Genetic Updated Studies / About Bengals

The Stanford Medicine team suspected that Bengal cats might give them an accessible way to probe the genetics of wild cat colors and patterns that had evolved naturally. But after sequencing 947 Bengal cat genomes, they found something surprising: There were no parts of the wild Asian leopard cat genomes that were found in all Bengal cats.

"Nearly every Bengal cat breeder and owner has this idea that the distinctive look of the domestic Bengal cat must have come from leopard cats," Barsh said. "Our work suggests that's not the case."

Instead, the genetic signatures suggested that the unique appearance of Bengals was a result of variations in genes that had already been present in domestic cats."

"The team found something similar when they looked specifically at "glitter": About 60% of all Bengal cats have particularly soft, iridescent fur that glitters like gold in the sunlight. A mutation in the gene Fgfr2, they showed, is responsible for glitter and comes not from leopard cats but from domestic cats. Glitter and the underlying Fgfr2 mutation are nearly specific to Bengal cats. Interestingly, the mutation reduces the activity of the protein encoded by Fgfr2, rather than rendering it inactive as many mutations do. This sheds light on how variations in genes can cause subtle changes in appearance, the researchers said."

"Finally, Barsh and Kaelin's group analyzed the genetics of "charcoal" Bengals, a rare subset of the breed with darker coloring. They uncovered a leopard cat gene linked to the charcoal color, but only when it was combined with domestic cat genome. The leopard cat gene, known as Asip, essentially doesn't work as well when it's mixed with the domestic genes - a phenomenon known as genomic incompatibility. So, in leopard cats, Asip doesn't cause charcoal coloring, but the same gene in domestic cats does."

""Hybridization between different species can happen naturally and is responsible for the small amount of Neandertal DNA found in many human genomes," Barsh explained. "But the wild leopard cat and the domestic cat are more different from each other than humans are from chimpanzees, and it's remarkable to see how DNA from these distantly related species can exist and work together in a popular companion animal."

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.

Backcrossing is when an individual from a hybrid population is bred back to one of the original parent types (species or breed). Backcrossing aims to transfer specific traits from the leopard cat to the Bengal population while retaining the desirable characteristics of the Bengal cat. The first cross between a leopard cat and a Bengal is a hybrid; however, every generation after that is a backcross.

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.

BENGAL GENETIC BREAKDOWN

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.

Genetic testing

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 haven't had any experience with any other DNA sites.

InforGenetic Updated Studiesmation Update

https://med.stanford.edu/news/all-news/2024/03/bengal-cats.html

Backcrossing, Hybridizing, and the Bengal Cat

BENGAL GENETIC BREAKDOWN

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