A. Homologous Traits:
Koalas and kangaroos are
an example of having homologous traits. They are two different species that share
the similar trait which is marsupials, also known as their
pouches.
Koalas and kangaroos both have pouches where they keep, feed, and
grow their babies. These two species have a pouch because they give birth early
so when the baby is born, it is not fully developed yet. A koalas’ pouch is
lower and more downward facing towards the bottom of their bodies. As for a kangaroo’s pouch, it is located in the abdominal area opening upwards at the
top. The differences in the pouch and where it is located is possibly because
of their lifestyle. Koalas climb from tree to tree, which is why they have strong
claws, and if the koala’s pouch was opening upwards at the top, the baby might
fall out. As for kangaroos, they have strong powerful hind legs and feet which
is used a lot in order to get from one place to another, that's probably why
the pouch is located upwards at the top.
Due to the similarities of the pouches;
I believe that there is a common ancestor to these species.
B.
Analogous Traits:
Crickets and kangaroos
are an example of having analogous traits. They both perform similar jobs and have
similar structured hind legs but they have different origins.
Crickets and
kangaroos often use their hind legs for jumping from one place to another. The
hind legs of these two have a similar certain muscles and tensions that aid the
species to jump. The hind legs are the strongest and most powerful features of
these species. A kangaroo is a mammal, but a cricket is an insect yet they have
similar hind legs.
I tried to find a common ancestor for these two but I wasn't able to. Maybe they might not have a common ancestor.
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Good unique choice of traits and good discussion on their similarities and differences.
ReplyDeleteYou can't look at the similarities and decide that they must have had a common ancestor. That is the same problem as looking at birds and bats and deciding they must have a common ancestor because of commonalities in their wing structure.
We know that the pouches of kangeroos and koala's are homologs because of other evidence, such as genetic relationships between these two and fossil evidence of the ancestors and geographical patterns of descent. Then we take that information and look at the pouches and conclude that they are homologs.... not the other way around.
I like how you managed to use kangaroos for both sets of traits!
All organisms have a common ancestor if you look back far enough. The key here is do we know if either species developed their trait independently from the other. In this case, we know the kangaroo developed this trait independently... it is a "derived trait" of this species. So that means these traits must be analogous, even if crickets did inherit their jumping ability from the common ancestor.
Professor,
DeleteI admit, the ancestor was a bit confusing for me but thank you Professor for making it more clear. The way you explained it helped me understand it a little better.
- Warunee Kamolrat
Thank you for the response.
DeleteWarunee,
ReplyDeleteI thought it was very interesting that you chose koalas and kangaroos for the homologous traits. For some reason I had no idea that koalas had pouches! I like the way you compared and contrasted their pouches because it made sense why koalas have pouches facing downward and kangaroos is facing upward since they hop around and travel on foot. It was a very interesting assignment to read. Thank you!
- Jackie
Jackie,
DeleteThank you for your feedback! I'm glad you enjoyed reading it!
- Warunee Kamolrat