Two species that propose an homologous trait are humans and canines. Humans and canines serve a similar bone structure when it comes to arms and dog limbs but they serve a different function. Both have a humerus, a radius, a ulna, carpals, metacarpals, and phalanges, but are used for different activities. Such as, humans walking on two feet and not four, and humans using their hands and arms for everyday activities such as driving, and dogs using their front limbs for activities such as jumping or climbing. It is hard to decipher a common ancestor between a dog and a humans. A dogs common ancestor would be a wolf whereas a humans common ancestor would be the chimpanzee, which is very different from a wolf but also shares the bone structure.
Two species that identify with an analogous trait are flippers of a penguin and the flippers of a humpback whale. While the flippers of a humpback whale are much larger than the flippers of a penguin they serve a similar structure and a similar function, to maneuver through water. The humpbacks whales flipper have non-smooth leading edges but yet they help this large mammal move smoothly through the water. The penguin's flipper consists more of massive but short and flat bones and is scaled with feathers, but with this flipper, like a humpback whale, penguins cannot fly. These flippers, like whales, help the penguin maneuver through the water even though they are much smaller. Whales and penguins use their flipper for hunting as well, penguins use it to swim quick and force to catch prey, whereas humpback whales will swim in circles to trap prey in the middle and later eat them. The common ancestor of a humpback whale would more or less be a hippopotamus. Hippos evolved form a group called anthracotheres fifteen million years ago, whereas the first whale evolved fifty million years ago. The common ancestor of the penguin is Albatrosses which are seabirds. Moreover, Penguins and Humpback whales possess a similar flipper that serves a similar purpose in their different worlds.
With your homologous example I think you did a really good job. I didn't know we can use humans but I really like that you did. It was very straight forward and done well. Same for your analogous example but I think you mixed up the two a little because analogous traits are like the same experience not just having a flipper. But good job overall.
ReplyDeleteHi,
ReplyDeleteI enjoyed your post because it cut to the point and all the information was clear. I think your comparison of a whale and pengiun flipper was really cool! I wouldn't have thought about comparing those two species. If I recall correctly we are supposed to have a picture of the animals for both homolgous and analogous (not sure if the bone photo) counts, but just letting you know in case it could save you some points! Once again, I found your post really unique and well written.
The guidelines break up the prospective post into different prompts. Please format your post accordingly with different paragraphs for each prompt so that I can locate where you address each question more easily.
ReplyDeleteThe opening prompt for both sections specifically ask for descriptions, not just identifications, of your two species. Expand and provide your readers with a better foundation of understanding for these comparisons.
Good description of the difference in function, but can you connect that with the differences in structure? Why do their structures differ? This needed to be explained.
The term *common ancestor* is asking for the one ancestor both species share. You are identifying different ancestors for both, but you needed the one common ancestor that both share. For example: Both humans and dogs are mammals, so we know that the common ancestor would be an archaic mammal. We also know from the fossil record that early mammals possessed that generalized mammalian limb structure and passed that onto these two descendant species, with changes concurring over time due to differences in the environments and functions. That is what we need to know to confirm common genetic origin and confirm homology.
Analogy:
Good description of the similarities in structure in terms of their similar functions. Well done on this.
Same problem as above with ancestry. Whales 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.
Homology:
Hi,
ReplyDeleteI really enjoyed your post. I didn't realize penguin fins and whale fins were so different. I also liked how you compared canines to humans. I thought about comparing dogs to cats but I like your comparison more. The picture explaining the bones of humans and canines helped a lot too. Good job!