Analogy and Homology
1.
A.
Two species that possess a homologous trait are
humans and the dolphin.
B.
The homologous trait that each species shares is
the human arm and the dolphin fin. Though each one is used differently. The dolphin
fin contains bones, it curves back and pointed at the tip. The human arm also contains bone but has
joints at the elbow, wrist and fingers. The
fin is used to turn, stop, balance and help with body heat. The human arm is used to hold, grab, push, pull, and many other things. The reason
for the differences in the dolphins fin and the human arm is due to different
functions in their respective environments.
C.
Dolphins and humans are both mammals and have a
common ancestor, tetrapods which possessed this homologous trait. It is known that tetrapods possessed this
homologous trait through cladistic analysis.
2.
A.
Two different species that possess the analogous
trait are the duck billed platypus and the duck.
B.
The analogous trait that the duck billed
platypus and the duck share is that they both lay eggs. The duck billed platypus looks like a duck,
has a bill like a duck and webbed feet, but is a mammal that lays eggs. This is more commonly seen in birds.
C.
Although the duck and the platypus may look very
similar and both lay eggs they do not share a common ancestor. The platypus is a mammal and the duck is a
bird that has wings and can fly. In this
case the traits are analogous.
I liked your comparison of human and dolphin homologous traits. I enjoyed your comparison of the dolphin fins and the human arm, but I felt you could have gone a bit more in depth with what bones are similar to each other, like both have humerus bones in their arm/pectoral fin.
ReplyDeleteI thought your pick of the platypus and duck was very unique and clever. I hadn't realized how similar the platypus and duck look to each other.
Part A asks for a description, not just identification of the species.
ReplyDeleteGood description of the homologous traits. Are the bones in the forelimb of the human the dolphin homologous as well, i.e., are they essentially the same bones (ulna, radius, humerus, etc.)? Note that there are joints in the dolphin as well, they just aren't as flexible.
We can be a little more specific on the ancestor and you allude to it at the beginning of this section. Both of these organisms arose from a common mammalian ancestor which possessed the ancestral forelimb structure. This structure was passed onto these two descendents. This is what we need to do to confirm that these are homologs.
Good choice on your analogous traits. A unique pairing. You don't quite finish the though on ancestry. The common ancestor of mammals and birds is an archaic reptile which may or may not have been an egg-layer. But regardless, we know that mammals in general do not lay eggs. This confirms that the trait arose independently in the platypus, which is what we need to know to demonstrate that these traits are analogous and not genetically related through descent.
Good images.
Bravo Anthony, I enjoyed your post as well especially since its and old fashion comparison. They say humans and dolphins share many similarities from brain function to family or social dealing ls so the forelimb being the same kinda surprised me. I love you analogous comparison. Not,many people would choose to talk about the platypus. Yes they might look alike but one has the body of a beaver if you will and the the back is similar to that of a duck and it's different size.
ReplyDeleteBravo Anthony, I enjoyed your post as well especially since its and old fashion comparison. They say humans and dolphins share many similarities from brain function to family or social dealing ls so the forelimb being the same kinda surprised me. I love you analogous comparison. Not,many people would choose to talk about the platypus. Yes they might look alike but one has the body of a beaver if you will and the the back is similar to that of a duck and it's different size.
ReplyDelete