1) a. The two species that posses the homologous trait would be humans and whales. The trait they are similar in is their bones structures in which the front fins of the whale are similar to the bones in the arm of a human.
b. Trait from both humans and whales are their bone structures. The fin for the whale and the arm for a human. Both have slight differences and functions as well. The bone in the fin for the whale are much larger in scale and have for length to them only because the whale itself is such a large mammal. The bones in the arm of a human are named off like the ulnar and radius, also small compared to the whale. The functions of both species are different of course because humans are land creatures and whales are sea creatures. Whales use their fins to be able to swim through the ocean while humans use their arms to lift things, eat, defend themselves, etc. Their traits are different because of their use for them and what their purposes are for.
c. A common ancestor for both the whale and humans would have to be a mammal itself since both humans and whales are mammals themselves, the ancestor itself would have started off as a water creature since that was the evolution that humans came from millions of years ago and whales have some genetic trait with that since being a mammal and a water creature give them the similarity.
d.
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| Whale |
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| Human |
2) a. The two species that share the analogous trait are dolphins and herrings. They both live in water, but the dolphin is a mammal and the herring is a bony fish.
b. Both the dolphin and herring both have their similar traits by having fins to swim around, and also gills to be able to breath under water. They both are primary predators and hunt smaller things for them to eat using their fins to swim around the water and to get away from other dangers as well. They are mostly similar because of what environment they are in which is the ocean and need to stay on alert on things also being able to catch their food when they need to.
c. The common ancestor for the dolphin and herring would be some kind of a fish since herrings themselves are fish and have been around in the water for millions of years, dolphins share the trait since they are also water creatures as well and give an environmental trait itslef.
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| Dolphin |
Good choice of trait for your homologs and good descriptions. You are correct to emphasize the skeletal similarities and the functional differences that produced the physical variation.
ReplyDeleteChimpanzees are modern animals, like humans and whales. They didn't exist when the split occurred between whales and humans and could not have been the ancestor of these descendent species.
We know that both humans and whales are mammals, therefore the ancestor was a mammal, and all mammals share this common forelimb skeletal structure, albeit with variations. That is what we need to know to confirm that these are homologous traits: Origin from a common ancestor with variation produced by different environmental stresses.
The fins of dolphins and herrings are analogs. You focus a lot on their differences, but I needed to hear more about how they are similar even, and why, even though these traits arose independently. How does the structure of the fin help given their environment?
Herring are fish and fish have been around for hundreds of billions of years. There was no intermediary land ancestor of the herring. They have always been water organisms. Dolphins did arise from land animals, but if you look for the common ancestor of these two organisms you have to all the way back to the age of the fishes, which did have fins. But dolphins developed fins on their own, independently after they split off from land mammals, which is why these are indeed analogs.
Make sure you get a chance to review the issue of ancestry and how that relates to homologs and analogs.
Hey Corey!
ReplyDeleteI really enjoyed your species that either have a homologous or analogous trait. I never thought of a whale fin and a human arm to be homologous, but your description actually makes sense to me. Very interesting. I also enjoyed your analogous trait description with the dolphin and herring. Very cool to think about how dolphins, a mammal, became a water animal with fins and all! good job!
-Danni Thompson