark-Green) in France (where they were then commonly called 'Laurel' which is the french word for Bay (leaf &/or tree))
▪ 1916 Double-Factored Dark-Green (aka Olive) in France.
▪ 1918-28 Respectively, Greywinged Green and Greywinged Blue appeared in England and continental Europe.
▪ 1920
▪ Crest-Factor in Australia.
▪ Suffused Blue (aka Dilute White) in England and France.
▪ Single-Factored Dark_Blue (aka Cobalt) in France.
▪ 1921 Double-Factored Dark_Blue (aka Mauve) in France.
▪ 1930
▪ Single-Factored Violet-Green (aka Violet Factor) in Australia (and were then 1st commonly called 'Satin Green')
▪ The first Clearwinged Green (Yellowinged) appeared, developed by H. Pier in Sydney.
▪ 1931
▪ Cinnamon in England, Australia & Germany.
▪ An unknown type of Fallow in California, U.S.A. This soon vanished.
▪ The Germanfallow in Germany, recently been genetically classified and identified as the Bronzefallow (aka Brownfallow).
▪ A plum-eyed mutation, similar looking to Fallow mutations, occurred in England. This vanished or at least became very rare. This mutation was most probably the Brownwings, one of the rarest colour mutations of the species.
▪ The first Albino specimens were produced in both England and continental Europe.
▪ 1932
▪ Three Fallow mutations occurred in England which became known as the Englishfallow. In Australia these have been genetically classified and identified as the Dunfallow or Greybrownfallow (aka Australianfallow). The Beigefallow or Palebrownfallow has been classified in South-Africa, but no reference seems to be available on this particular mutation.
▪ The recessive Anti-dimorphic Pied (aka Danish Pied aka Harlequin) in Denmark.
▪ The Australian (aka Banded) Pied in Australia.
▪ 1933
▪ Green Clearwinged (aka Yellow Wing) and Dominant Grey-Factor appear in Australia.
▪ Both the NSL & the SL Lutino gene occurred in England and continental Europe.
▪ Three Opaline mutations occurred. An Opaline Green hen was captured in the wild and sold to S. Terril in Adelaide. It was later-on reproduced and is most probably the ancestor of all Opaline specimens in Australia. Two sudden captive-bred Opaline mutations occurred in England and Holland.
▪ 1934 Recessive grey factor in England.
▪ 1935 The various Yellowfaced_Blue and Goldenfaced_Blue occurred in several locations.
▪ 1939-46 Clearflighted_Dutchpied in Belgium.
▪ 1948
▪ Texas Clearbodied (aka SL-Clearbody) in the U.S.A.
▪ Dominant Clearbodied (aka Easley's Clearbodied) in the U.S.A.
▪ The first Cinnamon-Ino (aka Lacewings) cross-over mutation was produced in Australia.
▪ The first Dark-Eyed-Clear (DEC) variety was produced in Belgium by combining the ADM Pied (aka Danish/Recessive pied) with either one of the two Dutchpied varieties (Continental or Clearflighted).
▪ 1970-74 Single-Factored and Double-Factored Spangled specimens were produced in Australia.
▪ 1975 Saddleback specimens were produced in Australia.
Notes
It is probable that the Greywings mutation survived as the ancestor of all actual Greywings. However, it is possible that the mutation laid dormant in asymptomatic mutant specimens until it was re-established between 1918 and 1925. Blue Greywing specimens were produced later on in 1928.
It is very likely that all Suffused mutation specimens and their varieties are descendants from the first captive mutant specimens. This means that Suffused is the oldest sudden captive-bred colour mutation of the Budgerigar species.