Blog Post #3
Homologous: The
two species that share a homologous trait are a human and a dolphin. The arm of
a human and the fin of a dolphin both share the same homologous structure.
Homologous is the same structure, different function. In this case both the
human arm and the fin of a dolphin share the same structure, but different
function. The structure of the fin of a dolphin is composed of the same
structure of a human hand. Both share a humerus, ulna, phalanges, and ball and
socket joints. Although their structure is alike their function is different.
The function of the human arm is to be able to do things such as, picking stuff
up, writing, lifting, and many other things. The function of the dolphin
flipper is to help keep balance and help the dolphin to stop and turn. Both
Species share a common ancestor, however over the years of evolution this
similar trait has evolved into different functions. Given that both species
have a humerus, I would say the common ancestor is a mammal.
Analogous: Two different species that share analogous
traits are the flying squirrel and the sugar glider. Both species contain a
couple similarities, like the big eyes and contain a piece of skin stretched between
their arms and legs to help them glide through the air. There are also some key
differences in these creatures. First the flying squirrel is a placental
mammal, meaning the baby spends all the time developing in the womb being fed
by the placenta. Sugar gliders are marsupial animals, which means they only
spend a little bit of time developing in the mother’s womb and continues to
develop outside the mom’s womb. These species share similarities due to the
fact that they both adapted from lineages with the same lifestyle function. Including
gliding from tree to tree and being able to see at night. They are different
because they live in two different parts of the world. The differences in
territories creates some differences in their behaviors. One being that sugar
gliders have scent glands to distinguish their territories as flying squirrels
do not have this function. Also sugar gliders very rarely set foot on ground,
and flying squirrels will. My research concludes that the adaption of similar traits
occurred separately and was not passed down by a shared ancestor. I was unable to find a definite answer if their
ancestors shared the same analogous trait.
I think your homologous example is so great. I chose that of a cat and a whale, which is part of the same category of the dolphin and human. I think that your example of the sugar glider and flying squirrel are great since you would think they're the same, but they in fact are pretty different. Good work!
ReplyDeleteThis post was definitely one I learned the most in thats for sure. Never would I have thought about the similarities between a dolphin and a human and the functions they share. Also, I never would have thought to choose a sugar glider and a flying squirrel. This blog post was very detailed and had a lot of information, yet very interesting. Definitely taking in a lot of information with this post. Thank you!
ReplyDeleteGreat post! I was unaware of the functions humans and dolphins share. Your blog was very informative and you did a great job. keep it up!
ReplyDeleteI think this was a great post, i too am still a little confused on what humans and dolphins share but overall it looks like you did your research
ReplyDeleteGood opening description and explanation of your homologous pairing.
ReplyDeleteWith regard to ancestry:
"Given that both species have a humerus, I would say the common ancestor is a mammal. "
We don't the humerus to say this. Both humans and dolphins are themselves mammals. That means their ancestor HAD to be an archaic mammal. And we know from fossil evidence that the archaic mammalian ancestor possessed the ancestral limb structure, passing it on to their descendants. That is the information we need to know to confirm that these traits are the result of common descent and are therefore homologs.
Great example of analogous traits! One of my favorites. Good description and explanation for these traits.
Yes, these traits did arise independently but a little reasoning was all that was needed to confirm this. Both of these creatures belong to the group Rodentia, which is just a huge group of organisms. Out of all those rodents, these are the only two to have developed these skin flaps for gliding. That indicates "derived" traits, not ancestral traits, meaning they are unique traits developed just by these two lines of rodents, not something they inherited by their common ancestor. If they did inherit from a common ancestor, this trait would be much more wide-spread. We also know from fossil evidence that this was not an ancestral trait. That is what we needed to know to confirm these are analogous traits.
Good images.