The Dalmatian Gene

Text and Photos by Anthony Caponetto

History
Dalmatian is one of the first morphs named when crested geckos entered the hobby in the early 2000's.  The founders of the Chips line, a pair of babies I got from a local breeder, were my first crested geckos, which I got in January or February of 2003, if memory serves correct.  At that time, the name Dalmatian was already floating around and was quite popular with breeders.  Within a year or two, it started being described as an incomplete dominant gene, and the term Super Dalmatian started floating around during that period.

Types of Dalmatian Spots

• Black Spots
  The standard black spots that you see on every Dalmatian.  When exceptionally large, you'll hear this type of spot referred to as an ink spot or ink blot, but it's the same thing.

• Oil Spots
  This is a term coined by someone (no idea who) for faded black spots that you see on some Dalmatians.

• Red Spots
  This is a highly desirable spot type that you see on some Dalmatians.  The more red spots in relation to black spots, the more desirable.

• Green Spots
  Something I don't see in my colony as much as the other types, but they do occur occasionally.

Dalmatian Genetics
The Dalmatian gene is a straightforward incomplete dominant genetic mutation. In heterozygous form, you get fewer spots and usually of smaller size.  In homozygous form - the Super Dalmatian - you get larger spots and more off them.

Terminology

• Super Dalmatian
  Homozygous Gene Carrier: Bigger spots, more of them.

• Dalmatian
  Heterozygous Gene Carrier: Smaller spots, fewer of them.

• Non-Dalmatian
  Does Not Carry Dalmatian Gene: No spots, no gene for spots.

Genetic Odds of Offspring

• Super Dalmatian x Non-Dalmatian
  Produces All Dalmatian

• Dalmatian x Non-Dalmatian
  Genetic Odds: 50% Dalmatian + 50% Non-Dalmatian

• Dalmatian x Dalmatian
  Genetic Odds: 50% Dalmatian + 25% Super Dalmatian + 25% Non-Dalmatian

• Super Dalmatian x Dalmatian
  Genetic Odds: 50% Dalmatian + 50% Super Dalmatian

• Super Dalmatian x Super Dalmatian
  Produces All Super Dalmatian

Common Misconception: 
Dalmatian is difficult to breed out of a line.

The Dalmatian gene was first described by Philippe de Vosjoli as an incomplete dominant mutation, which I have the odds posted above.  The lines I work with in my collection, which are all my lines for 20 years or so, all work in this manner.  

I have heard accounts where non-Dalmatians carry the gene, but the reality is that this would be genetically impossible with a gene that has proven to be incomplete dominant.  There is no third spot at that locus (in thee DNA) and a gecko can only inherit one gene copy from each of two parents.  If you have two visually distinct genotypes (Dalmatian and Super Dalmatian), then it's *genetically impossible* for there to be a third phenotype or physical expression of the gene's presence. 

A gecko can only inherit a gene copy from each parent and there are only two alleles located at a particular locus in the DNA. For a non-Dalmatian pair to produce Dalmatians, I would contend that either someone didn't see a spot somewhere on one of the geckos in the pair, or there's sperm retention at play and the female was housed with another male at some point in the past year.   It's either that, or there's an unknown gene at play that looks like Dalmatian.

There are a number of breeders who tend to be very vocal about not wanting to see Dalmatian spots on this or that, or avoiding buying geckos because of spots.  The reality is that, unless you're working with a Super Dalmatian (homozygous), only half of the offspring are going to inherit the gene.  

PRO TIP:
We commonly start a project/lineage with Dalmatian x Non-Dalmatian pairings and then I'll start breeding for Super Dalmatians and non-Dalmatians on generation 3.  I feel like you really need to focus on refining all the other (more important) things before you fine tune something as inconsequential as Dalmatian spots.   I don't want to sacrifice the progress of the group to deal with something as minute as freckles.  That said, I try to avoid producing super Dalmatians in the first generation of any project that we're going to make in a non-Dalmatian version later.

Note: One thing I have seen on a few occasions are Dalmatians that only had spots on their tails...odd, but it happens.  If one of those geckos were to drop their tail, there would be no visible spots left on the gecko.  This could easily lead someone to believe there's a gene present, but not being visually expressed

Photo Gallery
Dalmatian & Super Dalmatian