In the lizards that are brown with green spots, co-dominance is being exhibited.
Genes often occur in pairs called alleles. One gene is usually expressed anytime it is present and it is called the dominant gene. The other is not expressed in the presence of the dominant gene and it is called the recessive gene.
However, when two genes are expressed together such as in the case of the brown lizard with green spots, this is a case of co-dominance.
