1)
Homologous traits
A) Humans and monkeys have a lot of the same
traits, but the one that I am talking about is the tailbone. Even though humans
don’t have tails, we still have the tailbone.B. Humans don’t have a tail physically showing, but we still have the bone and it is in the same structure as the monkey has. The tailbone in a human is the last part of where the tail would be. The only difference between us is that we have the bone for it, but don’t actually have the tail coming out, the monkeys do.
C.
Primates are both of their ancestors, primates
also had a tail bone and a tail.
2)
Analogous traits
A.
Penguins and dolphins both have fins. Having
fins doesn’t make them related in some way.
B.
They both look exactly the same just on
different body parts for both animals. The penguin has two fins on the side of
them used as wings and the dolphin has one their back used to swim throughout
the water.
C.
The penguin’s ancestors are birds and the
dolphin’s ancestors are mammals. The birds of course had fins because penguins
ended up with them, but mammals did not have any fins in the past ancestors
they had.
hey rouba, i think your comparison of a human and monkey was a good idea. but is there a specific animal they evolved from? i thought the comparison between the two fins was good. i might have chosen another mammal to compare the dolphin to though. overall good work.
ReplyDeleteNo argument that the tail and tailbone are homologous traits and you are fine on ancestry, but part of demonstrating homologous status is to show that these traits have assumed different functions from each other. So what is the function of the tale in monkeys and the tail bone in humans?
ReplyDeleteTo clarify your analogous traits, the structures on the penguin ARE wings. :-) They are birds, after all, but their wings have developed into derived fin-like structures that help them move in the water like the fins of a dolphin. That is the structural relationship we are looking for to help us identify analogs.
The question on ancestry is about a common ancestor, and penguins and dolphins do share a common reptilian ancestor (ancestor of both mammals and reptiles). But the key point is whether these fin structures evolved independently from that common ancestor. Fortunately, we know that penguins derived their "fins" from bird wings after their split from reptiles and dolphins derived their fins from their ancestral mammalian limbs, also after their split from reptiles, evidence that both traits arose independently through convergent evolution, not from common descent.