Colour genetics of Archachatina and achatina

[katsumi]

Evil my Marginata were from Martin Goss! Labelled as albinos but I've had a fair few from him (14) and some where pink eyed and some were silver eyed

[katsumi]

Here are some of the young from 2 pink eyed parents (I had sold most of the pink eyed young by this point for people wanting albinos)

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[Evil Angel]

Yes they were called 'Albino Ovum', I corrected him on the fact they were really Suturalis and he changed the label, he also thought that the silvers were the albinos and that the white ones were just weaker snails (hence why he was giving those away free) lol! He was a little surprised when I corrected him about this haha

[katsumi]

Choked on my coffee laughing lol

[muddydragon]

Evil: (re leucistic and spots rather than specific pattern) i think it may well depend on the original skin patterns. I've never owned dark skinned Archachatina but i know dark skinned fulica have a darker eye stalks and line down their backs in the first place. I just can't see it being a case of being acromelanic due to them being exotherms and if that was the case tank temperature would affect the pigment (say it breaks down above 23oC) someone with a cold tank would have mostly all dark coloured snails and someone with a tank around 26oC would have completely white snails. On the other hand you said yours darkened with age? if your tanks were getting progressively cooler then that would make sense. Anyway i think we shall agree to disagree on that point

Katsumi: I will have more babies for sale soon (if the temperature ever warms up!) i'm just a little worried that i'll end up selling so many that most black eyed white type suts will end up being related to my guys if i keep keeping the babies or selling their eggs as i don't really see many others for sale. (as i think was a problem with jadatzi). but thankyou anyway

[Evil Angel]

Most of my normal coloured margies have a dark stripe, so I have thought about maybe a lightening gene, hence why they are all warm-cream not white and why the stripe is still visible, but never heard of a lighting gene before, I also thought that maybe somehow the pigments in the head-stripe were for some reason very easy for Luecistic gene to colour, hence why it's an entire marking rather than just spots, but never seen any example of this in any other creature before so not sure how reliable that explanation would be

[Kitana]

Well I know that you can have complete markings with leucistics like you get with birds and white tigers with the full black stripes and blue eyes, I did see a weird looking snail not so long ago that had these wierd lighter striped I'll try and find the picture but id have to ask permission from owner in case.

[muddydragon]

i think you may mean a "dilution gene" (actually various things) for lightening? i can believe that's going on too having seen many different shades of body colour in the same species of snail.
I think you may have got it kitana
black eyes with white could be leucistic
black eyes with some dark (eyestalks etc) partially leucistic.
(of course there's also a million other things that could be causing this/involved) but it seems a reasonable explanation until we know better

[Evil Angel]

I've seen various Ovums with a pure 'coffee' coloured skin, there are lots of different shades of 'normal' flesh even within the same species, a couple of years ago I even saw first hand what I can only describe as a odd pale-green fleshed Reticulata, normal fleshed retics have light bodies with much darker heads, there are so many colours and variants, it's very difficult to explain them all. It's a shame we can't know for sure though...

[Kitana]

One day maybe in the future Although if you think about it if we get some results from offspring tests with PEW x PEW we may be able to point towards the direction of it most likely being two different sets genes controlling shell colour and body colour, thus pointing to the fact that Jadatzi not being pure albinos as pale shells aren't seen in other snails. It's a different gene to control banding in cepaea than it is to colouring so there's so many possibilities, each one means that something we always thought to be true, isn't. I'm going to email a few professors again and ask for their opinions on the matter.

[Kitana]

The person who owns the weird snail hasn't replied, so I'll just Pm you both the picture, but it really is interesting!

[Kitana]

Although it could just be a disease, birth defect or scarring over a light silver background, I won't know for sure until the person replies

[Evil Angel]

That does look a lot like scarring, but surely the snail wouldn't have actually survived anything like that!! It would fit in with my partial-Luecistic piebald version, but I think the snail should still be white, and (its hard to tell from the pic) I think the flesh is normal colour?? Very interesting, thanks for sending me that! And please let me know if you find anything else out!

[Kitana]

We're so close yet so far away I'll see what the professor says and let you know. If you find out anything either I'd be so grateful to know too

[muddydragon]

intesesting! i was going to say it looks very similar to scarring. could it be a brixton margie?
Survival depends how it got the scars could have been many slight nibbles from other snails as they don't look deep if they are scars.

Maybe snails can get vitiligo?
Or it could be piebaldism.
or a mosaic... (all rare and since it's not seen often could well be reasons)

I think there is no argument that shell and skin colour is separately controlled. but if they are PEW or albino (skin wise!) would be interesting. It would help if everyone kept pedigrees for any snails they breed and pass them on/offer them to buyers so then the colour of offspring can recorded through many generations.

[muddydragon]

IM SUCH A DOPE!!
I've been photographing my margie babies.
In the past the majority of babies i looked closely at had black eyes so i assumed that like their grandparents (2 individuals) and parents/ parents siblings (5 individuals) they all had black eyes too.
NOT TRUE!
just been looking today even my precious sleipnir (oldest baby) has pink eyes how did i miss that??!! So i'm doing the best count up i can to get a ratio but it isn't easy!

[muddydragon]

only counted up for the larger sizes but they are as follows (using BEW for black eyed white and PEW for pink eyed white)

11cm (sleipnir) (1) PEW
8-9cm (1) BEW
7-8cm (2)1BEW 1PEW
6-7cm (4) 3BEW 1PEW
5-6cm (12) 10 BEW 2PEW

so for the larger sizes of a total of 20 individuals it's 5 to 15 (or 1 to 3)

Obviously i've sold quite a few so i don't know what colour eyes they had but they were chosen at random (within the size group asked for) so i don't think it would affect the ratio too much.

[malacophile]

What does it mean when they have no visible eyespots? Are they blind?

[muddydragon]

they have visable eye spots they are just pink rather than black (as in the jadatzis) just like other albino animals can have pink eyes without being blind i imagine the case is the same here it's just the pigment that is missing. Even if a snail was blind it would not be a problem as they have very poor eyesight anyway and mostly use eyestalks as additional feelers.

[tsrebel]

Interesting thread! I've just read it all and my brain is spinning. I don't have anything more than basic biology, and that didn't explain snail genetics
So, I'm trying to sum things up and offer alternative explanations:
What colours vary among snails?
- skin
- shell (basic colour)
- markings on shell
- eyes
(- and skin markings?)

What if they are all controlled by different genes?

And then there is the variations colour on/off and colour faded - for each colour involved.

And so far I'm talking genetics and not environment. I've read in some research on Cepaeas that the environment (forest/plain grass) seemed to determine markings on the shell, seemingly unrelated to genes. This seems to not be the situation for Achatinids, but one could imagine similar correlation? The information that captive snails tend to have a lighter skin colour would suggest this. And if we accept the conclution mentioned about the wild african snails close to humans being white, while the snails in other habitats being dark, it could be related to pollution? But the reason could also be humans eating the dark snails while leaving the white ones (that is the explanation I've read before).
And then the food may also affect the colours (pollution would be in this category). I read the link on axolotls. This reminded me of my A. retics:
"The second kind of albino I will mention is the axanthic albino. It has normal pigment cell migration but is homozygous for the albino gene and the axanthic gene (a/a and ax/ax), meaning it lacks melanophores, xanthophores and iridophores. It is almost white, but becomes yellow with age due to the accumulation of riboflavins from its diet."
So it seems there are variations in albinism.
And now I've probably confused everyone, so I'll stop

[muddydragon]

the variations you mentioned are controlled by different genes although some - such as skin and eyes may be linked.

are you sure the selection in capeas is not that ones less camouflaged in that environment are more likely to get predated so the more camouflaged colours survive, breed and pass on their genes?

Likewise i've heard the explanation of humans eating the dark skinned ones (in africa) and leaving the white skinned ones. So the white skinned ones survive get to breed and hence genes for white skin become more prevelent in the population. even if white skin is recessive it can become the dominant colour. However outside of locations close to humans white skin would be a disadvantage as this makes you more obvious to other predators which may also be less prevelent around human habitations.

The food eating affecting colours would only affect older specimens as they grow so not babies which would reflect true colours. For instance white skinned pink eyed jadatzi (almost certainly albino) become yellowed with age despite being brilliant white on birth. My margies with white skin and black eyes have never yellowed they are still a bright white.

in my margie suts. pink eyed white is recessive to black eyed white so would suggest the pink eyed whites could well be true albinos and it would be interesting to see if they yellow with age. I wondered if the black eyes with white body could be due to carrying a gene for albinoism however if that was the case i would have expected quarter of the babies from my snails to have dark skin. They did not one quarter have pink eyes and three quarters black eyes as expected if pink eyes is recessive. i would guess black eyed white have no pigment distribution whereas pink eyed whites are true albinos and have no pigment production.

What will be interesting is if my ration of 1:3 pink to black eyes continues across all sizes of my baby margies (from different clutches/parentage) if it does it would suggest all five of my adults are heterozygotes (carry one pink eye/ albino gene and one dominant black eyed white gene) However since their parents were both black eyed whites this would seem unlikely, admittedly i only kept five babies from these parents and it is possible by chance all five were hetrozygous even if both their parents were hetrozygous (and almost certainly unrelated so seems unlikely but not impossible) i would have expected 1/4 of those five (yes not possible but go with it so around one) to have pink eyes (none did) 1/4 to be homozygous for black eyes (not carry a pink eye gene, so roughly one again) and half (roughly two) to be heterozygous (carry one BEW gene and one PEW/albino gene) assuming they are diploid. Although by chance i could have got all heterozygotes it seems a little unlikely....

[Kitana]

One of the main problems I had encountered was actually understanding Albinism, I can only refer to albinism in mammals such as humans, so the main problem is still that we haven't a good enough understanding on snail genes to be able to determine this. In humans there are different types of albinism (which I didn't know) different genes affected result in different forms of albinism and contrary to popular belief most albinos actually have blue eyes rather than the red eyes which I associated with albinism. What I had read from NOAH (national organisation for albinism and hyperpigmentation) is that both parents need to have the same type of albinism (same affected gene) to have albino children, otherwise parents who BOTH show albinism WILL have carrier children that DO NOT show albinism, crazy right? but this still doesn't bring me any closer to my original goal as I have no idea what genes snails have lol All I know is that it's very rare that albinism is bred in humans, it's a mutation that is mainly wiped out, but in snails its seems that it is a white gene for it to be so successfully bred. With jadatzis that's usually a 'jade' and a 'rodatzi' pairing right? Jades carrying the white gene and Rodatzis carrying the pale shell, but if neither of them carry the gene for each others traits then how do jadatzis get their white skin and pale shells? Unless .... snails don't have pairs of genes? Maybe they only have one gene to control colour? It may sound like complete poppycock and I'd love for someone to prove me wrong and provide much needed light on the situation lol but I'm trying to include every possible reason at the moment and it's driving me slightly insane haha

[muddydragon]

i think the blue eyes thing is is animals with a coloured iris the pupil itself will be more reddish/pink.

It makes sense if you think (for most genes) there are two copies (in diploids) of each gene one from each parent. So for albinism which is recessive parent one who is homozygous (two copies of the same type of gene) for lets call it gene A albinism and the other parent (two) is homozygous for gene B albinism. the children will have one albino gene A (from parent one) and one normal gene A from (parent two). They will also have one albino gene B (from parent two) and one normal gene A (from parent one). since it's recessive the normal genes will allow any fault from the mutated (albino genes). Of course you then have fun if different genes/chromosomes are turned off and can get a mottling effect.

With the jadatzi this is how they were bred i believe assuming diploidism. I'm using S for dark shell s for recessive yellow shell W for dark skin and w for recessive white skin.

Rodatzi (WWss) X jade (wwSS)

offspring (WwSs) (looks like normal fulica - this is the phenotype that was produced by crossing these two so would support earlier assumptions)

offspirng were then backcrossed producing following genotypes:

WWSS (phenotype: normal fulica) WWSs (phenotype: normal fulica) WWss (phenotype: rodatzi) WwSS (phenotype: normal fulica) WwSs (phenotype: normal fulica) Wwss (phenotype: rodatzi) wwSS (phenotype: jade) wwSs (phenotype jade) wwss (phenotype jadatzi - white skin yellow shell)

so jadatzi X jadatzi produced more jadatzi (white skin yellow shelled offspring). as you said for those from different original jades X rodatzis then different results may have occured when jaditzi X jaditzi occured as the mutation causing albinism may have been in a differrent gene. Also i'm sure i read somewhere that some snails have better genetic repair systems than most and can repair such mutations to reduce the risk of bad mutations occuring and proliferating with frequent inbreeding (as you would expect in slow dispersing species such as snails) so i believe that in the jadatzi this repair system could be in operation with such high inbreeding in the jadatzi population resulting in some jadatzi pairings producing unexpected dark shelled or skinned offspring.

hope that helps rather than causing more confusion...

[Kitana]

The iris is blue but the pupil has no colour, as it's just a hole lol so on photos it comes out red in everyones eyes as what you see is the red color from the blood vessels nourishing the eye, that's why you get the pink in albino irises, it's not actually a colour pink, it's just translucent and the pink is coming from the blood vessels. FFS ... now I've said that it wouldn't make sense that snails have pink eyes for albinism, as their blood isn't red. I'm making this worse lol the more evidence I get the further away from the truth I'm drifting. I don't want to give up. I will find an answer even if it takes me all my life, I just hope some kind person is reading this and will instantly start working on the genetic coding. On another note I have ran out of coffee

[muddydragon]

yes i know it's just a hole but i think the blood vessels are more prominent in albinos as the pigments in the cones/rods are less strong/non existant (i'm not sure though as they're upside down anyway!). It's a reflection of the retina in photos (which in our case is red with blood vessels) but in animals with a tapetum lucidium it can come out different colours (such as green in cats).

Albinos having pink irises can be blood vessels or they can have blue eyes due to tyndall scattering. Blue eyes is not a blue pigment colour it's a cloudy layer that due to the way light refracts through appears as blue hence you can be albino and have blue eyes as it's not a pigment.
The light detection system in eyes relies on pigments if you have pigmentation problems then the pigments in rods/cones may be different. Perhaps (i don't know exactly what pigments are involved without going back over all this again) there are several pigments in the rods/cones or what ever the snails are using for light detection in they eye spot. One of which may be melanin so if they are albino and cannot produce this the other pigment (which may be pink) is the only one seen.

Many of us would love to do what we call blue skies research and study this kind of thing but there's no funding for it, people will only fund you for something if it improves human health or there's money in it (such as crops) or occasionally if it's for the government - global warming studies etc. Finding genes that you don't already know about or have homologues of from other species is extremely time consuming and expensive and in some cases pretty much impossible you need to know what sort of thing you are looking for first. It's not the kind of thing someone can do on the side either due to not only the time and cost required but the ethics and health and safety side, if i tried to sneak one into my lab and run some molecular tests i'ld be in serious serious trouble all animal stuff is extremely well controlled if i decided to sneak say a plant leaf in and copy up one single gene that would be much easier as there's less regulation of these but i couldn't even look at the whole genome of another plant without getting it into my research somehow and the funding body approving. Also of course you'ld have to kill the snails...

On the upside full genome sequencing is getting cheaper and cheaper to the extent that apparently universities can afford them now (even mine!). Molecular research is advancing at a great rate and so is knowledge of genes with the databases increasing in size all the time by the time we're much older it may just be a snap to sequence a whole genome and compare it to other known genes and know everything you could possibly want to know about the organism. So who knows soon we may know