[Jack Garcia]

They're all so cute! What's up with Marble's markings? It really does look like she's marbled! lol At first glance I thought she might be variegated.

You're right that if a mouse has white a tail tip or headspot or white toes, it probably carries recessive white spotting. Not always, though.

 

[Jack Garcia]

It's true that variegated should be more even, but it never is in petstore-derived stock. I think she could be either or both. The only way you'd know for sure is by breeding her to a mouse who you're 100% certain doesn't carry recessive white spotting. Variegated is dominant.

On my screen, Zigzag (which is a really fun name, btw) looks black.

Do you see how you can almost make out a band around Marble's belly and a white stripe that goes down her spine? Both traits are very common faults in the variegateds I've seen--when the variegation isn't evenly distributed, it tends to "clump" the white spotting in those two places. That's why I first thought she might be variegated.

 

[Jack Garcia]

ya i have notice the slight band and line down the spine. i didnt know what it was though until you said something haha. and i dont have a male that im certain doesnt carry recessive white spotting. mango might not carry it but i dont know because i dont know his parents or anything. maybe when i breed mango with peanu, kiwi, or baby, i can use one of the sons to breed with marble. and ya zigzag does look black on the screen but she is actually lighter and more grey colored in person (so is marble) so thats why i think she is blue. what happens when you breed blue to chocolate?

In general breeding blue to chocolate will produce all black babies who carry both blue and chocolate, unless they share recessives. A mouse who is both blue and chocolate (a/a d/d b/b) is termed lilac. It's a difficult color to get right and can resemble chocolate or blue. The trick is getting it somewhere inbetween.

 

[Jack Garcia]

I would, too! They look like black holes that just suck the light into them and pulverize it! lol

 

[Jack Garcia]

It takes years or decades of selective breeding for only the blackest of the black. Your eye has to be trained to see very minute differences that most people (including most mouse breeders) would never see. In that way, mouse breeding is more of an art than a science. But a lot of the blacks who win prizes (in the UK or US) are actually ae/ae instead of a/a. That helps a lot.

 

[Jack Garcia]

Introducing the extreme gene helps alot these days, more and more people have got the extreme gene i reckon.

I went to a mouse show today and saw a black thrown straight out of its class because it was the wrong 'shade' of black. I'm pretty sure the others it was competing against were extreme.

Willow xx

Yep, it happens. If it's not dark enough all over, it isn't allowed to compete.

I have a sneaking suspicion, though I couldn't prove, that the blacks who aren't ae/ae and who can still hold their own against the ae/ae mice are actually umbrous too (a/a U/*).

This is because some black-based (a/a) PEWs I got from a breeder in California give umbrous babies all the time but you wouldn't know it till you outcross and end up with a non-PEW (usually agouti) baby who is clearly umbrous, which I've done.

haha! man how do people get their black mice to be like that?

My (joking) answer to this is often, "Clairol Perfect 10." lol

 

[Jack Garcia]

The extreme gene, also called extreme non-agouti, is represented as ae and is the lowest recessive allele on the A-locus. It's called "extreme black" or "super black" from time to time. So if a normal black is a/a, an extreme black is ae/ae. You have to have the gene to introduce it and it is unrelated to the extension locus (which uses "e" as its initial and causes confusion with ae sometimes). Since everything on the A-locus (Ay, Avy, Ahvy, Aw, A, at, am, a) is dominant to it, you may have it lurking around in any population of mice and not necessarily know it. Because it causes an overabundance of pigment, mice who display two copies of this gene are slightly smaller than other mice, as a general rule. Just ask any breeder of show blacks--their mice are usually the smallest at any show!

Most good blacks (whether a/a U/* or ae/ae) carry nothing else. This is a very important point to remember. You would never breed a good black to a chocolate or blue or spotted mouse, etc. Black is the only acceptable outcross, period.

Umbrous, represented U, is a gene which only shows some of the time and only on some varieties. It's generally classified as a dominant trait but its dominance is partially modified by the A-locus, which basically means it can be present on an agouti mouse and not show depending on what else is going on. Few people have real umbrous in the US, as all of our umbrous comes directly from English imports. You can read more about umbrous on the Jax (no relation, haha) laboratories website, but I forgot where the exact link is since I lost all my bookmarks recently when my computer crashed...

Edit: Here is a photo of one of my heterozygous umbrous mice, WNT Langlia:

She is argente and the umbrous part of her is dove. Were she agouti, the dove part would be solid black, and were she black the umbrous part would help to make her darker all over. Despite good type (that you can't really see in this picture, she's an old lady), she could never be shown due (in part) to the umbrous.

 

[Jack Garcia]

You're very welcome. I love helping people with mouse genetics.

The only way you'd be able to tell if any of your mice carried ae is by careful breeding of siblings over and over. If the mice have anything else going on at any other loci, it complicates matters because you might not be able to tell even if your mouse is ae/ae. For example, most of the c-locus dilutes (himalayan, beige, albino) show little difference on an ae/ae background as opposed to an a/a background*. One example that Finnmouse gives is ae/ae chocolates. They lack the reddish shade that is required for good chocolates, but you might not know that that's what's up because everyday "poor" chocolates also lack that. Extreme non-agouti is not very common in the US outside of the New England area or LA. You see it almost exclusively at mouse shows.

*This is true up to a point. The best siamese are probably ae/ae ch/ch.