Thursday, November 4, 2010

Homologous/Analogous

1.a. Two different species that possess a homologous trait are humans and whales. The structure they have in common are the human hand and the whale flipper.  They are similiar in bone structure however whales use their flippers for swimming and humans use their hands for holding objects and other things like that.

b. The function of whale flippers focus on movement in the water. This trait is only found in aquatic mammals not on land. Human hands can be used for a variety of things such as throwing, pushing, grasping and etc. Human hands are not generally associated with movement as a means of transportation. Its interesting because the whale flipper or fin is extremely similar to the structure of the human hand but still has a different function. Whale flippers have a thumb and 4 other finger bones just like humans. Although the finger bones of whales are very wide and compact unlike the human hand. Also it contains less bones. The shared trait between the two species is different because they have evolved to be used for different purposes.

c. Their common ancestor was a land living mammal and we can confirm that by comparing fossils to the present day species.


2. a.  Two species that possess an analogous trait are birds and butterflies. Birds and butterflies both use wings to navigate but they are completely different in structure.
b. Although they have the common trait of wings, the butterflies’ wings are composed of tiny bones, completely different from the composition of a bird’s. Both species have responded to the environment by adapting and growing wings. They do not share a common ancestor but instead share a common adaptation to the environment.
c. If you go back far enough in time when they had a common ancestor, the common ancestor would probably not have wings because it would have adapted to a very different environment.

2 comments:

  1. Good effort I must admit but I beg to differ. Unless you have come across less developed tribes and primitive people across the globe you just have no idea what simple hands can do to transport nearly impossibe loads. I am also impressed with the example of whales that you used. I was facsinated by the experience that I obtained when I visited Sea World for the first time. That whole Shamu adventure still sends chills down my spine up to this day.

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