Homologous
The different species that posses the Homologous traits in the picture are a humans arm, a cats arm, a whales fin and a bats wing. The structures are all different but share quite a few things. These four pictures show different areas of joints and limbs that all they all share in the structure. The different shadings of colors is where they all bend in the same spot in each of the species. Even though animals and humans don't have the same amount of limbs, bones, or joints they all have the same locations of each one. These all animals and human shown in the picture surely ancestor by evolving from another animal many years ago.
Analogous
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Unlike a snail and a turtle these structures are know as a Analogous. The two structures both are different, one has a body full skin and the other is full of bones. That is why this is Analogous, the two animals are alike by being completely slow animals and having a hard shell to protect them from whatever comes there way, but the snail has no bones whatsoever and a turtle does have bones shown in the structure. Although it may seem that these two animals could have ancestor together because of there hard shell , they do not ancestor. They are evolved separately.
Very good description and explanation of your homologous traits. More support was needed for your discussion of ancestry, however. All of these organisms are mammals and inherited the ancestral limb structure from the common mammalian ancestor. So the similarities are inherited but the differences are evolved, which is the opposite of analogs (similarities are evolved and differences are inherited).
ReplyDeleteLove the snail and turtle comparison! These two organisms are distantly related but that distance doesn't automatically mean these traits are analogous. We do know that the turtle shell is a unique, derived trait of turtles and tortoises, not inherited from the distant reptilian ancestors, since not all reptiles have a homologous structure for the shell. That means the turtle shell arose independently from the common ancestor with the snail and these traits are analogous.
Good images.