Sex, Glitters and Genetics
Today’s guest post is from Denise van Lent, a Dutch biologist specializing in feline behavior.
Genetics is the science of heredity. It is about the transfer of hereditary characteristics from parent to child. Most articles on this topic are technical, tough and complex which doesn’t make it appealing to learn more about it. Complex as it may be, genetics has impact on all living things, including the cat, which makes it very interesting to us. Let’s take a look at the basics and make genetics as fun as possible, shall we?
Genetics: transferring characteristics
Good nutrition, an annual medical check-up and minimizing stress are factors that u cat-owners can control and positively affect our cat’s health. On the other hand, hereditary factors cannot be controlled. Kittens inherit certain characteristics from their parents that affect their health and longevity. Some of these characteristics that influence your cats’ physique or behavior are not visible to us. Stress sensitivity is an example of an invisible inherited trait. Examples of those that are visible to us, are eye color, hair length, texture and pattern of the cat’s coat.
Each characteristic, whether its eye color or hair length, is controlled by things called genes. A gene is a carrier of hereditary information that determines the cats’ appearance, behavior and health. The genes are located within body cells on spaghetti resembling structures called chromosomes. Human body cells contain 23 pairs of chromosomes, a total of 46, while cat body cells contain 19 pairs, a total of 38 chromosomes. Most of the chromosomes are very similar in both males and females regardless of the animal species. However, one set of chromosomes is always substantially different.
Each cat has 18 pairs of chromosomes in their body cells that are similar for both males as females (autosomes) and one pair of sex chromosomes that determines sex (sex chromosomes). Females have two X chromosomes (XX) and males have one X and one Y (XY) chromosome. The father determines the sex of the kitten: through its sex cells (sperm cells) he eithers passes on an X or a Y chromosome. The mother can give only an X chromosome to her kittens through her reproductive cells (egg). When the sex cells come together during fertilization, the fertilized egg contains either two XX chromosomes (one from father and mother). Or an X and a Y (X a mother and a Y from the father). In the first case (XX) a female kitten is born, in the second case (XY) a male.
One pair of genes for each characteristic
Each characteristic has its own specific pair of genes. And that set of genes determines the characteristics of that trait. There are, for example, two different types of genes involved in the hair length. Namely, the gene for “short hair” and the gene for “long hair.” A gene pair for hair length consists of a combination of these two different genes. The following combinations are therefore possible: short haired/short haired, short haired/long haired, long haired/long haired. The combination determines its length. Thus, a male who has two genes for short hair will have a short hair coat. A male who has two genes for long hair will have long hair. But what if you have a short hair gene and one long hair gene? Which gene will shines through depends on which one is stronger. The strongest is called the dominant gene. In the case of hair length, the short hair gene is strongest and thus dominant. A cat that has both the short hair gene and the long hair gene will therefore be short haired.
This long hair kitten must have the gene combination long hair/ long hair
Hair length, color and texture of the coat are traits that are passed on by parent cats to their kittens. The characteristic “long-hair” you have as a parent, or you do not. Only when you have characterized, can you pass on to your children. A shorthaired cat that characterized long-haired does not possess, so it will never be able to provide long-haired kittens.
Gene changes (mutations)
Sometimes genes can spontaneously change. Such a change is called a mutation. This can have both beneficial and adverse effects. For example, all polar bears used to be brown long time ago. Due to a mutation, the coat color of one polar bear changed to yellow-white. Since the yellow-white bears were hard to see, they were more successful in hunting compared to the brown bears. This in turn, meant that the yellow-white bears survived better and reproduced successfully. This mutation was thus very advantageous because a white-yellow coat is less conspicuous in the white area of the North Pole. Because nature itself, or the environment actually determines whether a gene is favorable or not, we call it “natural selection”. Natural selection is the basis of evolution.
Sometimes the mutation alters their physique. These changes can be so striking that cat breeders select for it. This is not always in favor of the cat itself because many of these mutations are disabling, sometimes even deadly.
Some cats have a very special coat. It looks like they are sprinkled with gold dust or glitter. It is linked to few cat breeds such as the Bengal. But even within the breed glitter is not a common feature. So not all Bengal cats have a glitter coat. Glitter is not a standard feature of the cat’s fur, this is also a mutation. Glitter is a mutation that does not affect the cat in a negative way . Due to this mutation the structure of the hair is changed in such a way that light is reflected in a different way. Some hairs lack pigment on the outside which creates a particular reflection of light. Glitter is not a dominant trait so it must be present in both parents.
Behavioral problems are often caused by factors that are under our control. Even if you own a cat that was born sensitive to stress there are methods to teach your cat how to cope better with stress.
Denise van Lent is a Dutch biologist specialized in feline behavior and obesity. She is the owner of the institute for animal welfare and behavior ‘lekker in je vacht‘ which translates to “comfortable in your fur”.