Tyrosinase+ Vs. Melanism Questions

Hi, what is the difference between Melanism and Tyrosinase-Positive? I know these are both closely connected, but can’t find anything to go off of. I was going to ask my Bio teacher but I have already asked her too many questions about this stuff haha. @t_h_wyman Do you have any experience or knowledge in this? Thanks everyone!


I’m not totally sure but this thread might help.


Sorry for the slow reply, was on vacation so was not logging in.

T-pos and Melanism are sort of polar opposites. A T-pos animal is one that has a reduction in melanin levels such that people feel they are a type of albinism (they are not, they are hypomelanistic, but that is a much larger conversation). By contrast, a melanistic animal is one that has an over-expression of melanin, giving rise to a much darker animal.

It is not the best example but think of a snow leopard (not actually a T-pos) versus a panther. Both are leopards, one is lacking melanin and the other is over-producing melanin


Super sorry for not responding! Thank you for all the amazing information!

I do have another question though… What is Tyrosinase-Negative then? It seems like T+ and T- would be opposites, but T+ causes a reduction in melanin, but T- also does the same, correct? At least, T- appear to have an absence of pigmentation.

I guess what I am saying is that if T-POSITIVE decreases melanin, would T-NEGATIVE increase melanin? But of course that is not how it works?

I hope that made sense in text and not just in my brain :slight_smile: Thank you!


Good question. The difference is that while T-pos reduces melanin, T-neg removes ALL melanin. So the difference is between having some, at a reduced amount, versus having none at all.

Here is an analogy that might make it more understandable:

Look at the list of ingredients on a can of Coke and you see ‘caramel colour’ listed. Imagine a situation where the nozzle that delivers that colour is clogged and so you only get three drops going in to each can. Now imagine a different situation where the shipment of caramel colour was not delivered so there is nothing being added to the can at all.

In the first situation, you have a T-pos type mutation because the colour is being added, but it is so little that the Coke is not dark like it should be.

In the latter situation, there is no colour to add, and that is why the Coke is not dark like it should be



Ooooh ok! I understand now. That was very educational. Thank you for the information!


Well thank you for bringing up an informational topic! :wink: