black panther jaguar
Science

Melanism in Big Cats: What Makes the Black Panther Black?

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Black panther jaguar
Black jaguar – Image by katerinavulcova from Pixabay

A couple days ago, my friend texted me while they were looking at a black panther exhibit at the art museum and asked me what kind of cat black panthers actually are. I had to break it to them–and now to you–that there really isn’t any such thing as a black panther. The name “black panther” is applied to individuals of several species of wild cat which are all black due to a rare genetic condition called melanism. Most black panthers are actually leopards or jaguars, both of which are normally yellow with black spots [9].

What is melanism?

Graphic showing which felids can be melanistic
Many cats come in black [4]

Melanism is a rare genetic mutation that causes animals to have black skin and fur/feathers/whatever when members of their species typically do not [1, 3, 4, 7, 9]. The mutation causes the affected animals to produce an excess of the dark color pigment melanin [1, 2, 7]. Lots of animals can be melanistic, including pigs, cows, mice, butterflies, snakes, lizards, and snails [2, 4, 7]. Melanism is more common in felids than most taxa, however [1-3, 7]. 15 of the 40 species in the genus Felidae are known to exhibit melanism [4].

Melanistic cats have black fur all over their bodies but may still have some of the patterning or their “normal,” or wild-type, brethren. For example, black leopards still have rosettes which are even darker black [7, 9], and some melanistic Asian golden cats have a white mark on the underside of their tails [4].

Melanism mutations have cropped up at least eight separate times in the cat family tree [3]. These different mutations don’t all work exactly the same way. Mutations in the ASIP gene are recessive, meaning that a cat has to inherit the mutation from both parents to be black [2, 7]. The ASIP protein normally inhibits eumelanin (dark pigment) production, and these mutations make the ASIP protein non-functional [2, 7]. Leopards and Asian golden cats inherit melanism as a recessive ASIP mutation [2, 3, 6-9].

Mutations in the MC1R gene are dominant, so a cat can inherit either one or two copies of the mutation to be melanistic [2, 7]. MC1R promotes the production of eumelanin, and the mutations increase its activity [2, 7]. Jaguars and jaguarundis inherit melanism as a dominant MC1R mutation [2, 9].

How many black panthers are there?

In general, the rate of melanism in the felid species that have it is thought to be around 10% [3, 9]. However, the actual percentage varies widely depending upon the species and specific population [1, 3, 4, 8]. Leopards range throughout Africa, up through Asia, and as far north as Siberia. In Africa, they are almost never seen in their black panther form, but in Malaysia, the exact opposite is true–almost all leopards are black [3, 4, 7-9]. Southeast Asia in general has about half melanistic, half wild-type leopards [3]. Servals are more likely to exhibit melanism in the East African highlands and the Tsavo ecosystem of southeast Kenya [1]. While most species have fewer melanistic cats than wild-type, 80% of jaguarundis are melanistic [2, 4].

Melanistic (A) and wild-type (B) tigrinas [4]

It’s difficult to get an accurate count of how many wild cats there are in the world to begin with, due to their stealth and dwindling habitats. Counting black cats has its own particular challenges. Sometimes reports of a “black panther” are ambiguous or a case of mistaken identity [5]. There is still debate about whether or not melanistic cougars actually exist for that reason [5]. Because melanistic wild cats are rare in most environments, people are more likely to take notice of them and tell somebody if they see one, possibly inflating their numbers [1].

Why are only some big cats melanistic?

The evolution of melanism in felids is still up for discussion among biologists. The most prominent theory is that melanism is so common among cat species because it helps camouflage them in dark, forested places [3, 8]. As ambush predators–and sometimes prey for bigger animals–most cats specialize in stealth, so camouflage is important. This would explain why melanism is more common in cats in jungle habitats and very rare in open grasslands where a black cat would really stand out [3, 8].

Researchers have found some other possible benefits to being a black panther, too. Dark coloration may aid in temperature control in high-altitude or cool, moist forest environments [1, 9]. Research in dark-colored birds has shown that they are resistant to feather-degrading bacteria [3], so there is a possibility that melanistic felids have some additional immunity to disease [3, 8].

There may be some downsides to that glossy black coat, however, even in favorable habitats. Black leopard pairs have smaller litter sizes [6], although the melanism mutation itself appears to have no ill effects [7]. Graipel et al. found evidence that melanistic cats in some species may have a disadvantage in communicating with their peers because the lack the white spots behind their ears or on their tails characteristic of their species [4]. Wild cats use these spots to send signals to each other at short distances, silently, without alerting prey or predators [4]. This is more important for some species than others, depending upon their habitat and whether they are more active when it’s light or dark [4]. Some felids don’t have these spots at all [4]. So it’s more advantageous to dress in black for some cats than for others.

Miniature black panthers

One of the felid species that exhibits melanism is the domestic cat, Felis catus [7]. That’s right, you might have a black panther of your very own! Not all black housecats are melanistic, however, because coat color genetics are complicated. Melanistic cats will be solid black, absolutely no white hairs, and their skin will be black as well. Also, fun fact: melanistic kittens often have “ghost” tabby stripes that typically fade with time, like the black leopard’s shadowy spots [7].

Sources

  1. Adkins, B. (2019, May 12). Melanism in servals. Sheldrick Wildlife Trust. https://www.sheldrickwildlifetrust.org/news/wilderness/melanism-in-servals
  2. Eizirik, E., Yuhki, N., Johnson, W. E., Menotti-Raymond, M., et al. (2003). Molecular genetics and evolution of melanism in the cat family. Current Biology, 13(5), 448-453. https://doi.org/10.1016/S0960-9822(03)00128-3
  3. da Silva, L. G., Kawanishi, K., Henschel, P., Kittle, A., et al. (2017). Mapping black panthers: Macroecological modeling of melanism in leopards (Panthera pardus). PLoS One, 12(4), e0170378. doi:10.1371/journal.pone.0170378
  4. Graipel, M. E., Bogoni, J. A., Giehl, E. L. H., Cerezer, F. O., et al. (2019). Melanism evolution in the cat family is influenced by intraspecific communication under low visibility. PLoS One, 14(12), e0226136. https://doi.org/10.1371/journal.pone.0226136
  5. Hartwell, S. (n.d.). Mutant pumas. Messybeast. http://messybeast.com/genetics/mutant-pumas.html
  6. Robinson, R. (1970). Inheritance of the black form of the leopard Panthera pardus. Genetica, 41, 190-197. https://link.springer.com/article/10.1007/BF00958904 [Abstract]
  7. Schneider, A., David, V. A., Johnson, W. E., O’Brien, S. J., et al. (2012). How the leopard hides its spots: ASIP mutations and melanism in wild cats. PLoS One, 7(12), e50386. doi:10.1371/journal.pone.0050386
  8. Sunquist, F. (2006, December 1). Malaysian mystery. The National Wildlife Federation. https://www.nwf.org/en/Magazines/National-Wildlife/2007/Malasian-Mystery
  9. Zaccaria, J. (2019, October 28). Wild cats 101: Black cats and more on melanism. Panthera. https://panthera.org/blog-post/wild-cats-101-black-cats-and-more-melanism

Published October 8th, 2023

Science

Coat Color Genetics

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Five tabby kittens
Colorful kittens – Photo from Pixabay

I majored in genetics as an undergraduate, so whenever I see a cat with unusual patterning or coloration, I can’t help but wonder what molecular wizardry made that possible. Cat fanciers have long wanted to unlock the mysteries of feline traits. While breeders began to puzzle out the patterns before DNA was determined to be the blueprint of heredity, there are still some mysteries to be solved. However, the more obvious traits have been mapped onto the feline genome, and there are even DNA tests for breeders or uncommonly curious pet owners who want to know what genes their cats carry. Today I want to cover the basics of coat color genetics, but I’ll start with a quick overview of genetics so no one gets lost. Feel free to skip it if you know you don’t need it.

Genetics: A Primer

DNA (deoxyribonucleic acid) is the molecule on which all the necessary information to build an organism is stored. Each unit of storage in the DNA is called a gene, and genes code for proteins. Proteins serve an incredibly wide variety of biological functions in the organism, including providing structure and metabolizing food into energy. There can be multiple different versions of a gene in the gene pool of a species. These different versions are called alleles.

Because an individual inherits half of their DNA from each of their parents, they have two copies of each gene. There are species for which this isn’t true, but it is for most vertebrates, including cats and humans. So each individual should have two copies of every gene, with a notable exception that we will get to later, but some alleles are dominant to others, so not every allele will be expressed. In the case of simple dominance, dominant alleles will be expressed if they are present. However, if the individual has inherited a recessive allele from both parents, they will express the recessive trait.

If you’re confused, I recommend looking up a more thorough overview of basic genetics before proceeding. There is much more to be said on the point, and I will do my best to explain as I go along, but it is only going to be more complicated from here. Now, let’s talk about what makes cats so very colorful!

Tom and the Monochromatic Fur Coat

Cats have two coat color pigments: eumelanin, which is black or brown, and pheomelanin, which is red or yellow. The primary coat color gene produces eumelanin. There are three alleles. The dominant allele, B, leads to black fur. The b allele is recessive to B and produces less pigment, leading to a brown coat, sometimes called “chocolate.” The b1 allele is recessive to both B and b, and it leads to a light brown or “cinnamon” coat.

The pheomelanin gene has a dominant allele, XO, that produces a red/orange coat color instead of or in addition to the color at the black/brown locus. The recessive allele, Xo, produces no reddish pigment. The pheomelanin gene is different in that it is located on the X-chromosome. In mammals, females have two X-chromosomes and males have one X and one Y, with some exceptions because biology is complicated.

So tom cats only have one gene for orange pigment, which they inherit from their mother. That is why toms are either ginger or black, but only very rarely both. But she-cats can have a XO and a Xo allele, causing them to have patches of both orange and black. This pattern is called tortoiseshell, or calico if they also have white patches. Tortoiseshell and calico toms can be born if they have two X-chromosomes and a Y or a similar chromosomal anomaly.

White cat with plush cow
White cat with odd eyes. Also a cow. – Photo by Samson Andreea on Pexels

50 Shades of White

White patches are due to the piebald spotting gene, where the recessive, s, allele codes for no white. If a cat has just one dominant allele, S, less than half of their fur will be white, and the white patches are often restricted to the feet, face, chest, and underside. If they have two dominant alleles, more than half of the cat will be white. It’s possible that they may even be completely white.

There are two other ways that a cat may be white, genetically speaking. The dominant white gene, as the name suggests, produces solid white cats with at least one dominant W allele. These cats are likely to be deaf, especially those with blue eyes and odd eyes. Those with odd eyes tend to be deaf in the ear on the same side as the blue eye. Rarely, white cats may be albino. There are two alleles that cause albinism, both recessive and both defective versions of the allele coding for the tyrosine enzyme. Cats with two c alleles are true albinos and have a translucent white pelt with pink eyes. Two ca alleles produce a white coat with pale blue eyes. There is no association of deafness with albino cats.

A Dilute Shade of Pale

The dilution gene is capable of modifying the appearance of other colors. The dominant allele produces the normal coloration. Two recessive alleles causes the pigment granules to clump in the hair shaft and leave large areas without pigment. The result is a lighter, or diluted, coloring. Black cats become grey, known as “blue” in the breeding world. Chocolate becomes lilac, cinnamon becomes fawn, and ginger, or “red,” becomes cream.

This covers the basics, although certain breeds can have unique alleles, such as the amber allele at the orange locus in Norwegian Forest Cats. I will cover the genetics of coat patterns another week. Until then, enjoy this picture of my gorgeous blue-cream calico.

Published February 20, 2020

Updated June 20, 2022