1.
Homologous traits
a.
The two species that share homologous structures
are the human arm and a cat leg. Humans, or Homo Sapiens, are from the
Hominidae family and the only species of the Homo genus. Humans are a distinct
species for their enlarged brains and brain activity. The common cat, or Felis
Catus, is from the family Felidae. Species in this family have similar anatomy,
which consists of: flexible bodies, quick reflexes, sharp claws and teeth.
b.
The bones that compose the arm of a human and
cat are composed of all the same bones: Humerus, radius, ulna, carpal,
metacarpal, and phalanges. There are differences in structure between the
individual bones such as length, width, and girth. The function of the Human
arm is to move and pick things up, while the leg of a cat is to help the cat
run, jump, etc. The structures of the bones appear strikingly similar, but
function differently due to evolution and the different environments each
species live.
c. Considering the similarity of bone structure between the two species, there must be a common ancestor between the two species. the common ancestor of the human and cat is most likely to have been a land mammal.
d.
2.
Analogous structures
a.
The two species that have analogous traits are
the pectoral fins of a dolphin and shark. Dolphins are from the family
Delphinidae and are one of the largest species in the Catacea order, which
include marine mammals like whales and other porpoises. Their high intelligence
levels as well as their tail fin, dorsal fin, and pectoral fins characterize
dolphins from other species. Sharks are from the clade Selachimorpha. There are
characterized by their gills, pectoral fins unattached to their head, and a
cartilaginous skeleton.
b.
The pectoral fin of both the shark and dolphin
serve the same function of aiding the animal when it is swimming. They are also
very similar in structure and appearance since both species live in water.
c.
One of the biggest difference is the fact that a dolphins are mammals and sharks are fish. Besides the pectoral fins, sharks and dolphins have some major differences when it comes to anatomy. However, I think the
common ancestor of the dolphin and shark did share this analogous trait. It was
perhaps a species that lived in the water.
d.
Good choice of homologous traits and good description of their similarities and variations due to environmental differences.
ReplyDelete"Considering the similarity of bone structure between the two species, there must be a common ancestor between the two species."
It is true that their bone structure is the same and that they share a common ancestor, but understand that all organisms share a common ancestor if you go back far enough in time. They don't need a similar skeletal structure for this to be true. The key is that the common skeletal structure was inherited from this common ancestor. That is true for these two species which is why this trait is homologous.
Good job on the analogous trait. I agree that the common ancestor (who was a cartilagenous fish) also possessed this trait. So why isn't this trait a homologous trait? Isn't that part of the criteria of a homolog? How could this be an analog?
What a great comparison on the Analogous trait! I think most people always assume the dolphin and shark are directly related just because of their dorsal fin. Considering their common ancestor possessed a pectoral fin, I would love to know that's actually not considered to be a homologous trait?
ReplyDelete