What Color Is My Horse?

Signing Off

2009-09-13T20:32:00.000-07:00

Hello all. Well, I have now experienced a reality check--I no longer have time for all of my blogs. I started this blog when I was out of work and bored, and now that I am back in a job and teaching horse lessons, I just don't have time for everything anymore.

So, THANK YOU from the bottom of my heart for the horse pictures you have all sent me. I know I didn't use them all here, but the fact that you sent them means the world to me. I even got photos from as far away as OZ! YAY!

Overall, I appreciate everyone for the support. If you ever have questions about your horse's color, feel free to contact me. Thanks, and remember: a good horse is NEVER a bad color!

I'm really, really sorry!

2009-08-18T23:00:00.001-07:00

Okay, I PROMISE I'll have my new posts up soon! But, I have a problem with not having enough pictures of cream horses, particularly buckskins, cremellos, and perlinos. I do have enough palominos. If you have any, please send them my way. Thanks a million!

The Cream Gene - Dilute Gene

2009-07-26T21:41:00.000-07:00

While modifying genes modify the coat color over time, the dilution genes dilute the pigment of the hairs and potentially the skin of the horse to a lighter color. The most common and possibly most sought-after dilution gene is the cream gene. The cream gene is what produces palominos, buckskins, perlinos, cremellos, smoky blacks, and smoky creams. When a creme gene is present on a fully pigmented horse, such as a chestnut or bay, the horse's coat is diluted to a lighter gold color. It's mane also is sometimes diluted, depending on the horse's base color.

Cream is expressed in the written form as Cr. CC indicates a fully pigmented horse. When Cr is coupled with a C, the heterozygous form becomes CCcr, indicating the presence of one cream gene and one pigmented gene. The presence of two cream genes would be expressed as CcrCcr. Sometimes this is shortened to CCr for heterozygous and CrCr for homozygous.

The following is a quick chart that explains what you get when a horse receives one or two cream genes. Click for a larger view. To explain the cream gene further, we have split the six cream dilute possibilities into their own separate blog posts: palomino, buckskin, smoky black, cremello, perlino, and smoky cream. A more detailed description is included on each dilute color's blog post (click the color name for its post).

To My Readers

2009-07-20T17:09:00.000-07:00

Sorry that I haven't posted in a while. I have started a new job and am still getting settled with getting my schedule in place. My goal is to make sure I post a new color at least twice a week, if not more. So stay tuned!

I also still need photos! I'm starting on the cream genes next, so I need photos of palominos, buckskins, perlinos, and cremellos! Spotted, sabino, and other modified variations are welcome! Click here for how to send me photos. Thanks!

Gray - Dominant Modifer Gene

2009-07-06T18:55:00.000-07:00

Found in just about any breed, GRAY is a modifier gene that works similar to how a human's hair will turn gray over time. The gray allele, represented in writing as "G," removes the pigment from the horse's hairs over time. The hairs will turn completely white, or the horse will have white hairs with flecks of red or black, known as "flea-bitten gray." However, the horse's skin pigment will not change--the skin will remain dark.

Above is Dude's Bad Lady a gray Tennessee Walking Horse mare. This photo of Lady was taken in the fall of 2005.

This is Lady and her first foal, Stardust, taken in April 2009. In both photos, Lady has grown her winter coat. We can clearly see the differences in Lady's coat that have occurred over time. The dark hairs along her buttocks, thighs and gaskins have been replaced with lighter hairs. Her dapples have become less prominent, and her mane is showing less black and more gray and white hairs.

Here is Glory, a 20 year old Missouri Fox Trotter mare. Glory has a flea-bitten coat covered in tiny black specks.

In this photo, we can clearly see Glory's dark skin and the black "flea bites."

There are two key characteristics that define the gray color. First, a gray horse is never born gray. Gray modifies the pigment of the hairs over time, so it is not active when the horse is born. The foal may start showing gray hairs as soon as it start sheading it's foal coat. The tell-tale signs that a foal is turning gray will be white hairs intermixed with the base color, white rings around the foals eyes, and white hairs on the muzzle. Or the horse might not change color until it's older. I know a chocolate Kentucky Mountain Horse stallion who suddenly turned gray when he was 15 years old.

This is a photo of Silhouette, Glory's filly. She is about 3 years old in this photo. Her color is very typical of a horse that is changing to gray. She still has her dark hairs, especially in her mane and tail.

It is highly possible that Stardust, Lady's foal pictured above, will turn gray. We're already starting to see small white hairs in among the red hairs.

This is a Lipizzan stallion from the 2004 tour of the Lipizzaners in Phoenix, Arizona. This stallion was young--about six years old. He is turning white, but he still has the black hairs in his mane, tail and on his legs.

This Lipizzan stallion is far more advanced in his gray stage. He does not have the flea bites but is instead completely white. Gray is common and is cultivated in the Lipizzan breed--horses that are not gray do not sell for as high a dollar.

The second characteristic is that gray is a dominant modifier gene. It will change the color of any horse, whether it's black, chestnut, bay, palomino, or any other color. It does not affect any white markings on a horse, however, as the white hairs are already devoid of pigment. White markings are also accompanied by pink skin, which also will not be affected by the gray gene.

This is a photo of Blanco that I took at the 2008 Festival of Horses in Scottsdale, Arizona. Blanco played Shadowfax in the Lord of the Rings film trilogy and is currently a part of Imagine - Discover the Magic. This photo clearly shows how Blanco has a white blaze. We can see the pink skin where his blaze would be.

Names for Gray Horses

Here is the list of names I've collected for gray horses. Be sure to contact me if you have suggestions for more!

Alabastar, Alaska, Angel, Arctic, Arctic Ice, Avalanche, Banshee, Blanca, Blanco, Blue Ice, Bright Star, Cameo, Casper, Caesar, Celeste, Chantily's Lace, Cloud, Comet, Crushed Ice, December, Diamond, Dove, Dry Ice, Ghost, Glacier, Glacier Ice, Gossamer, Gringo, Hedwig, Ice, Ice Block, Iceberg, Ice Bright, Ice Capades, Ice Cube, Ice Man, Ice Skater, Ice White, Icicle, Icy, Ivory, Jedi, Lightning, Leche, Luna, Lunar, Milky, Moby Dick, Moonbeam, Moonlight, Moon Star, Mouse, Opal, Pearl, Pegasus, Phantom, Polar, Polar Ice, Powder, Ptarmigan, Quartz, Rabbit, Rome, Salty, Shadowfax, Silver, Silvermane, Snow, Snowbird, Snowbound, Snowfire, Snowflake, Snow Job, Snowman, Snowmane, Snowstorm, Star, Starbright, Starchild, Stardust, Stargazer, Starlet, Starlight, Starshine, Starstruck, Star Studded, Solar Star, Sparkler, Spartacus, Superstar, Sugar, Talcum, Unicorn, Whitefoot, White Knight, White Satin, White Star, Winter, Zero, Zircon

Review:

Gray - a modifier gene that gradually eliminates the pigment from the hairs of the horse, turning the horse's hairs white.
Dominant - the qualities dominate the overall appearance of the horse, no matter what color.
Represented as GG (homozygous) or Gg (heterozygous).
Gray horses are never born gray; the gray coloration comes over time.
A gray horse's skin pigment will not change; it will have dark skin throughout its life.

Thanks to M&M Stables for the photos of Glory and Silhouette and to Charming Pony Parties for the photo of Lady and Stardust.

Brown - Modifer Gene

2009-05-28T00:13:00.001-07:00

The next modifer gene on our list is a color that isn't always recognized by all horsemen. There is also no genetic marker that has been identified for it yet. This color is BROWN.

Above is Seattle Slew*, the Triple Crown winner in 1977. Seattle Slew has had an extremely strong impact on the Thoroughbred racing industry. And he was brown. http://www.seattleslew.com/

A head shot of Seattle Slew*.

Brown modifies the black gene by creating a lighter brown color in the "soft parts" of the horse. This includes the muzzle, behind the elbow, the belly, and in front of the flank, as well as various other areas on the horse. A genetic marker for brown has not been found yet, so it is not confirmed if it is a dominant gene or not. The overall look of the horse will be a light black or brown. Seal brown is a common description for the color, as is light brown. In some registries, however, brown is not necessarily recognized. Many horse owners will mistake brown for black bay when the horse does not carry the agouti gene to make it a bay. The best way to find out if your horse is brown or black bay is to have it tested for the agouti gene.

These are some more pictures of Seattle Slew+. We can see in the winter photograph that Slew's brown color even showed through his winter coat.

The above photos are of Big Brown^, the Triple Crown contender who won both the Kentucky Derby and the Preakness in 2008. Ironically, Big Brown is NOT brown. He's a bay. Brown's name came from his sponsor, UPS, whose motto at the time was "What can Brown do for you?" http://www.ups.com/

Names for Brown Horses

Here is a list of names that would be great for brown horses. Let me know if you have any to add!

Amber, Auburn, Brownie, Brunette, Cake Batter, Cappuccino, Cashew, Chocolat, Chocolate, Cinnamon, Clay, Cocoa, Cocoa Butter, Coffee, Espresso, Fawn, Fudge, Godiva, Hazel, Henna, Hershey, Latte, Malt, Mississippi Mudd, Mocha, Mud/Mudd, Mudslide, Nestle, Nutmeg, Oatmeal, Peanut, Porter, Root Beer, Sepia, Sienna, Snuff, Soda, Stout, Toast, Twix, Umber, UPS, Walnut, Willy Wonka

Review:

Brown - Modifer gene that causes brown coloration in the "soft points" of a black horse.
Potentially Dominant - the qualities dominate the overall appearance of the horse but only if the black allele is also present.
Not recognized as a color by all horse registries.
Not currently represented in writing as genetic markers have not yet been found.
Common names for shades include light brown, brown, and seal brown.

*Photos by Anne Eberhart, downloaded from http://www.whitehorseproductions.com/ecg_basics2.html

+Photos by Tony Leonard, downloaded from http://www.seattleslew.com/.

^Photos from http://horseracing.about.com/od/triplecrown2000/ig/Big-Brown-Photo-Gallery/

Bay - The Agouti Gene

2009-05-24T20:07:00.001-07:00

Now that we know the two base colors that make up all horse genetics, we can start looking at other colors. Many colors are caused by modifiers. Modifiers are alleles that change the appearance of the base color. One of the most well-known modifiers and most identified is the agouti gene, which creates BAY.

The above picture is of Proud Man's Cherokee Chief, aka Maverick, a Tennessee Walking Horse. Maverick is a excellent example of a bay horse. When the agouti allele is present, it acts on the black allele, restricting the coloration to the "points" of the horse. The points are the lower legs, ear tips, mane, and tail. What is left is the original chestnut coloration of the horse. Maverick is considered a mahogany bay because of his very dark red coat color. He also has a star and snip.

This is Ambrosia, a bay Thoroughbred/Trakehner cross.

The bay color is caused by the agouti gene. The agouti allele is expressed in writing as "A." Lowercase "a" means that the allele does not exist. It is possible for a horse to be homozygous for the agouti gene, or AA. In order for the horse to visibly be bay, however, the agouti allele must accompany a black allele. The horse can be homozygous for black and agouti (AA, EE), homozygous for one and heterozygous for another (Aa, EE or AA, Ee), or heterozygous for both (Aa, Ee). In all of these cases, the horse's phenotype will be bay.

If the agouti gene exists without a black gene, the horse will not have the appearance of the black having been restricted to the points. A chestnut horse can carry the agouti gene if one of its parents carried the agouti gene and it happened to be passed on. They can even be homozygous agouti if both parents carried the the gene and happened to pass it on. In writing, either case would be Aa, ee or AA, ee.

The agouti gene is also responsible for creating colors such as buckskin and perlino. More information on those colors is coming soon.

This is Ranger, a bay Tennessee Walking Horse. Note that his eye color is not brown but hazel. There is no genetic explanation for this as of yet, but some genes, such as the agouti gene, seem to carry a genetic marker for hazel eyes as well.

Above are Thunder and Bree. Thunder is a yearling Thoroughbred, and Bree is a Tennessee Walking Horse. Ambrosia is in the background. Bree also carries the tobiano gene, which is what creates her white markings. She is considered a bay tobiano. Obviously Thunder is still in his winter coat. As his owner has only recently acquired him as of this post, she isn't sure if his summer coat is going to be bay or brown (another modifier gene). We'll include more photos as we receive them.

This is Bree. We can clearly see that her legs, although white, still show the black coloration above the white.

Bay comes in many shades, most particularly mahogany bay, blood bay (a dark red color that is lighter than mahogany), light bay (a chestnut shade to the coat), and black or dark bay (a very dark red, very close to brown). There is no genetic difference in the shades; i.e., there is no way to know what shade the horse will be when breeding for bay.

Names for Bay Horses

The following are names I've gathered over the years that seem to describe the bay color of a horse very well. Feel free to respond so we can add to this list!

Ambrosia, Bayberry, Baylee, Bloodstone, Brandy, Brego, Burgundy, Catalina Bay, Cherry, Chianti, Cisco, Cleveland, Frisco, Garnet, Ginger, Jordan, Mahogany, Merlot, Rimrock, Robin, Seabiscuit, Scarlet, San Francisco ("Frisco"), Whiskey

Review:

Bay - caused by the agouti allele, which restricts the black coloration to the points of the horse.
Dominant - the qualities dominate the overall appearance of the horse but only if the black allele is also present.
Represented as AA (homozygous) or Aa (heterozygous).
Shades include mahogany bay, blood bay, light bay, and dark or black bay.

Thank you to Firewalkers Ranch for the photos of Ambrosia, Ranger, Thunder and Bree.

Black - The Other Base Color

2009-05-20T14:36:00.000-07:00

When we consider horse color, we must also think about "the other" base color, BLACK.

Black is a dominant gene, which means that when present, it will override the chestnut gene. The designation in writing is "E". A horse can be either homozygous or heterozygous for black. If the horse received an E allele from each parent, it will be homozygous, or EE. If it only received one allele, it is heterozygous, or Ee. Either way, the physical appearance of the horse will always be black because it is dominant.

This is Tovis Tess, aka "Tessa." Tess is a Tennessee Walking Horse mare. She'd just been bathed when I took these photos. You can see some red hairs in her coat along her barrel and flank. Many times a black horse will have a red tint to their hair. Winter coats can especially have a lot of red in them. It is speculated that this is caused by the red factor, or chestnut allele. However, even homozygous black (EE) horses can exhibit this trait.

Black can be expressed as "true black," "blue black," or "non-fading black" where there are no red hairs on the horse's body whatsoever. It can also be "fading black" or "sun-fading black," where if the horse is in the sun for long periods of time, the tips of the black hairs will turn red. This is especially true in the ends of the mane hairs.

Here's Tessa in the winter. we can clearly see the red in her winter coat.

Here is Tessa with her first foal, a black colt. Notice how both of their coats show red in the setting sun.

This is Tessa's first colt. He looks like he's still shedding his foal coat in this picture. His foal coat had a lot of red and white hairs in it. This is not unusual for a black foal.

For the record, Tessa's second colt was chestnut, and her third was a palomino. This is evidence that Tessa is not homozygous black as she didn't pass on her black allele to either of those foals.

This is Jedi Whitefoot, a 10 year old pony. This photo was taken in May '09, and he is still shedding his winter coat, which is red. Underneath is a slick, black coat.

Here's Sun's Dixie, or Dixie. She showed more hairs that were red in the summer than in the winter. The above photo is of her in the summer, the below in the winter.

A black horse can be tested to find out if it has the red factor, or "e" allele. If it doesn't, then it is considered homozygous black.

Black is not a completely dominant gene, however. There are other color genes that can change the appearance of black, such as bay, gray, champagne, and cream.

Names for Black Horses

Here are some names I've gathered over the years for black horses. If you have suggestions, please post them and they'll be added!

Ace, Ash, Axel, Baghera, Batman, Bentley, Black, Black Beauty, Blackbird, Blackberry, Blackberry Merlot, Black Dahlia, Black Eagle, Blackhawk, Blackjack, Blackstone, Black Widow, Cauldron, Charcoal, Cinder, Coal / Cole, Daredevil, Dark, Dark Knight, Darth Vader, Diablo, Duke, Duchess, Ebon, Ebony, Flint, Gypsy, Ink, Jackson, Jedi, Jet, Jetta, Midnight, Moonshadow, Nazgul, Night, Night Hawk, Nightmare, Night Sky, Nighttime, Nightwind, Obsidian, Onyx, Pitch, Pitchdark, Phantom, Raven, Sauron, Shade, Shadow, Smoke, Soot, Spade, Storm, Storm Cloud, Tar Baby, Tempest, The Count, Thunder, Tungsten, Tornado, Tuxedo "Tux", Velvet, Zephyr, Zero, Zorro

Review:

Black - the other base color of all horses.
May or may not carry the red factor, or "e," depending on whether the horse is homozygous or heterozygous for black.
Dominant - the qualities dominate the overall appearance of the horse.
Represented as EE (homozygous) or Ee (heterozygous).
Shades include blue black, true black, or non-fading black (no red hairs), and fading black or sun-fading black (red hairs).

Thank you to Firewalkers Ranch for the winter and foal photos for Tessa. Thank you also to Krista B. for the photos of Dixie.

Chestnut - A Base Color and The Most Basic Color

2009-05-15T22:41:00.000-07:00

The best place to start when we talk about horse colors is with the base color of all horses: CHESTNUT.

Chestnut (also called sorrel*) is so named because of its gorgeous red-brown shade, just like the fruit of the chestnut tree, actually called the chestnut. Below is Prides Coin Cash, aka "Red Hawk," my husband's 17-hand Tennessee Walking Horse gelding. He is a chestnut with a mixed mane and tail, which means that his mane and tail have strands of many different colors in them. He had just been rinsed off in this photo, so you can see the spots where he's still drying. However, I like this photo because it shows off the gorgeous copper sheen of his coat.

Chestnut comes in several different shades. Some horses have more of a red tint to their coat, some more brown, while others are more orange. Some horses are liver chestnut, which is a dark brown color, the color of fresh liver. There is also chestnut with a flaxen mane and tail, a common color in Tennessee Walking Horses and Haflingers. The mane and tail will be lighter in color, which can be anywhere from a dark blonde to a true white mane and tail. It is believed that flaxen mane and tail is hereditary and is dominant over the chestnut gene. However, the genetic markers for flaxen mane and tail have not been fully researched.

Above is Delite's Queenly Aire, or "Mariah." She is a 14.2-hand Tennessee Walking Horse and is chestnut with a flaxen mane and tail. It took years for her to grown that gorgeous mane and tail!

Mariah was bred to a palomino stallion and produced the above mare, Sonoran Moon, aka "Cora." Cora is liver chestnut with a mixed mane and tail. This is an excellent example of how we can't always predict what shade of chestnut the foal will be when it comes out that color.

This is Snoopy. We could almost call his coat color sorrel*. Notice the extreme mixture of color in his tail.

This little filly is Ruby, well named for her gorgeous, bright red coat.

Chestnut is a recessive gene and is designated in writing as "ee." Geneticists refer to a single e allele as "the red factor." When the horse has two e alleles, then it is homozygous for producing red, aka chestnut. Unless it is bred to a horse with a gene or allele that is dominant over chestnut, then the offspring will always be chestnut. To understand this further, black is a dominant allele designated in writing as "E". When a horse has one E allele and one e allele, it will be black as E is dominant over e. When a horse has two E alleles, then it is homozygous to produce black horses every time it's bred and will never produce a chestnut horse. (Click here for more information about black.) Genetic testing is available to find out if a horse carries the red factor--Click here for more information.

Overall, the best way to describe chestnut is that when no other color gene exists that is dominant, the horse will be chestnut. This makes it the the most basic color for all horses.

* It's important to note that there is no genetic difference between sorrel and chestnut. They are just two different names for the same color. I have heard an explanation that sorrel horses tend to have a more orange tint to their coats, while chestnut horses are more red or brown. However, genetists don't make that distinction, so it's not really a distinction I make either.

Names for Chestnut Horses

The following are names I've gathered over the years that I think are well suited to the chestnut color of a horse. Feel free to respond to this post to add more names to the list!

Auburn, Bittersweet, Blood Red, Bloodstone, Blush, Brick, Burgundy, Brandy, Bronze, Cardiac, Cardinal, Carmine, Cashew, Cedar, Centavo, Cerise, Cherry, Chester, Chestnut, Chili, Cimarron, Cinnamon, Citrine, Clay, Copper, Coral, Crimson, Dahlia, Damask, Diablo, Fire, Firecracker, Fire Fighter, Firefly, Firefoot, Fire Ring, Firestorm, Flame, Flash Fire, Fuchsia, Garnet, Geranium, Ginger, Iced Tea, Magenta, Peanut, Pecan, Pilgrim, Pippi Longstocking, Puce, Raspberry, Red, Red Baron, Redbird, Red Eagle, Redeye, Redford, Red Hawk, Red Heart, Red Hot, Red October, Red River, Red Robin, Red Rose, Redrock, Red Rum, Red Star, Red Wing, Red Clay, Rocky, Robin, Rojo, Ron Weasley, Rosa, Rose, Rose Red, Ruby, Rudy, Rusty, Sanguine, Sardonyx, Scarlet, Scotch, Sedona, Seeing Red, Sienna, Sierra, Tabasco, Terra Cotta, Topaz, Whiskey, Wildfire

Review:

Chestnut/sorrel - the base color of all horses.
Recessive - the qualities recede and are not observed when a dominant allele is present.
Represented as ee and known as the red factor.
Shades include chestnut, liver chestnut, and chestnut with flaxen mane and tail.

Thank you to Peggie B. for the photos of Snoopy and Ruby.

Photos Needed!

2009-05-14T22:10:00.000-07:00

So now that this blog is established, I need photos! Please send me pictures of the horses you have to this email address. Follow the below instructions so I can easily use your photographs.

1. Put HORSE COLOR in the subject line so the message doesn't end up in my spam box.

2. I'll take any sized photo. The larger the better because I can always resize them to be smaller if needed.

3. If you horse has unusual markings or traits, such as blue eyes, hazel eyes, smut spots, etc., send photos of those along as well. For champagne horses, it's great to get shots of their muzzle or skin around the eyes as the freckles are a qualifying trait of the color.

4. If you are selecting photos for this blog, please choose ones that are outdoors in the sunshine, not in the shade or on a cloudy day. This is so we can see the horse's true color and establish exactly what color it is.

5. I will use any photos you send me unless you specifically ask me not to. I don't want to compromise anyone's privacy. I won't use your name, but it would be nice to know your horse's name!

6. If you know the color of the sire and dam, or even have pictures of them, please send them along. If you own a stallion or mare that has produced offspring, pictures of their offspring and information on the horse they were mated to to produce that offspring is even more valuable.

Thanks for all your help!

Introduction to This Blog

2009-05-14T20:17:00.000-07:00

So you've always wanted to own a palomino. Ever since you saw vintage pictures of Roy Rogers riding Trigger, you've dreamed of that golden horse with the white mane and tail.

Or perhaps your dream color is gray or buckskin. Maybe you just love the loud patterns of Bev Doolittle's paintings, or you are captivated by the white Lipizzaner stallions of the Spanish Riding School in Vienna.

If you're like me, you might have wondered where horse color comes from. My curiosity started when I owned my dream horse: a black and white tobiano mare with blue eyes named Apache. I started wondering what caused her loud spotted pattern and whether or not she'd pass on the color to her foal. Why did she have a black and white foal out of a liver chestnut stallion? How will she continue to produce spots?

So I started studying and learned very quickly that horse colors seem extremely complex. However, I discovered that I can break down the information and understand it just by remembering basic biology from high school.

What? That stuff actually can be used in real life? Yep, it can, and I'll explain it briefly here.

When I was in high school, we had a basic introduction to genetics. We learned that genes dictate certain hereditary traits, such as the color of your eyes or hair or why you pick your nose and you friend sucks his thumb.

In humans, animals and plants, genes have two alleles. One allele is inherited from each parent. The sex cells, the sperm and the egg, carry one allele each, and once the sperm and egg meet, the alleles meet up to create the complete gene. Each allele can dictate how a gene is expressed, or genotype, which is the set of alleles for a specific organism. This dictation creates a trait, or phenotype, which is the observeable traits of an organism (blue eyes, or palomino coat).

Genetic studies concerning hereditary traits was extensively studied by Gregor Johann Mendel. Mendel focused on studying pea plants. Pea plants have two different colors of flowers: purple and white, with no intermediate color (such as lavender). Mendel discovered that when he controlled which colors mated, it was clear that color was being controled on a genetic level. White mated with white always produced white, while purple mated with white sometimes produced purple and sometimes produced white. The kicker was that when he crossed purple and purple, it created purple 75% of the time and white 25% of the time. This means that purple is the dominant color. This also means that it is the dominant allele, which means that whenever it is present, the flower will be purple no matter what.

Mendel also discovered that when two purple alleles were present, the flower was homozygous for purple, meaning it would pass on one purple allele each time. If one purple and one white allele were present, the flower was heterozygous for purple, meaning it might pass on the purple allele or the white allele. The white allele is recessive, which means that when the dominant gene (purple) is not present, the color "recesses" back to the basic color, which is white.

This is a chart that shows how genes work in the pea plant (downloaded from Wikipedia.org). To use the chart, we put the male flower on the top and split his alleles into two columns. The female flower goes on the left and her alleles are split into two rows. The capital letter "B" represents purple--it is capitalized because purple is the dominant color. The lowercase "b" represents white and is lowercase because it's recessive. (To wit, all alleles are represented in writing with a capital or lowercase letter, depending on whether the allele dominant or recessive). When we cross two heterozygous purple flowers, expressed as Bb, then we have the chance of four types of offspring. One will be a homozygous purple flower, two will be heterozygous purple flowers, and one will be a white flower. The phenotype of the flowers will be 75% chance of purple and 25% chance of white.

We can change this chart if we wanted to. Try changing the chart to represent a homozygous flower, BB, with a heterozygous flower, Bb. You will discover that the flower will always appear purple, but you have a 50% chance of it being homozygous purple and a 50% chance of it being heterozygous purple.

Since Mendel's time, geneticists have discovered that we can look for certain markers on the DNA chromosome sequence to learn if a human, animal or plant is homozygous for a trait. This is very valuable in being able to predict life-treatening conditions. For example, a test is available to find out if a horse can pass on HERDA or Lethal White Syndrome. This can help us keep from breeding horses with serious medical issues that could or do kill them. It can also help us to learn if a horse is going to pass on a certain color or not.

That's where this blog comes in. We can turn to genetics to study how horses produce certain colors. I find that it's fun to discover how horse color works. I hope it is interesting and fun for you as well.