Pleiotropy

Two variants of the agouti gene: yellow on the left and a wild type on the right

Pleiotropy is a consequence of genetics that many people are not aware of. Specifically, this is when the most obvious characteristic caused by some genetic variant is not the only trait that is caused by the gene. Frequently, these characteristics seem like they would be completely unrelated, but it is surprising how many examples there are of vastly different traits being due to a small change in an organism's genetic code.


My three mice: Pepper (black piebald longhair), Poppy (black piebald, wild coat), and Ginger (lethal yellow satin)

Ginger before her weight gain

In May I brought home three fancy mice, having wanted to own a small mammal for quite some time. I chose my trio or females from their litter based on who came to me first, so it's just chance that I brought home a dominant yellow. Dominant yellow is also known as lethal yellow due to embryos that are homozygous dominant becoming nonviable very early in their development. As I only had very cursory knowledge of the amazing amount of variation in fancy mice before bringing my three home, I did not find out some of the interesting pleiotropic effects of the lethal yellow gene until I noticed something that distressed me. While her sisters were maintaining healthy body weights, my yellow looked very fat in comparison. After weighing them, I was surprised to find that, while her sisters were in fact right at the ideal thirty gram weight, my yellow weighed a whopping forty grams.

Lethal yellow is a gene that has been used rather heavily in scientific research. Why? Along with the golden coat, this form of yellow causes obesity, insulin-resistant diabetes-like traits, and an increased likelihood of developing tumors, among other things. Understandably, this has lead to lethal yellow lab mice being used in the research of diabetes. Interestingly enough, unlike some other mouse colors, dominant yellow had existed among fancy mice for a very long time, their usefulness for research only discovered some time later.


At first glance, most people would look at a dominant yellow mouse and say, "Isn't that pretty!" without having any idea of what else that color means. If I had previously known what this color meant, I might have decided against bringing my lethal yellow home. In all likelihood, she will live a shorter life than her sisters due to the pure chance of her being born a dominant yellow. 

Thanks to its blue eye, this cat is probably deaf in one ear.

In cats, one of the most prominent examples of pleiotropy involves dominant white. This gene, like lethal yellow, covers any other color that the animal would have. It is also inherited independently from the other white genes found in cats, which cause the tuxedo, van, and "cow cat" patters, among others. Dominant white causes an overall increase in the likelihood of the animal being deaf, but deafness is seen more often in individuals with at least one blue eye. With only one blue eye, the deafness is usually in the ear that is on the same side of the head as the blue eye. When both eyes are blue, it's highly likely that the cat will be deaf in both ears.

The white spotting genes (causing tuxedo, etc.) also can lead to deafness, but this is not seen as frequently as deafness in dominant white cats.

There are countless other instances of pleiotropy out there, some of which have not been confirmed through research. Correlation implies pleiotropy, and many genes correlate with secondary traits.

Sources are Genetics, North Dakota State University, PubMed, University of Tennessee at Knoxville, Genetics (second article), Berkeley, Louisiana State University, and MessyBeast. Images are from Wikimedia Commons with the exception of the photographs of my own mice and are under Creative Commons licenses: 1, 2.

Invasive Species: Cat

Felis catus, a popular pet. This one is feral.

Yep, the common house cat is an invasive species. You may ask, "how so?" Well, cats are actually incredibly destructive creatures because they hunt and kill wildlife. So, every feral cat and every domestic cat that is either kept outside or allowed outside puts many local species in great danger. These cats have helped lead to the decline or possibly even the extinction of many species. Cats are now on the list of 100 World's Worst Invasives at #38. The similarly sized wildcat species of Africa, Europe, and Asia are not included in this, even though the domestic cat is believed to have been domesticated from the African wildcats. 

A sparrow that died by this pet cat's jaws

Introduction was either caused by shipping traffic, as ships often kept cats to keep the rat populations down, or through pets. Many people would bring their pet cat to a new location and then either leave it behind or let the offspring go free. Feral cats are a serious issue in areas such as Australia, where they have a major impact on such species as the red-tailed cockatoo (Calyptorhynchus magnificus) and burrowing bettong (Bettongia lesueur). Their impact is greatest on islands, where species have often adapted to life where there are no natural predators. Many areas will have feral cat colonies, including my neighborhood and the campus where I earned my Bachelors degree.

If you have a cat, there are several common suggestions to help protect wildlife, which include having the cat wear a bell and keeping it in at night. However, studies have mixed results as to whether these are effective methods. When it comes to feral cats, management methods are quite different, and are most aggressive where they pose the greatest danger to native species.

The danger to wildlife is part of the reason why the cats I currently live with are not allowed outside at all. Ginny was a feral-born cat and she would do anything to avoid being outside ever again. Here's another reason to never let your cat outside: indoor cats generally live between fifteen and eighteen years. Outdoor cats, on the other hand, only live an average of less than three years. When we adopted Ginny, she was skinny, very sick, and her growth was stunted. In my opinion, just as you should never feed wildlife you should never feed feral animals either. It makes their population explode, they lose their fear of people, and they become dependent on the food. This can lead to a lot of suffering as well as potential danger to people if the food supply stops.

Images are from Wikimedia Commons under creative commons licenses: one, two

He Drowned the Mouse

I did it. What's it to ya?

The toy mouse, that is! I went to the dentist earlier today, and when I came back I found this.

This is Albus. He's a mix of who knows what with the most beautiful coloring. He's also cross-eyed. He does things like this on occasion. He's very vocal, and when he "kills" the mouse, he'll wander around the house with it in his mouth meowing at the top of his lungs. I wonder if this happened when he was doing just that and got thirsty, dropping it in the bowl in the process. This is not the first time he's done it, so who knows?

Albus is a very quirky cat. He's the sort of animal that will rub against your leg, and then turn around and bite your ankle. He is quite large, and when he decides to beg for food, it's not unusual for him to rear up on his hind legs and put his paws on the counter to get closer to whatever you have. He never jumps onto the counter, though. He has a jump height maximum which is just over the height of our bar stools, and just under counter height. He's about fourteen pounds and that's with him a bit skinny (he's gaining it back quickly). He had to be hospitalized recently for a urinary tract infection, which is why his front leg is shaved and also why he's a bit skinny right now.

His favorite things are dog food, cheese crackers, meowing at nothing, and annoying Ebon.

Training A Cat

If you wanted to start training your cat to do tricks, most people would probably tell you that you are crazy. Cats are too independent, too aloof, that sort of thing, and that it will never work. In fact, training a cat can actually be rather easy. You just need to know how to work with them. Cats are very intelligent, and they're unlikely to start doing things for you unless there is some sort of incentive. It's a "what's in it for me?" sort of mentality. So, if your cat really likes food it will make training them much easier. They're aren't like dogs, who will often do absolutely anything just to get a simple pat on the head.

My cat, Albus (a fluffy flame point mix with white on both his legs and face), knows several commands. I haven't spent a lot of time training him, but he knows Sit, Up, Stand, and Jump Up and will do all of them happily. He's especially good at sitting on command, and will do so instantly without the lure of food. I really must get a video. If I can teach him, an often grumpy curmudgeon, I'm sure that anyone else can train their kitty too. Here's someone who has taught their cat even more:

If you want to start training your cat, here are some things to remember:

1. Find some sort of treat that your kitty adores. Something small, so that you can give a good amount without over-stuffing him or her. 
2. Figure out how to shape the trick you want to teach them. Techniques that work on dogs usually work equally well on cats.
3. Work in small sessions, since cats have small stomachs and also can lose interest quickly.
4. Consider implementing a clicker, as clicker training will help him or her pick up the behavior more quickly.
5. Most importantly: make it fun! 

With some patience, your kitty should be able to do tricks too. 

Of course, I must mention my other cat, Ginny (a semi-feral dilute tortoiseshell). I dad make an attempt to train her as well, but it did not go very will. However, I chalk that up to her somewhat feral nature. When I tried to lure the sit she would give me a wary look and walk away. Usually, luring sit works the first time, if not soon after, and several attempts have all ended in failure. Since I don't want to stress her, I will be leaving my training to Albus.