Analogy/Homonology
1a). The two species that posses the homologous traits are
humans and snakes. Both of us have pelvic bones. Its hard to imagine that we are similar in any
way to snakes.
b). The homologous
trait in human and snakes are the pelvic bones. Snakes don’t really use it
because they don’t have any legs they just have it there because of their
ancient relatives; they have no need for it. While humans have it because we
need to get around. Without the pelvic bone our legs would be of no use to us
at all making it harder for all human being survival. While snakes have no use
or need for their pelvic bone humans needed to insure their survival.
c).Snakes and humans
common ancestor is amniote, a vertebrate. This was what created more
vertebrates.
d).
2a).After doing some research I was able to find two
different species with the analogous trait. Both of these animals have a hardshells
on top of them that protects them from depredators.
b). The analogous trait that that this two animals have in
common is their shell. The difference between this two species is that snails
are slimy and are able to slide to get around and turtles have skin like that
of a reptile and have legs that help them to walk around.
c) In my opinion, I believe that this two species ancestor didn’t
have this analogous trait before, I will assume that they developed it over
time due to environmental change and to protect themselves from the predators
due to how slow they move.
The traits for these animals are not genetically related because
they don’t come from a different ancestor, turtles come from reptiles and
snails from slimy mollusks.
d).
I was so surprised at what your animals were for the homologous trait. Who would have ever known that snakes and humans could be similar in even the least bit. Very knowledgeable!
ReplyDeleteA little on the large side, but otherwise, I loved your images!
ReplyDeleteI would have liked more offered in your initial description of your species pairing for both your homologous and analogous pairings. A little sparse. It would have helped explain their traits if we had understood the species better.
This is a valid homologous trait. My only quibble is that you insist that the snake pelvis no longer has a function. It may not have a locomotor function but it does have a reproductive function during mating. Additionally, while the image of the snake skeleton was very cool, it would have been better to use one that actually showed the image of the snake pelvis, or "spurs". Here's one:
http://4.bp.blogspot.com/-QEWak5nsnJk/VfJ0BXD8UbI/AAAAAAAAACg/nZTdExPBheE/s1600/snakes.jpg
"Amniotes" are just organisms who reproduce by forming eggs and laying them on land or retaining them internally, including reptiles, mammals and birds. This doesn't tell us anything phylogenetically, just reproductively.
Likewise, "vertebrates" are anything with a vertebral column. That's a lot of organisms. Can we narrow that down a bit? We know that snakes are reptiles, and that reptiles gave rise to mammals and then to hominids. So we know that the common ancestor was an archaic reptile. We know from the fossil record that ancestral reptiles possessed the tetrapodal limb structure you are highlighting and pass it onto these two lines of descent, where differences in environment and function produced structural differences via divergent evolution. That is the information we know to confirm that these traits are indeed homologous.
Great choice of analogous trait, and good description of the similar selection pressures that would have produced this trait in two different species.
"In my opinion, I believe that this two species ancestor didn’t have this analogous trait before"
For this assignment, we weren't looking for your opinion or your beliefs on the topic. We were looking for evidence that supported your claim that these traits are analogous.
There is some evidence to confirm that the trait of the shell evolved relatively recently from non-shelled slug-like creature, similar to banana slugs, and there is even more evidence of the independent evolution of the turtle and tortoise shell from their non-shelled reptilian ancestors. This is what we need to know to confirm that these traits were not inherited from a common ancestor but through parallel (or convergent) evolution.