Monday, January 14, 2013

Analogy & Homology


 The human and the horse both have similar bone arrangements. The human arm is designed in a way that allows us to carry and use tools to help us with our survival. Whereas the horse’s front leg is designed to run, jump and support their weight. Due the fact that the horse leg and the human arm have the same bones but are different in size and strength the bones are extremely similar and show that somewhere back during the beginning of evolution all mammals came from the same common ancestor.

The seal and the lizard both have front limbs that are similar, but the both have different functions. A seal’s front force flipper is what allows the seal to propel through the water as well as walk on land. Whereas the lizard use their legs to climb, run, and jump. The details in the arrangement is what allows these animals to do this. This may also mean that they may have a common ancestor but somewhere down the line the evolution of their front legs skewed into different adaptations.  


7 comments:

  1. I thought you chose fascinating species to compare in both categories! Doesn't it amaze you how at a glance you would never suspect two things to be related? It is so interesting to see how all types of organisms and living things can compare and contrast, it really shows the beauty of life. When comparing the homologous traits of the horse legs and arm legs I actually pictured the horse in my head and saw how in structure they were very similar, especially with the bend in the knee. In my research and reading I also came across the fact that all mammals have come from a common ancestor and it still amazes me to think how much time has gone by and how amazing it is that we can all trace back our roots so far. In regards to your analogous trait of the lizard and seal if you could take your best guess what would you think the common ancestor between the two would be? I also faced difficulty on my analogous traits, the bird wings and butterfly wings, in finding and even thinking about where the common ancestor back in time would lie. Very interesting blog post! Hope you learned and enjoyed it as much as I did.. so crazy!

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    1. Shira,
      Thank you for your feed back on the homologous traits. It took me a little while to find something but I soon realized that mammals with the same basic one structure and design originate from some type of common ancestor. Also i was a little skeptical about the analogous traits and was trying to understand it more. I even googled it to try to make more sense of it but i had a hard time understanding the concept. Thank you for the example though the Bird wing and butterfly wing makes a lot more sense from what i understand.
      THank you for your feed back :)

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  2. The basics are here, but one of the key words in the guidelines is the word "describe". More thorough descriptions throughout the post were needed.

    The homologous trait is accurate. Can you offer descriptions on the two organisms? Also, you are correct in your line of thinking behind the origins of the different structures, but it could have been taken further. What about the difference in the distal appendages, namely the hoof and the hand? Fine on the ancestor.

    The seal appendage and the lizard limb are actually homologous traits. Both mammals and lizards can trace back their origins to a common ancestor, who was also a lizard with that limb structure close to what we see in lizards today. The seal limb has changed over time to adapt to it's aquatic environment, but it is still homologous because it shares a common genetic ancestry with the lizard. Make sure you review this concept so that you understand what makes analogous traits analogous.

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    1. Professor,
      I realized that I forgot to talk about the hand and the hoof which is a huge part of the evolution of organisms because the human hand and horse hoof are structured completely different.
      I was a little hesitant about the analogous structure. I found it a little hard to grasp but with the example Shira gave me I understand it a little more than I did before. Thank you for your feed back and I will improve in what I lack on with my blog post. :)
      Thank you so much
      Justin

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    2. Thank you for replying back.

      If you want to get more information on this in kind of a fun learning setting, give this a try (you will have to copy/paste the link):

      http://evolution.berkeley.edu/evolibrary/article/similarity_hs_01

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  4. Good job Justin, i fine the comparison with the human and the horse arm very interesting. It's amazing how when we research any species we fine similarities to humans in many ways. Prior to this course i would never think the horse and the human had similar arms. I also found your comparison of the human hand and the flipper very interesting. It amazing how these two compare and the different ways they use their trait. Again, good job.

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