Homologous:
a. A human's tailbone and a monkey's tail are examples of homologous traits. A human's tailbone is a small bone located in the rear end of the pelvis area within a human's bone structure. A monkey's tail hangs at the rear end of the monkey and can be controlled as if it were an extra limb.
b. A monkey's tail is a collection of small bones that extend out in a structure similar to the human spine from the backside of the monkey. This tail serves as an extra limb to monkeys and is used to help swing for tree to tree and keep balance. A human's tailbone serves no real purpose. It is similar to the tail in a sense that it exhibits the same bone structure that the start of a tail has. The difference is that in a human's tailbone, the rest of the tail is not there. It is just the single bone. These homologous traits exhibit differences although they are closely related because of the lives that each species has accustomed to living. Monkeys live in trees and a tail provides much needed support to thrive in that environment. Humans do not live in trees nor do they swing for place to place. The idea is that humans once had tails as well and the need for them faded away over time so eventually the tails themselves faded away.
c. Evidence does point to a common ancestor between monkeys and humans. To be more exact, there is a common ancestor between apes and monkeys, and there is a common ancestor between humans and chimpanzees that classify humans as apes to begin with. The ancestor is not exactly named but is said to have lived roughly 25 million years ago, but there has been no fossil evidence to prove that it had a tail. We know it had a tail because of the evolutionary timeline of each species. If you trace back far enough one can predict that the ancestor of each species had a tail at roughly the same time period.
d.
Analogous
a. A penguin's wing and a dolphin's flipper are analogous traits. A penguin's wing is smooth and sleek and cuts through water very well. A dolphin's flipper is also smooth and sleek very similar in texture and structure to a penguins wing. It also helps the dolphin easily cut through water.
b.The penguin's wing sits at the side of the body. It's structure resembles that of a wing except in most birds the wing enables them to fly. A penguin's wing does not. The reason for this is that in Antarctica a penguin does not need to fly as much as it needs to swim. The main source of food in the environment is fish, so penguins needed to adapt and become great swimmers rather than flyers and a sleek wing enables them to do that. Although the penguin is a species of bird, it acquired a trait similar to a dolphin due to the fact that it needed to perform similar functions in order to catch its food. In dolphins the flipper helps cut through water and enables the dolphin to swim at high speeds to catch its prey. This is the same function the wing on a penguin serves. There it is determined that the trait is not a from a common ancestor between the two, but was developed over time as an example of evolution within two different species to adapt to their environment.
c.The common ancestor between the two species was some type of reptile that lived about 360 million years ago. It was the same common ancestor between birds and mammals. The reptile was said to have been some type of four footed fish that had lungs but primarily relied on under water breathing. We do not know specifically if it possessed the trait because there is no fossil evidence yet however it was assumed to live primarily underwater therefore we can assume it did have some type of sleek fin to help maneuver effectively underwater.
d.
I used the penguin and dolphin fins as my analogous comparison as well. I could not find nor think of any common ancestor but then again if we base our knowledge that dinosaurs were the first creatures, or reptiles then it is possible there was a common ancestor.
ReplyDeleteYou kind of jump right into the discussion of the trait comparisons, but the opening section in both the homologous and analogous areas asked for a description of your species, not just identification of the species or the traits. This would help your reader understand the environment and behavior of the species to better understand why their traits evolved the way they did. Needed to be expanded.
ReplyDeleteHomology: Good description of the monkey's tail, though understand that only New World monkeys use their tail in a pre-hensile fashion. Old World monkeys do not.
"A human's tailbone serves no real purpose."
Actually, it serves as a muscle attachment for many of the perineal muscles and serve important excretory and reproductive functions.
"It is just the single bone. "
No, the coxxyx (tailbone) is made up of five little bones, though that can vary. Perhaps you are thinking of the sacrum?
The move from the trees to the ground may well be one of the factors that led to the loss of the tail in not just humans but apes in general. We actually start to see this reduction in Old World Monkeys. Good attempt to explain this. It is still an open discussion among anthropologists.
"The ancestor is not exactly named but is said to have lived roughly 25 million years ago, but there has been no fossil evidence to prove that it had a tail."
Sure there is!
https://3c1703fe8d.site.internapcdn.net/newman/gfx/news/hires/2009/earlyskeleto.jpg
And: https://i.cbc.ca/1.1568382.1379050603!/httpImage/image.jpg_gen/derivatives/original_780/sm-250-archicebus-fossil-press-release-media1.jpg
And because we know the common ancestor (via fossil evidence) possessed the tail, we know that the two traits in humans and monkeys are genetically related, in spite of their differences, and are therefore homologous.
Analogy: Very good description (second section) of the similar environmental pressures that produced the similar structure and function in these "fins".
"The reptile was said to have been some type of four footed fish that had lungs but primarily relied on under water breathing."
No. A reptile is not a fish. But you are correct that the common ancestor between the penguin and the dolphin was an archaic reptile. But how do we use that to confirm that these traits are indeed analogous?
"We do not know specifically if it possessed the trait because there is no fossil evidence yet"
The question here is about fins. Some aquatic reptiles had fins (and we do have fossil evidence of this), but the ones that gave rise to mammals did not (of which we also have fossil evidence). That his key here.
Let's walk through how the logic works here:
Dolphins are mammals, who arose from archaic reptiles. Penguins are birds, who also arose from an archaic reptiles, so the common ancestor was an archaic reptile. We know from the fossil record that the generalized limb structure of reptiles did NOT include fins, but we also know that the fin structure in both of these species arose long after this split with the common ancestor. Dolphin fins arose after they split from terrestrial mammals and penguin fins are derived bird wings. That is what we need to know to confirm that both these traits arose independently from that common ancestor.
Good images.
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