What does the spotted pattern modifier do to the classic tabby pattern, do you have any pictures? I feel like any spotted tabbies I see have patterns that follow the mackerel pattern. Does it look differently with the classic pattern, or does it somehow not affect it or smth?
I think right now there is no real consensus on the interaction of spotted and blotched. For example Kaelin & Barsh vote for "no effect all", and puts down mackerel as the tabby (Taqpep/LVRN) genotype of spotted:
Hartwell (of messybeast) thinks it does affect it, or at least a spotting modifier which does exists: "Spotted tabbies can be due to broken mackerel stripes (in which case the spots are not so rounded) or to a spotting gene. The spotting gene breaks up the underlying mackerel or classic tabby pattern into spots."
Personally, when this topic comes up, I always have to think of bengals.
Look at that curve of spots on the first one next to the spine, and that one long rosette on the next in the same position. I can't help but feel like the lines of the blotched pattern are there. Auh, I don't know. "Every bengal is genetically blotched but some have a spotted modifier thus rosetted" and "every bengal has the spotted modifier but some are homozygous blotched thus aren't affected" are both equally valid and sound models, but something pulls me toward the former.
I found some statistics in the supplementary materials of this paper: the authors tested 16 bengals for taqpep alleles and found one at 0.5 frequency.
...All right, that's a little confusing. 50% feels too much compared to the prevalence of marbled (although they didn't disclose the pattern of the cats, so it's possible they just had that much marbleds and carriers by accident or by choosing related animals), and too little for "every bengal is blotched under the rosettes". Maybe there are more, unkown and untested alleles?
AND WAIT A MINUTE!
"Pattern phenotype of F. nigripes, which resembles the atypical swirled pattern observed in domestic cats that carry the T139N allele (Fig. S2). Nine of nine F. nigripes individuals were fixed for 4 species-specific variants (T82K, H87P, E488K, F950V)." Black-footed cats seem to be genetically kind of blotched and phenotypically spotted! So a blotched-type pattern breaking up into spots is indeed possible.
A few more remarks: famously spotted breeds egyptian mau and ocicat both have a relatively high taqpep mutation frequency here (0.32 and 0.6 respectively). To me this suggest their spotting gene affects genetically blotched cats too.
...And now i looked into ocicats and found they have a sister-breed called aztec with a classic tabby pattern according to GCCF. If ocicat, too, has 60% allele frequency of blotched, that suggests the main difference between ocicat and aztec isn't mackerel vs blotched but a spotting modifier. (What's more, this ocicat breeder says not only the spotted modifier of ocicats affects blotched, but actually the mackerel allele has been completely eliminated from the breed.)
Ocicat. If you want to, you can imagine the blotched "bullseye" into the arrangement of the spots. At least I can 😆
All right, this starts to get long, and i know i won't be able to draw any real conclusions in the end. So.
Blotched is complicated*, spotted is even more complicated**, we don't know.
*several alleles that don't necessarily have the same interaction with spotted;
**probably a mix of different modifiers, and it's very well possible some of them affects blotched and some don't.
