The subject of genetics (the study of genes, genetic variation, and heredity in living organisms) is, to say the least, very scientific by nature. However, in this blog, we’ll attempt to unravel the science in easy-to-understand language.
Summary of genetics
From scientific presentations to sci-fi movies, we’ve all seen pictures of the “corkscrewed ladder shape” with its “rungs” that typify DNA - deoxyribonucleic acid. This constitutes the genes of all living organisms. To make things even more complex, there is also a related RNA (Ribonucleic acid) molecule involved that lends assistance, but we’ll leave that alone!
Chromosomes (always in pairs, one from the mother, one from the father) are just DNA molecules which are thread-like elements in the nucleus of all animal (as well as plant) cells. Each chromosome, made of protein, contains one molecule of DNA. It is this DNA, with its constituent information, that is passed on from parents to each offspring to ensure each type of living creature is unique from the other (except in the case of identical twin/triplet/etc siblings).
The rungs we mentioned earlier come in four “types”, and the information provided by the DNA depends on how these types are presented along the molecule. A simple allegory is Morse code, which depends on the order of dots and dashes in order to interpret a message. Simplistically, the information in three of these rungs next to one another is “read” by RNA to “operate the system”, including genes driving the engine that makes up the body. As mentioned, this is a very simplistic interpretation.
The place on the chromosome containing the required code to put all this into action is always the same and is called a “locus” (a “specific” place) and contains an “allele”, (one of the 38 pairs of “autosomal” “non-sex” chromosomes plus one pair of sex chromosomes), one inherited from each parent. You will also find “communication” genes that will tell the cell when to turn on or turn off other genes.
It is somewhat beyond the scope of this blog to go into any great detail regarding genetics, as this would take pages to fulfil, and you might fall asleep halfway through. So we’ll provide a very brief summary of how genetics relates to Frenchies.
Frenchie size is controlled by six alleles (plus other aspects aside from genetics), with each parent contributing three each. To explain it in very simple terms, many experts see these six as being either positive or negative in value. The bigger the positive sum of the six alleles, the bigger the resultant dog size; the bigger the negative sum, the smaller the dog size.
Also, gene “dominance” (only one gene is required for dominance) and “regressiveness” (two will be needed), terms you may have come across elsewhere in relation to genetics, have to be borne in mind in terms of inherited traits.
Colour, like size, results from the pairing of genes, one from mum and one from dad. You will find that either one dominant or two recessive genes can dictate the resultant colour. It is often also found that colours which dogs carry can often be hidden, only being seen in their offspring.
We see an enormous variety in coat colour, but there are in fact only just two pigments that actually determine the colour of our canines - eumelanin (essentially black) and phaeomelanin (red). It all comes down to genes giving the instructions as to which cells make which, no or a combination of the two colours. The “default” colour depends on genes to modify or dilute it, with genetics in the driving seat as to how the range of these colours is expanded, diluted and modified.
Although there are some 3 billion pairs of DNA with thousands of genes at work, only 8 are actually involved with coat colour.
I hope this somewhat simplistic explanation helps to give you a suitable introduction into how genetics works in the canine world.