Analogy & Homology
Homologous Species: The Cat and The Bat
a. Bats and cats are two different species with
homologous traits.
b. A bat’s wing in
comparison to a cat’s leg is similar because of their skeletal components. Both
structures have a humerus, radius, ulna, carpals, metacarpals and phalanges.
However, even though they have homologous traits, they are each structured
function differently. A bat’s skeletal structure has much longer metacarpals
and phalanges then that of a cat, which helps spread their wings in order to
fly. A cat doesn’t have wings therefor does not need to fly. Their bones appear
a lot thicker and close together, which is helpful because they need that
strength to support themselves while they walk and jump from place to place. So
even though these two species contain homologous traits, their structures are
completely different because they both have different uses for these traits.
c. Even though
the bat and the cat have homologous traits, they don’t necessarily have the
exact same ancestor. They do however come from the same structures within the
embryo. So this would conclude that because they have homologous structures,
they come from a common ancestor.
d.
Analogous Species: The Shark and The Dolphin
b. Although dolphins are mammals and sharks are fish, both have a torpedo
shaped body and dorsal fins that are caused by convergent evolution. They both
need their fins in order to maintain balance while swimming.
c. There hasn’t been
any recent discovery on a common ancestor for the dolphin and shark. I feel
that hypothetically, if they did have a common ancestor, it would have had some
sort of fin structure. Both organisms have fins so it’s a great possibility
that whatever they both trace back too also had a similar structure.
d.
posted by Unknown @ 11:29 PM
2 Comments
2 Comments:
Very good description and explanation of your homologous trait. For some reason, this sentence caught my attention:
"A cat doesn’t have wings therefor does not need to fly."
From an evolutionary perspective, watch your causation. A cat doesn't have wings, which only indicates that it CAN'T fly. It may well be that it could have benefitted from the ability to fly but evolution is limited in what it can produce with a given set of genes. It took the path that worked for cats. Nothing wrong, just offering a scientific/biological perspective.
"Even though the bat and the cat have homologous traits, they don’t necessarily have the exact same ancestor."
If you are talking about an individual organism, I will give you that, but at a species level, that is exactly what we are likely talking about, in terms of the common ancestor of all mammals (since both are mammals), though I like the use of embryology to support your conclusion.
http://www.livescience.com/26929-mama-first-ancestor-placental-mammals.html
Looks like you originally started out comparing penguins and dolphins and switched midway to a shark/dolphin comparison, which also works.
All organisms have a common ancestor if you go back far enough. In this case it would have been an early cartilagenous fish. The shark has not changed much from that early ancestor, but the dolphin has gone that long route through bony fish, amphibians, reptiles, and mammals to what it is today. But remember that you are presenting analogous traits. If they DID both inherit these traits from that common ancestor, wouldn't that make these homologous traits?
Fortunately, we know that the dolphin developed these traits independently, after it evolved from land mammals and made the move to the ocean, developing the similar structures you see in sharks to help it in the aquatic environment. That independent development of the traits means that they are not genetically related and therefore are analogs.
Hi Aryana! Your comparison between a cat and a bat is something that I never would've thought to compare, but you're definitely right about their similarities. I think that a common ancestor, however, might be the broad group of early mammals, since they are both mammals, even though the bat's evolution diverged later on and gave it wings.
And with your connection between sharks and dolphins, I think that a broad common ancestor would be an ancient fish, because far back on even our evolutionary track, we all evolved from fish. So I think it's true to say that their common ancestor did have fins in common, which reemerged in the dolphin species as they further evolved from land mammals back into sea mammals.
Post a Comment
Subscribe to Post Comments [Atom]
<< Home