b. The homologous trait for the humans is used for one main reason and that is for moving from various locations in a walking, jogging, or running manner. On the other hand, apes use their feet in various ways. For example, they may use their feet for walking but they also use their feet as the same function of an extra set of hands. They use their feet and are able to grasp food , while humans do not have that ability to grasp objects as well as apes are.
c. Generally, the common ancestor between the human and the ape would be more closely related to the ape or a chimpanzee. Studies have shown that the possible ancestor of the human and ape was possibly 7 million years ago.
d.
2. a. The analogous trait I choose was the eye of a human and an octopus and they are not closely related to each other with relation to common ancestors.
b.The human eye and the octopus eye are used for basically the same reason and that is for vision and sight. Although the structure between the two may be slightly different, the main function is similar to each other.
c. If I was to further investigate way far down the ancestry line between the human and the octopus, there is a high chance that I would find a common ancestor between these two because the majority of organisms have an eye as an organ. In the end, the majority of pairs begin with one common ancestor but that is not to be determined unless you were investigating pairs that existed a long time ago.
d.
Hi Desiree,
ReplyDeleteI always wanted to read a little more about gorillas and humans having the same kind of structure. I also did the octopus eye and human eye, i read something really interesting about humans having a "blind spot" by their optic disk where their is no image detected, the octopus doesn't have this which to me is pretty fascinating :) Great post!!
Hello Desiree,
ReplyDeleteI really enjoyed reading your post especially since I used the octopus and human eye for my analogous trait as well. It was really interesting to learn about how similar our eyes are to these animals since we are so drastically different, and it also caused me to wonder what in evolution caused us to not also develop a lack of a blind spot. Excellent job on your homology traits as well, people so often compare humans and apes so it was cool to look at it from a different perspective.
Okay on your opening description of your homologous species, though this could have been expanded.
ReplyDeleteYou do a good job of describing the differences in function for the human/chimp foot, but how is this difference in function expressed in differences in structure? How does the foot of the chimp differ from the foot of a human to allow for the difference in function?
With regard to ancestry, since both humans and chimps are apes, the common ancestor WAS and archaic ape. Did that common ancestor possess this trait? Why is this important for confirming that these traits are homologous?
Good images.
A little more description was needed for your analogous pairing beyond just identifying the species and the trait you are comparing. This helps your reader better understand the function of the trait.
The eye is a classic example of an analogous trait given that it has evolved independently several times in Earth's evolutionary history. A little more description would of been a good idea on these traits. You correctly identify the similar function, but the design of these two sets of eyes is very different, which helps to confirm that they are indeed analogous traits and not homologous.
With regard to ancestry, given (as explained earlier) that the eye has evolved independently more than once, having eyes doesn't guarantee common ancestry. Additionally, remember that for analogies, the common ancestor cannot have had and passed on the trait to the two descending organisms, correct? If they did that, that would mean these are homologs, not analogs.
So what we need to know here is that the common ancestor did NOT have this trait and pass it on. We have a couple of pieces of information that (for those of us who don't have extensive knowledge of octopi) we can use to confirm this. One is phylogenetic information that confirms that the structure of the octopus eye is genetically different from that of the human eye. The other is the issue of design, mentioned above. The human eye is structurally flawed, in that it has a blind spot at the back of the eye due to the placement of the optic nerve. The octopus eye doesn't have a blind spot as it's structure is completely different from the human eye. This difference in structure is additional evidence that these eye structures didn't arise from a common ancestor. That helps to confirm that these eyes are analogous traits, not homologous.
Good images.
Hi Desiree,
ReplyDeleteGreat species to compare for homologous trait. For part a of 1 and 2, you might have wanted to describe the individual species just a little more. For part b of 2, there are numerous species that have eye that are used for the same purpose as humans. Are human and octopus eyes structured the exact same way? If not, how are they different?