Homologous Traits
The wrist bone of the human being is homologous with the structures of many other animals such as the dolphin.
The dolphin and human are both mammals and have the same genome.
They both share humerus bone fragments, carpals, ulna.
Although, dolphins live in water and humans do not they share many of the same characteristics
that their ancestors have passed down.
The common ancestor appears to be a reptile.
Analogous
Two flying species that one would consider the same are in fact analogous.
The butterfly and the bird. The butterfly is an insect (invertebrate) while birds are vertebras and are warm blooded.
both have wings, both can fly.
The butterfly's wing has a fixed shape and an ecto-skeleton and look more like a leaf.
whereas the bird has forelimbs composed of three limb bones..the humerus, ulna and radius.
Although they share the same similarities, they did not evolve from the same ancestor because we know that the bird's ancestor is a reptile, I am not sure where the butterfly evolved from.
Hello! I also like you found it interesting that so many different mammals shared the same genome with the humerus, carpals, and ulna. Although I am not positive that the reptile is the common ancestor for humans. Due to the environments of both the butterfly and bird, it is amazing to see that the trait of having wings comes separately yet serves the same purpose. The butterfly evolved from being a caterpillar and before that a larva. But I also cant find what that ancestor would be.
ReplyDeleteHI! If you put a butterfly, bird, and lets say a human being and asked me to pick the two that were similar I would say that a butterfly and a bird were more alike but that isn't true. A bird and a human being have more in common because their bone structure by the bird's wings and human being's arm. It is extremely interesting to discover all these different homologous and analogous traits in all these different species.
ReplyDeleteThe 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.
ReplyDeleteRemember that homologous traits are inherited from a common ancestor but exhibit differences due to environmental differences producing divergent evolution. You describe similarities and then mention that their are differences, but you don't discuss those differences, which was the intended focus here.
You initially said you were focusing on the wrist bone. That's fine. It's a valid comparison. But what are the structural differences between the wrist of the human and the "wrist" of the dolphin? And how does that translate into functional differences? And can you then connect those functional differences with the differences in their environment? For homologous traits, similarities are not surprising, because these traits are related genetically. It is the differences that need to be explained.
"The common ancestor appears to be a reptile."
Both the human and the dolphin are mammals. Why do we need to go back to reptiles to find a common ancestor? And how do we use this information to confirm homology?
Okay on your description of your analogous traits, but the focus here was the structural, functional and environmental similarities that produced these traits. This needed to be more fully explained, particularly the issue of the environmental pressures that drove this evolutionary process.
" they did not evolve from the same ancestor because we know that the bird's ancestor is a reptile"
That doesn't mean they don't share a common ancestor. As explained in the guidelines, ALL organisms share a common ancestor if you go back far enough.
It is difficult to guess at what the common ancestor of the bird and butterfly looked like some 100's of millions of years ago... it may have possessed wings or it may not have, but fortunately, we don't need to know that to confirm that these traits are analogous. While it is possible that the butterfly inherited its wings from that common ancestor, what about the bird? We know quite a bit about bird and bird-wing evolution. Birds evolved wings as they split from reptiles, and this occurred long, long after the split with that common ancestor with the butterfly. This means bird wing evolution occurred independently from that common ancestor with the butterfly. That is sufficient to confirm that these are not the product of common descent and are indeed analogous.
Good images.