Backcrossing, Hybridizing, and the Bengal Cat
February 12, 2023
by Robyn Paterson
The Bengal cat falls into a category of cat breeds known as hybrids, but this label is not scientifically accurate. The confusion this creates can be problematic for the so-called hybrid breeds. Breeds labeled hybrids are, essentially, backcrossed breeds. What is backcrossing? How is it different from hybridizing? Why is the difference significant for the Bengal cat?
Hybridizing versus Backcrossing - What is the difference?
https://quality-bengal-kittens.com/bengal-cat-blog/blog/backcrossing-hybridizing-and-the-bengal-cat
Hybridizing is when two different types of animals (species or breeds) are bred together. Hybridizing aims to combine the desirable characteristics of both types into a single offspring. The F1 Bengal is a hybrid; one parent is a leopard cat, and one parent is a domestic cat - often, but not always - a Bengal. To continue a line of hybrids, both genders must be fertile. F2 hybrids come from two F1 hybrids breeding together. This is not possible with the F1 Bengal hybrids.
The male F1 hybrid between a leopard cat and a domestic cat is not fertile. Therefore, two F1 Bengals cannot be hybridized to make F2s. Thus, F2 and F3 Bengals cannot be created. Backcrossed Bengal males remain sterile until the fourth generation. Even then, fertility can be unreliable at the fourth and fifth generations when too much leopard cat DNA has passed down. Therefore, female F1 Bengal hybrids are backcrossed to fertile domestic Bengal males.
F1 females are backcrossed to a domestic Bengal cat to create the second generation. This generation is scientifically called N1 or BC1. However, this terminology can cause confusion within the Bengal breeding world because N1 or BC1 could easily be confused with F1 creating a misunderstanding of how many generations the cat is removed from the wild species. To keep the generations from the wild species clear, Bengal breeders started using G as an abbreviation for generation. Instead of calling the second generation an N1 or BC1, we call them a 2G for second-generation backcross. 3G stands for the third-generation backcross. At four generations away from the leopard cat, over 50% of both genders are fertile. This is considered the true start of the Stud Book Traditional (SBT) Bengal breed.
The distinction between hybridizing and backcrossing is important for the Bengal cat. When hybridizing, one is maintaining equal parts of both species. When backcrossing, the leopard cat genetics reduce, and the domestic Bengal cat genetics increase with every generation. The goal of the Bengal breed is to create a domestic cat with the appearance of the leopard cat, but the personality of the domestic cat.
How much leopard cat DNA does a Bengal have?
Through Chris Kaelin's recently released research study, we have learned more about the limited number of genes that the leopard cat passes down to the Bengal. The leopard cat's genes are not evenly spread through Bengal DNA. Furthermore, they had passed down at a lower rate than expected, suggesting that there may have been times when only certain types of leopard cat genes were selected to be passed down. Researchers studied the genes of 722 Bengal cats and found that only a few of their genetic regions showed signs of leopard cat DNA. Problems with incompatible genes appear to have limited how much leopard cat ancestry Bengal cats have.
It isn't easy to bring a new leopard cat line down to SBT Bengal. For example, we have one 2G female who did not produce her first litter until she was seven years old. Not every breeder has the patience to work with cats who do not breed quickly; thus, some hybrids never contribute to Bengal cat genetics. This creates a situation where only some leopard cats' genes get passed on, leading to some genetic bottlenecks.
After the F1 generation, some leopard cat genes simply do not pass down. In the study of 722 SBT cats, researchers learned 7% of the Bengal cat genome does not have any leopard cat genes in any of the SBT Bengals. The leopard cat DNA ranged from .4% to 16% in SBT Bengals. The average Bengal cat has less than 3% leopard cat DNA.
Why is all of this important?
As regulations on wildcats spread worldwide, the Bengal cat must be recognized for what it is - a domestic cat. At times the Bengal cat is misrepresented as the genetic equivalent of a liger or coydog because they are called a hybrid breed. Bengals are NOT a hybrid breed. The breed begins with an F1 Hybrid, but after three successive generations of backcrossing to domestic Bengals cats, the offspring are genetically domestic cats. It is important that breeders, owners, and legislators all recognize the Bengal as the domestic cat that it is.
Work Cited
Kaelin, Christopher B., et al. "Ancestry dynamics and trait selection in a designer cat breed." bioRxiv, Cold Spring Harbor Laboratory, 12 December 2022, https://www.biorxiv.org/content/10.1101/2022.12.12.520105v1.full.pdf. Accessed 12 February 2023.
Exotic Colours and Patterns
Please read this link as it has a very basic reference to genetics in general. But also includes information on red as well as information on cinnamon. https://cfa.org/.../2024/02/ColorsPatternsGenetics.pdf
Hi All I'm not going to go into the "normal" colours readily available for people to purchase. Those can be easily seen and identified almost everywhere when searching Bengals. I'm going to "try" to give people an idea of the more unusual and exotic colour/pattern combinations that I have come across and also bred.
My Adonis is one of those more unusual colour combinations in Australia, not saying that he is the only one but from what I have seen there are not too many out there. One of his current offspring to a standard brown has produced a Silver male. So for Silver testing atm this is the best test.
From his current litter with Umbra he has proven that he is a Silver. Silver is classified as a dominant gene meaning, the cat has to be a Silver to be able to produce a Silver.
I know from his DNA test and the above kitten that he is basically a Silver Seal (Snow) Lynx point that carries a double Charcoal gene (which was classified from his DNA test). Which is why he has such a dark mask which contrasts so beautifully with his stunning blue eyes.
A Charcoal Bengal (Apb/a or Apb,Apb agouti genes) is darker than the traditional recognized Bengal colours. The black smokey charcoal colour was particularly seen in early generation F1 and F2 Bengals.
The Charcoal trait is inherited of colour and can be seen in each colour class: browns, Silvers, Snows (Lynx) Charcoal, Mink Charcoal, sepia charcoal) and even blues
I might not always be correct in my analysis of them but I'm only too happy to be corrected.
The Silver Bengal
Yes Silvers are not so rare or unusual. But when added to another colour becomes harder to see and identify. Particularly as there are very few tests available to DNA this colour.
MOST OF MY CURRENT LITTER WITH SHANDY ARE Seal Silver Lynx Charcoals. But the Silver is still very hard to visually see but WHICH WILL BE STUNNING ONCE fully mature
Silver (I, i or I,I inhibitor gense) is more lack of colour. This gene inhibits any warm colours and gives an almost white base coat contrasted with striking dark markings.
The Silver colour was added to TICA championship in 2004 for the Bengal Breed.
Silver cats come in different shades with backgrounds varying from white to a very dark steel grey colour.
Silvers can also be found in any other colour combination: Silver Snow, Silver Charcoal, Blue Silver etc.....
A silver bengal also has:
- As little tarnish (yellow/rusting brown) in the main coat as possible
- A Dark grey to jet black markings
- A black tail tip
- A brick red nose
- Green or golden eyes.
This gene is known as the silver gene and controls the degree of “shading”.
• “I” is the mutant and is dominant.
• “i” is recessive and is the wild type.
• Shading causes the agouti band to be lighter in color.
It can also cause the agouti band to be wider (Wb), so
much so that the agouti ban extends all the way to the
root. The effect is to produce a hair shaft that has a
colored tip in whatever color is determined by the color
genes.
• When the light colored hair shaft is near white, it is
called Silver. When it is a warm cream color, it is
called Golden.
Clouded Rosettes
Clouded rosettes are large, full rosettes that appear to fit together like a puzzle with little spacing (acreage) in between.
Inspired by the Clouded Leopard’s coat, this reticulated spotting has an almost snake-like appearance.
Overview
Bengal cats have complex genetics that result from breeding domestic cats with Asian leopard cats. This hybridization has led to a variety of coat colors and patterns, including the unique charcoal pattern and rosettes.
Origins
- Bengal cats are a hybrid cat breed that originated in the 1960s.
- The International Cat Association (TICA) officially recognized the Bengal cat breed in 1986.
- The breed's name comes from the Asian leopard cat's taxonomic name, Prionailurus bengalensis.
Genetics
- Multiple genes interact to determine a Bengal cat's traits.
- For example, the charcoal pattern is caused by a combination of a domestic cat non-agouti allele and an Asian leopard cat agouti allele.
- Other genetic traits include silver, mink, sepia, lynx, and melanistic (smoke). These are our more common recognised and some of standardised colours although not all of them are currently recognised unfortunately with Australian Associations.
- Breeders and owners can test for alleles associated with charcoal patterning.
- DNA samples can be collected from cats through cheek swabs.
- Photographs of both sides of the cat and any pedigree or registration records can also be included.
The two DNA Testing sites I have had experience with available are: -
UC Davis - https://vgl.ucdavis.edu/ - The University of California, Davis (UC Davis) has several DNA-related facilities and research programs, including the Veterinary Genetics Laboratory (VGL) and the Genome Center. which so far I have been very impressed and happy with in regard to speedy response and authentic results.
Orivet Australia - https://www.orivet.com/ - Which I plus a couple of my friends haven't been very happy with. Problems are too long to get back to you with results. Inaccurate results.
I havent had any experience with any other DNA sites.
BENGAL GENETIC BREAKDOWN
- Bengal cats have a mix of domestic and Asian leopard cat genes.
- The first generation of Bengals, known as F1s, are 50% Asian leopard cat.
- The average Bengal has 3.48% leopard cat DNA.
- The "charcoal" pattern in Bengal cats is caused by a combination of a domestic cat non-agouti allele and an Asian leopard cat agouti allele.