- A. Many whale and bat species share common evolutionary ancestors,(the two are not linked) and have homologous traits. Homologous traits are traits that are similar to one another due to shared ancestry. As species adapt to their environments and evolve over time, these traits may change in appearance and in function, but ultimately they still share the structure, genetics, or embryonic structure of their common ancestor.
- B. Whales do, of course, share a common ancestor but this common ancestor is not the reason that whales have their aquatic adaptations. The ancestors of whales first evolved into a terrestrial life, then evolved back into the water, much later in life. And as for the bat species the trait was used primary for flight the differences between these two species traits is the analogous structures traits similar in origin but dont have a common ancestor.
C. Welling carnivore called Pakicetus was the common ancestor of the whale the ear bones and teeth of Pakicetus are similar to those of modern whales and as for the bats they are closely related to lemur due to their arms were great for grappling just like bats hanging upside down.
- The human and the ape both species have upper and lower limbs and are made up of similar bones and muscles the general function is the same even if the specifics vary slightly. humans have shorter arms than legs while as apes have longer arms than legs.
- Apes do more walking than climbing but still have the same structure. both ape and man have similar bone structure as well as muscle for example Humans can walk and run longer distances than apes whereas apes can climb better without struggle.
C. Australopithecus afarensis is the common ancestor of both ape and manThe shoulder of Australopithecus afarensis was more like an African ape than a human, and closer to human’s than to an ape’s.This positioning is consistent with evidence for increasingly sophisticated tool use in Australopithecus. C.Australopithecus
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ReplyDeleteI need to makes a couple of corrections on misconceptions from your first sentence:
"Many whale and bat species share common evolutionary ancestors,(the two are not linked) and have homologous traits."
Actually, ALL whales and bats share a common evolutionary ancestor since they are both mammals. But then you go onto say that they are "not linked" which argues the exact opposite. As explained in the guidelines, all organisms share a common ancestor if you go back far enough. The question, with regard to homologous traits, is whether or not that ancestor possessed the ancestral trait in question and passed it onto the two extant species.
"Whales do, of course, share a common ancestor but this common ancestor is not the reason that whales have their aquatic adaptations. "
Yes, all whales share a common ancestor, but what we need to do here is discuss the common ancestor between whales AND bats, not just the common ancestor of whales OR bats.
You don't identify the trait you are comparing for your homologous trait. The most common for a whale/bat pairing would be the forelimb. Is that what you are referring to? This was a key part of the prompts, asking you to explain how the function of these traits relates to their structure, and how this explains why they are structurally different even if they share common ancestry.
Regarding your section on ancestry, again, we are looking for one common ancestor for both whale and bats. We don't need to get specific. Since both whales and bats are mammals, we can confirm that the common ancestor was an archaic mammal. We know from the fossil evidence that early mammals possessed the ancestral form of the forelimb (if that is the trait you are comparing), confirming that the similarities in these traits are due to common descent while the differences are due to divergent evolution.
For your section on analogy, remember that analogous traits must (a) not arise from common descent, i.e., the common ancestor did NOT possess the ancestral form of the trait and (b) the traits share similarities due to similar environmental pressures, i.e. convergent evolution. Does your example of human and ape limbs satisfy these requirements?
In short, no. Humans ARE apes, so that is the first problem here. Second, with regard to the issue of ancestry, humans and apes go back about 6 millions year ago to the common ancestor, much farther back than A. afarensis, who is a human ancestor, but not a general ape ancestor.
Third, did the common ancestor between humans and non-human apes possess this archaic primate limb trait? Yes, they did, which means that that ancestral trait was passed on to all descendants, human and non-human. That means the requirement of non-common descent isn't satisfied. So the reason human and non-human ape limbs are similar is due to common ancestry, not due to similar environmental pressures.
The structures you discuss here are the product of *divergent* evolution (i.e., they are homologous traits) instead of *convergent* evolution (which produces analogous traits. These are key concepts. If you need additional clarification, please post questions here or email me.