Homologous Species
The two species that possesive the homologous traits are cats and whales. Cats have four legs with a similar bone structure to humans as well as the similar bone structure to the fin of the marine animal, whale. The structure of the fin and leg are the same, but as you can see in the image above, the whale has a wider humerus, ulna, radius, and carpals, and has longer phalanges. Although their structures are the same, their functions are different. Cats use their hands in order to be mobile on land and their paws allow “act as shock absorbers for jump-landings”, while whales use their fins to stabilize themselves so that they do not roll around in the water ("Structure and Function of the Claw and Foot Pad in Cats" 2015). The common ancestor for both whales and cats, along with humans and bats, is the placental mammals, which “weighed between 6 and 245 grams,” and lived about “100 million years ago,” right after the dinosaurs became extinct (Wong "Meet the Last Common Ancestor of Bats, Whales, Sloths and Humans"). These two species may seem very diverse today, but millions of years ago, they both evolved from the same small common ancestor.
Works Cited
Gill, Victoria. "What can killer whales teach us about the menopause?" BBC News. BBC, 11
Aug. 2016. Web.
PetPlace.com. "Structure and Function of the Claw and Foot Pad in Cats." Pet Place. N.p., 03
Aug. 2015. Web.
Wong, Kate. "Meet the Last Common Ancestor of Bats, Whales, Sloths and Humans." Scientific
American Blog Network. N.p., n.d. Web.
"49 Genius Tabby Cat Names You’ll Love." Find Cat Names. N.p., 06 Mar. 2017. Web.
I liked your post! I learned a lot, I didn't know what their common ancestor would look like so great picture.
ReplyDeleteBut I think you should have described the species characteristics since they are very different from each other.
- Adriana Chaparro
You needed to include both sections in one post. I almost docked you points because you were missing half of your post until I took a second look and found the other half in a separate post.
ReplyDeleteDON'T delete either post or you could lose student comments. From now on, assignments should include just one post, not multiple.
I'll cover your homologous section first then take a look at your analogous section and post the critique here as well. I won't post a comment on your analogous section.
Homology:
The opening section in both the homologous and analogous areas asked for a description of your species, not just identification. 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.
Good description of structure and good description of function, but can you tie them together? How does the structure of the whale fin help with their function? How can you explain the cat limb structure in terms of its function?
Correct, both the cat and the whale arose from a common archaic mammalian ancestor.. but how does that confirm these are homologs?
We know from fossil evidence that the common mammalian ancestor possessed the primitive structure and passed that trait onto these two descendants with variation arising due to different environments and functions. That is what we need to know to confirm that these are homologous traits.
Good images.
Analogy:
Missing the discussion "on the similarities in structure and function of the traits" in question here. Yes they are both wings, but what similarities do they possess that help with their function?
"Bats and birds do not have a common ancestor from their wings, but they do have a common ancestor from their forelimbs."
Yes! Can you figure out the general common ancestor for their limbs? And how do we use this information to confirm that these wings are analogs, not shared genetic traits?
Bats are mammals and birds are, well, birds, and both arose from archaic reptiles. From fossil evidence, we know that early reptiles also possessed this primitive limb structure but NOT the wing structure. We also know from fossil evidence that birds evolved their wing structure during or after the process of splitting off from reptiles. We also know that bats arose from non-winged mammals, meaning their wings are derived traits, evolved independently from that common ancestor with birds. That's what we need to know to confirm an analogous relationship between these two traits with no common genetic origin for the winged trait, even though there is a common genetic origin for the ancestral limb structure itself.
Good images.
I'll connect this comment to the one on your other post. Again, I like this work cited. I also did whales, but I compared them to dogs. Your response is much more cohesive than mine, so that really helps me as a student understand how I could've done better.
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