Polydactyl Pterodactyls

     So I'm actually not gonna talk about dinosaurs. I am going to talk about chickens though, and that's basically the same thing. Polydactyly is when an animal exhibits more digits in the hand or foot than normal. This is seen in multiple species, like cats, lizards, chickens, and even humans.

     A well known breed that has polydactyl feet is the Silkie chicken breed. They commonly have 1 or 2 extra digits on their feet. There are also quite a few other heritage breeds that showcase this defect.

     One species that many people are aware of for having extra toes is the cat. Normally, cats have five toes on the front paws and four on the hind paws. There are multiple cases where cats have "thumbs" though. Often there are extra toes on the front paws and not the back. There are even two specific breeds that have arisen out of this mutation, the American Polydactyl and the Maine Coon Polydactyl. Jake, a cat from Canada, holds the record for most toes, which is 28. That's 7 on each foot! The extra toes are very helpful for they assist in climbing, hunting, and dexterity.

Mutation=Evolution

     As you can tell from the title, I'll be explaining how mutation is actually hand in hand with evolution. If our genes had stayed the same, had not mutated in any way, we wouldn't even be here. Nothing like it is now would be here. Mutations are an important part of the progress of life. Organisms need to change and pass down beneficial mutations through generations in order to survive. And since this is all very vague, and more of a summary then anything, I'll go over some specific examples of beneficial mutations.

     Granny Smith apples are a very popular and well known fruit. Did you know that it came from a mutation? One of her trees had produced some different type of apple and she jumped on the opportunity to produce more. It has good consumer appeal, and it's pest resistance and hardiness made it a fave for farmers.
      In 1791, a Massachusetts farmer, Seth Wright, noticed that he had very short-legged sheep in his flock. He bred these together and created a new breed, the Ancon breed. The shorter legs made it so they couldn't jump over fences, reduced the lost number of sheep, and increased weight gain since the sheep couldn't move as much as other sheep. This short-leggedness was a mutation.
      The Murray breed of cattle is another good example of good mutation. A farmer noticed that a cow gave birth to a particularly good line of calves. He jumped on the opportunity to profit off of this mutation and therefore created a new, better breed.
     Often, these mutations go unnoticed for generations until eventually the characteristics just dominate the gene pool. Obvious, visual changes are what farmers usually notice. Some examples are the redness of an apple, the white face of a Hereford, the quality of wool in the Spanish Merino sheep, and the smell of a particular type of rose.

     So, in conclusion, beneficial mutations are kept and passed down through natural selection. This is the same way that evolution has worked throughout history. 

Two Heads are Better than One (not really)

     You guessed it! Today we are going to learn about the most famous of mutations, the multiple headed animals. This condition is officially called polycephaly. So far, the highest amount of heads that has been recorded is three heads, so if you see a picture with an animal that has more, it is photoshopped. This mutation occurs when twins, or triplets,  fuse together while embyros. Most of the time, these critters don't survive into adult-hood.

     These are such a rare oddity that, when a multi-headed animal does survive into adult-hood, it is very popular. Most people love to see these creatures and will pay a lot of money to see, or own, them. The Venice Beach Freakshow supposedly has a very large collection of these animals, though most of them are not living. When they do live, they tend to be either snakes or turtles, and in captivity. The reason for this is that two heads just don't work, they get caught on things and fight for control. When there are two functioning brains they tend to "argue," often causing the creature to move in spazmodic motions. There's even cases where the two different heads on a snake try to eat each other. Ultimately, two heads might look interesting, but they are definitely not better than one.

     Polycephaly can occur in any animal species. It has been recorded in snakes, turtles, lizards, cats, cattle, pigs, goats, crocodiles, and many more. Below are a bunch of pictures that can verify this.

Mutation Color Palette

     Color mutations are probably the coolest mutations to look at. There's albinism, melanism, piebaldism, and just too many to properly list them all. I'll be going over a bunch of them in this post so I hope you like these as much as I do.

Albinism

 

     First is the one that everybody is familiar with, albinism. Albinism is when there is a complete, or partial, lack of pigment in the skin, hair, and eyes. This mutation is almost completely hereditary, though there are cases where two non-albinistic parents produced albino offspring. This is very rare though. To the right is a picture of an albino Javanese Starling, situated at an albino animal breeding farm.

Melanism

     Next is the opposite of albinism, melanism. This is when there is an over-abundance of melanin produced in the skin, hair, and eyes. Just like albinism, it's hereditary, though there are cases where the mutations seems random. To the left, a melanistic ratsnake is pictured.

Piebaldism

     Piebaldism is a very unique type of color mutation. With albinism, the cells lack the ability to produce pigment. With piebaldism, the cells have that ability, but it's just turned off. That's why with this mutation there are sections that have color and sections that do not. This is a very rare occurrence though. A plus with this condition is that it doesn't cause the vision problems that albinism sometimes causes. Overall, this is probably my favorite color mutation because it is so unique, and it has occurred in many other species then just the fawn that is pictured to the right.

Heterochromia Iridum

      This is something that most people are aware of, though they might not know that it's called heterochromia iridum. It's a result of different melanin production in the irises, which causes the eyes to be different colors. The most well known type is complete heterochromia, pictured on the left. There can also be sectoral heterochromia, which has only sections of different color, and central heterochromia, which has spikes of different colors radiating from the pupil. Most commonly, a blue eye is there.

Erythrism

     This is something that people definitely haven't heard about. This is when there is an unusually high amount of red pigmentation. This is caused by genetic mutation, though it can also be caused by an animal's diet. Like how flamingos are pink because they have a constant diet of organisms that contain those pigments. The zebra foal to the right is a good example of this when it is a genetic mutation.

Xanthochromism

     Xanthochromism is another uncommon color condition that people probably haven't heard of. It's very similar to erythrism except that it has an unusually high amount of yellow pigmentation. Also like the above mutation, it can be caused either by genetic mutation or diet. The gecko to the left is definitely a good example of this since that bright yellow is not a normal occurrence in the wild.

Mutations: The Good, the Bad, and the Ugly

     A mutation is defined as the changing of the structure of a gene, resulting in a change from the normal that may be passed down from generation to generation. When most people hear the word "mutation" they think of the bad things like two headed pigs or horrible deformities but a lot of really good things come from mutations. In this post I'll be taking about the good mutations, the bad mutations, and the ugly mutations.

The Good

     Many animals in the livestock industry have good traits that come from mutations. A common one that is easy to identify is with sheep. The tendency for ewes to have large litters of lambs can be categorized as a mutation in some breeds. The Booroola Merino breed is especially affected by this. They can have litters of around 3 to 4 lambs on average, which is great for the farmer.

     Another animal that shows positive mutations is cattle. I've already talked about the "double-muscle" mutation, in my previous post, that can supply more meat per cow, which means more money. There's also a mutation in dairy cattle that can be very good for the butter and cheese industry. Some cows have milk that have a higher percentage of fat, which is great for making dairy products.

The Bad

     Although there are good mutations, there are also quite a bit of bad ones. Again, I'll start with sheep. A common mutation among them are jaw defects. This includes underbites, overbites, and a condition called parrot mouth. The teeth stick out with this defect and almost look like a beak. With cattle there's a mutation that increases milk yield, which sounds good until it's known that this mutation also results in embryonic mortality.

The Ugly

     There are bad mutations, which often don't end in mortality, and then there's the ugly mutations, which are serious genetic mishaps that often prevent offspring from reaching adult-hood. A really bad one in sheep is a disorder called Spider Lamb Syndrome. This genetic disease causes defects such as: abnormally long and bent legs, twisted spines, shallow bodies, flattened ribs, and long necks. A good example of this is pictured below. This is almost the same as another disease called crooked tail, which occurs in cattle.

Double Muscle Dynamic

        When one looks up genetic mutations in livestock, one of the first things to appear are the multiple cases of cattle that have double the muscle than they should, though it's really only 20-40% of an increase. This is due to the fact that the myostatin gene, the gene that regulates muscle, is mutated and so the production of myostatin is either blocked or hindered. This also results in an average 10% loss in bone mass and a decrease of fat. 

         Two cattle breeds that showcase this mutation are the Belgian Blue and Piedmontese. With other animals, like mice, the muscle cells enlarge, but with these cattle breeds the muscle cells multiply instead. The distribution of the muscle is also not uniform throughout, with minimal muscle in the neck and more as you move back into the hindquarters. This is very profitable for the livestock industry since more muscle means more meat per cow. This means that farmers tend to breed cows that have this mutation, though there are reproductive issues.

          The main problem with reproduction is that the offspring are very bulky and heavy. In order to get a superior yield, special care and a higher priced diet are required. There are also more veterinary needs to ensure that they stay healthy. There is also a decrease in milk production and fertility and  calf mortality rates are high. Even though Piedmontese beef is held at a special quality and price, the cost to care for them makes it so there isn't much of an obvious profit for these animals. Ultimately, the risk for caring for these animals is up to the farmer and it can either result in great profit or great expense.