Sara Bearden
October 23, 2014
Evolutionary Relationships Between Animals
Which animals are more related to each other, a pig, horse, dog, cattle, or a chicken? The reason for the investigation on this question is because all the animals beside the chicken give live birth where the chicken lays eggs and that’s where their babies develop. These animals can be seen on a farm which, means that they live in similar environments with each other. With similar environmental pressures they may have more similarities in how their muscle is developed in how it can move. Their common ancestor would have passed down traits that enabled them to live in those condition. For instance, a horse and a dog can run for long distances and can be used for that aspect so, those traits may be similar between them since they use their leg muscles for similar functions. The gene that controls how the muscle moves is myosin. There are many strands of this gene so I decided to focus on only one of the main strands of the gene. I compared heavy strain seven which, is for the cardiac muscle in the animals. The way that their muscles move for their heart may be similar because of the animals body types or how the animal interacts within their environment.
In this investigation I used the programs ClustalX2 to align the sequences and NJPlot in order to create the phylogenetic tree. The sequences I compared were the protein sequences of the gene in each animal. In order to find these sequences I used www.ncbi.nlm.nih.gov/nuccore. When using this website I typed in the scientific name of each animal and myosin and clicked on the result that said their scientific name myosin, heavy chain 7, cardiac muscle, beta. From there on I copied the sequences onto a word document and saved it as a text file and uploaded it onto ClustalX2. The sequences were aligned and then NJ Plot presented the tree for the similarities. I used these programs in order to get accurate information and to have accurate results in my investigation because if I was to do it myself I would of had more errors doing the alignments and comparisons than with a program doing them.
The results after the phylogenetic tree was drawn was that a pig and cattle are the most related animals out of the five. The chicken became my out group since it was the first one to diverge from the common ancestor among the animals. The pig and cattle were the last ones to diverge from the most common ancestor between the dog, horse, pig, and cattle. A horse is more closely related to the cattle and pig than a dog is in this gene by looking at the tree. What this means is that there were less differences in their protein sequences for myosin. The pig and cattle had even fewer differences which, is why they are more closely related to each other than to other animals in the investigation. Based on the evolutionary relationship between the cow and pig one could predict that the movement of their cardiac muscles are very similar to each other since the sequencing for the gene in both have few differences. The function of this muscle is doing similar things in both animals.
There has been research done on the evolution of both the cattle and pig. Both animals were domesticated about 10,000 bp. The domestications occurred in Europe as well. However how these two animals adapted to the new environments from the domestication was different. Cattle had to adapt to environments that were arid or wet tropics depending on where they were taking based on the colonization of the humans. Researches have found that farmers are selecting for certain traits in the cattle like fertility and tenderness of their meat for production reasons, since they have been seeing some “production diseases” like lameness and reproductive disorders (O’Neil 1). Now as for pigs they had different adaptations when they were domesticated by humans. One is that their back elongated the number of vertebrae increased (Groenen 1). This could possibly be due to the demand for the pigs meat, the ones that had longer backs were more favorable to keep around at first so that there were more to have for later and then use for food. Also there are great genetic difference between the pig and their relative the wild boar and that is due to their separation from about one million years ago and being domesticated.
What that research proves is that even though pigs and cattle have similarities in the muscle that controls their cardiacs doesn’t me that they are actually that closely related. Based on the research done these two animals were both domesticated but, were in different environments and they adapted differently to being domesticated. Both did have mutations that allowed them to become more suitable for the environment but, they were different. Cattle had adaptations to become more suited live in the climate they were in where pigs adapted by how they were used. Their backs started to elongate over time because those with longer backs were more desirable for the farmers. They experienced similar environmental pressures that would have lead to similar adaptations to their cardiac muscles to be more related in the phylogenetic tree but, these animals in reality are not that much related. They do not have the same type of bodies and developed in different areas from mutations that made them more desirable for the humans.
In conclusion, my results from the comparing of the seventh strand of the myosin gene in a horse, dog, pig, cattle, and chicken were that the cattle and pig were the most related organisms. The chicken ended up the out group because it was the least related animal out of the five form diverging first from the common ancestor. Even though the phylogenetic tree shows that the cattle and pig are the most related they are not actually that close related in reality. Even though both experienced domestication by humans the animals were used differently which, accounts for why they adapted differently from each other. My results were not as accurate in depicting the relatedness of the animals and if more comparisons were done on the genes then the more accurate result would have occurred. This investigation shows that even if two animals are more related based on one piece of evidence there may be more out there to disprove it which, is why more phylogenetic tests should be done on different genes to show the relatedness of the animals and then compare results to get an accurate result.
Phylogenetic Tree:
https://docs.google.com/document/d/1MZK9-7aAY-R7CZKButImKmD8Aay5AXzsARK65JcNnew/pub
Citations:
Finding out that similar environmental pressures may add onto similarities in how their muscles develop is very interesting. I was not sure if that was possible at first. But after explaining how horses and dogs run similarly for long distance sure does provides some sort of evidence for your statement. Since the cattle and the pig are not as close or similar in reality, but they are in the cladogram, are there any other genes that may add onto the similarity among these two species? But I do agree with your ending statement on how several factors may disprove the evidence of relatedness among species and why it is important to conduct more than one phylogenetic test.
ReplyDeleteDo you think you would ever revisit this idea but with animals that experienced the same ecological pressures?
ReplyDeleteCould you specify on the comparisons that would lead to more a more accurate analysis of their relationship? If you were to do a further study these animals, what would you choose to study and why?
ReplyDelete