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Genetics can be a little tough to get you head around at first but basically it consists of a few simple principles. Very simply put genes can be recessive, dominant or co-dominant. Lets think of a gene as a parent with a pair of hands, each pair of hands can hold and pass a trait and a parent can only pass a trait with one hand at a time. So each child receives one trait from the mother and one trait from the father and therefore the child is left holding two traits, one in each hand. Theoretically each hand takes a turn to pass a trait where multiple offspring are conceived at the same time. Every time traits are passed to a child there are four possibilities.
Only one trait can be visible per gene at a time. So what the child looks like depend on what types of traits the child was passed and is holding in each hand. Recessive Genes Recessive traits are weak, the child needs to be holding two of the same recessive traits in order for that particular recessive trait to be visible. A Dominant trait in one hand will always outshine a recessive trait in the other. A child holding one recessive trait and one dominant trait in the other shows the dominant trait and is termed heterozygous, a hetro or het for short. A child holding the same recessive trait in both hands is termed homozygous and the trait is displayed. Some examples of proven pattern and colour recessive traits are as follows:
Recessive traits are passed to less and less offspring with every generation and are gradually diluted out of a population. Breeding for recessive traits requires the breeding of parents that carry the recessive trait naturally or of breeding closely related animals. Breeding of closely related animals can bring out desirable recessive traits but can also bring out undesirable hidden recessive traits. Dominant Genes Wild type or "normal" genes are dominant. Dominant traits always prevent recessive genes from being visible. Dominant traits dilute recessive traits with each successive generation. Co-Dominant Genes Co-dominant traits show up when the child has the same trait in each hand but also shows up when the child has only one trait in one hand and a different one in the other. The child which holds only one trait looks different to the child which holds both. It is as if the co-dominant trait and the other trait are combined. When the child hold the same co-dominant trait in either hand the trait shows up more strongly and is called a super. Genetics links NERD's genetics pages are very good. Read all four. Peter Kahl reptiles has some useful reading too. Follow the links on the page. If all those punnet squares seem to much work, here is an online calculator for you at Genetics Wizard |
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