1. For your homologus traits provide the following
information (25 pts):
a. Briefly describe the two different species that possess
the homologus trait. (5 pts)
Examples of 2 species that have homologous traits are a
lizard and a snake.
b. Describe the homologus trait of each species, focusing on
the differences in structure and function of the trait. Why do these homologus
traits exhibit differences between the two species? Make sure your explanation
is clear and complete. (10 pts)
The structures that are similar on these animals, is the
tails. They both are used as a moving mechanism, but they have different levels
of manipulation on moving. For example, the lizards still has legs, so it doesn’t
rely upon the tail as much as a snake does.
c. Who was (generally, not specifically) the common ancestor
of these two species and how do you know that ancestor possessed this homologus
trait? (5 pts)
The common ancestor had to be a lizard of some kind, but
along the way the change occurred to differentiate a snake and a lizard apart.
d. Provide an image of each species in this comparison. (5
pts)
a. Briefly describe the two different species that possess
the analogous trait. (5 pts)
Examples of an analogous trait would be a black bear and a
polar bear.
b. Describe the analogous trait of each species, focusing on
the similarities in structure and function of the trait. Clearly explain why
these analogous traits exhibit similarities between the two species. (10 pts)
Black bears have fur that allows them to hunt, migrate, and
protect themselves from harm of environmental and natural factors. Polar bears
have fur that protects them from the cold and harsh environment of the arctic.
It also provides a great cover against the snow for predators.
c. All pairs of organisms share some common ancestor if you
go back far enough in time. Could the common ancestor of these two species have
possessed this analogous trait? How do we know these traits are analogous and
not genetically related from common descent? (5 pts)
These traits seem to be instilled because of the
environmental changes and conditions of their homes. The common ancestor that
they share could have had one of these traits, or had the changing ability that
passed down in generations for centuries based on the area they developed in.
d. Provide an image of each species in this comparison. (5
pts)
I think you picked great sources for your homologous and analogous traits. I found it interesting that you chose those specific organisms and you explained each of the prompts fairly well. On another note, I believe that you gave great detail explaining the fuction and structure of each of the organisms so that someone with no knowledge of the assignment would understand.
ReplyDeletegreat choice of species, i love bears and actually never knew black bears used their fur to migrate and for hunting. thanks for the insight, very informative post.
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ReplyDeletePart (a) asks for a description of the two organisms, not just identification. Expand.
ReplyDeleteYou state that the function of these tails are for movement but different, and yet you don't explain HOW they are different, nor do you describe how they are structurally different. This couldn't just be assumed. It needed to be part of your discussion. Expand.
Yes, the common ancestor was an early reptile (not necessarily a lizard, which is a specific reptile), and the tail is a structure that can be traced back to that common ancestor. No argument that there are differences between lizards and snakes in general, but the question is about the tail and I'm still not sure what differences you are referring to here.
For your analogous pairing, again a brief description was required, not just identification.
Remember what defines an analogous trait. Analogous traits need to be the product of *convergent* evolution. They can't arise due to common descent but due to similar environmental pressures. So are you arguing that the ancestor of the polar bear and the black bear did NOT have fur and therefore the fur of these two bears is the result of independent evolution and not common descent?
This is actually an example of a homologous trait. Both of these organisms arose from an common ancestral archaic bear, who did posses fur (all mammals have fur). Due to different environments, the fur developed different expressions, both in color and in thickness and structure. This describes homology, traits arising from the duel process of common descent and divergent evolution.
Good images.