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Sometimes very distantly related species live in the same or similar environments for a long time. The adaptations that let one species survive are the same adaptations that make the other species well suited to its environment - so they start to resemble each other more and more, even though they are not closely related.
but doesnt the fact that the lesser panda is raccoonlike show differences in anatomy?
But what if the Lesser Panda was closely related to bears - but relatively recently moved into a new niche in the ecosystem? Then a totally different set of traits would make the Lesser Panda more adapted for its new environment, it would evolve quickly and soon look quite different than the bears, even though they were closely related.
I'm still a bit confused. I guess DNA sequencing is the ultimate test for relatedness but doenst comparing anatomy also show relation? e.g. homologous traits?
In real life comparative anatomy usually gives a pretty good indication. If I were you I would forget the Pandas example and concentrate on the theory. Let's say you have two organisms which diverged a long, long time ago. So long ago that for the purposes of discussion, they are unrelated. If these two different species live together in the same environment for a long time, they will face the same selective pressures and will develop similar responses to it. So much so that they will come to look very like each other, even though they are distantly related. Now imagine the opposite case: two species which are closely related, but for whatever reason suddenly live in very different environments. They will face very different selective pressures; different features will make them well adapted for their environments, so they will end up looking quite different even though they are still closely related.
ok I think I get the theory. so fitting it back to the panda problem, even though the two pandas may have developed similar anatomy due to similar environments, they are actually very distantly related as compared to the giant panda/bear which are more closely related but in different environments.
and the only way to tell is through DNA comparisons
Yes, I think that is correct with respect to the Pandas.