Homologous:
A. A homologous trait that both human beings (homo sapiens) and bats (chiroptera) are located in the forearms of both species. They structurally differ a bit and have different purposes but they share common underlying anatomy and traits.
B. Although the outer appearance of a human forearm and a bat's wing differ greatly, they both contain the same bones: humerus, radius, ulna, carpals, metacarpals, and phalanges. However, the bones of a bat are much smaller and are more delicate. This is due to the fact that the overall forearm/wing of the bat must be lighter in order for the bat to fly in the air with ease. All vertebrate limbs are put together in the same fashion, thus these specific species are homologous for forearm traits.
C. The common ancestor of this trait would be tetrapods. Tetrapods were the first four-limbed vertebrates and their descendants include the living and extinct amphibians, reptiles, mammals and birds.
Analogous:
A. The analogous trait that I will be explaining are fins, specifically the fins of a penguin (Spheniscidae) and the fins of a general type of fish. Although these animals differ in size, appearance, and ancestoral origin, they share a similar aspect: their fins and the purpose behind them.
B. Although the outer appearance of a penguin and a normal-sized fish differ greatly, they both obtain fins on the exterior of their body which serve similar purposes. For both a penguin and a fish, their fins are necessary to help navigate themselves in their aquatic habitats.
C. Since a penguin is a bird and the other creature is a fish, it is underlined that the fin evolved in these extremely different species because it was a necessary functional feature to survive in their environment rather than being inherited from a common ancestor. These two species do not likely have a common ancestor because they come from two completely different classifications.
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Good explanation for the structure of the bat forelimb. What is the human forelimb designed for? You left out half of the explanation.
ReplyDeleteDo you need to go all the way back to the early tetrapods (early amphibians) to find the common ancestor of these two organism? Both are mammals, so could we use the common mammalian ancestor instead? You have the right idea, but if we are looking for the common origin, it is much more recent.
Good description on your analogous traits.
Remember that all organisms have a common ancestor if you go back far enough, so we can't use that logic to confirm that these are analogous. In this case, the common ancestor would be early fish, giving rise to not only modern fish but also amphibians, then reptiles, then birds and mammals. And it is likely that that early fish had fins and passed them onto modern fish, correct? So are these homologs? I order to answer that, we need to know how wings arise in birds (since the fins of penguins are adapted wings). We do know quite a bit about bird evolution, namely that wings of a bird arose after they split off from reptiles, long after that common ancestor between birds and fish. That is what we need to know in order to confirm that fins arose independently in at least one of these species with that common ancestor.
Good images.
The homologous section of your work is super interesting. I had no idea humans had bones in are forearm similar to that of a bats. I'm kind of jelly bats have the ability to fly while us humans are stuck on the ground.
ReplyDeleteIn regards to your analogous post. I actually wrote about the same topic. I also made the same mistake thinking penguins and fish did not have a common ancestor. Overall we had the same idea about penguins and fishes fins. How there fins are similar and are necessary for their survival.
Great Post! I really enjoyed learning from it.
Your post really caught my eye because I also did the same thing for analogous traits. I did the penguin fin and the fish fin. I thought the homologous trait you chose for the human arm and the bat wing was really interesting. It's so crazy to think that humans and bats share a common ancestor. Your post is really informative and filled with interesting facts! Great post, and I also really liked the pictures.
ReplyDeleteI really enjoyed your post! It was nice to see some examples of a fully completed post. I ran out of time on mine to get the whole ancestry. For the analogy part I was having such a hard time trying to figure out how my two species could be related and by what animal. By the end of this assignment my head hurt so bad. Now I know they don't and won't always have a common ancestor. Also, looking at a penguins "wings" as "fins" is very clever! That completely makes sense and something I completely over looked. I was only able to see the penguin as a bird with non fully functional wings. Again good job!
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