1a. Briefly describe the two different species that possess
the homologus trait.
Humans
and Whales
1b. This image shows
how evolution has shaped hand bones to perform different functions. Human hands
have evolved to grab and hold things, while whale "hands" have
evolved into flippers to help with swimming.
1c. Below you will
find the image of a tree-climbing, insect-eating beast that weighed between 6
and 245 grams and gave birth to one hairless baby at a time. According to a new study, this is the common
ancestor of all placental mammals. If we
look at the conceptual image we can see the same hand like structure of our
human and whale. I would not make
assumptions (of course further research is necessary) however, I would wager
the “hand” structure would be similar to the human and whale “hand” structure
that we are looking at now.
2a. Briefly describe the two different species that possess
the analogous trait.
The
turtle and the snail.
2b. The
similar analogous trait that both of these species share is they both have
their “shell”; the hard exterior casing on the top of each creature for
protection. Both species can shrink inside of their shell which helps protect
them from any outside threats, however,
the snail’s shell is secreted by specialized glands in the mantle whereas the
turtle shell is modified skin.
2c. Actually in 2008 a team of scientists had
reported the discovery of the oldest aquatic turtle, dating back 164 million
years that only had a half shell which only covered it’s belly leaving it’s
back unprotected. This turtle species
that swam in China's coastal waters 220 million years ago is the oldest turtle
known to date.
Thomas, I think your post is well crafted, with great background information on all species you chose to analyze. I especially think the information about the snail and turtle show that you have a good grasp of the subject, or, at the very least, you are an efficient researcher. The image of the common ancestor of humans and whales is a nice addition to the post.
ReplyDeleteGood choice of homologous trait and I like your explanation of the difference in structure and function. The images really helped clarify your point.
ReplyDeleteOn the right track with ancestry. Yes, that is a possible candidate as the mammalian "Eve", but the more important point to take from this is that since both organisms are mammals, they share a common mammalian ancestor who possessed this archaic mammalian limb. Yes, it would have be more generalized and not necessarily resemble the modern limbs, but that is itself part of the definition of homologs. Common descent with structural differences arising from functional/environmental differences.
Excellent example of your analogous trait along with a good explanation of structural similarities arising from similar functional needs.
Very good evidence for ancestry. Yes, turtles evolved this trait well after the split with the common ancestor with the snail. We know less about snails but this is likely the case with that species as well. This is the information we need to confirm that these traits did not arise with that common ancestor through genetic inheritance but through independent evolutionary events.
Good post.