HOMOLOGUS TRAITS
a. After doing some research, I found
really interesting that humans and dogs had any kind of ancestral connection. Humans
are
bipedal primates belonging to the genus Homo, especially Homo sapiens. In taxonomy, humans belong to the family hominidae, of the primates,
under class mammalia of phylum chordata.
Dogs are distinguished for intelligence, docility, and attachment to man,
and is mammal too.
b. Humans and dogs have similar pelvises, but
they don’t look alike and have different functions. The canine pelvis is long and narrow while the human pelvis is
short and broad. In humans, the pelvis
provides a location for the large muscles of the lower body to connect, giving
humans the ability to walk, run, sit and kneel.
In dogs, the pelvis encircles the pelvic cavity and has several functions
including protecting the pelvic viscera, and the reproductive and urinary
organs. The pelvis is also essential in locomotion and posture. In addition to similar
bones structures, they also have similar upper limb muscles. We can determine whether a muscle is
homologous by looking at which bones it attaches to and what function it
performs.
c. Well, we don’t know
the common ancestor that connect this two, but both are mammals that means they
have backbones or spine, and other characteristics in common.
a.
After
doing some research I also found really interesting putting sharks and dolphins
together and see what makes them so different. Sharks are a long-bodied chiefly
marine fish with a cartilaginous skeleton, a prominent dorsal fin, and
toothlike scales. Most sharks are predatory, although the largest kinds feed on
plankton. Dolphins are highly intelligent marine mammals and are part
of the family of toothed whales that includes orcas and pilot whales. They are
found worldwide, mostly in shallow seas of the continental shelves, and are
carnivores, mostly eating fish and squid.
b.
In Sharks and Dolphins, the dorsal fin keeps them upright, it
prevents the body from tipping or rolling over, providing stability while
swimming. They are
anatomically different. The dorsal fin of sharks is rigid, and supported by
cartilage internally. The dorsal fin of dolphins has no internal support. They
are held erect by collagen fibers in the outside skin only.
c.
If
we go back in time, maybe we could find an animal similar to both, but dolphins
evolved from mammals and sharks evolved from fish, both have different and
similar characteristic and have different ancestors. Both developed their
similar fins due to a common environmental pressure.
i liked that image, because we can clearly see the difference in the fins of sharks and dolphins.
Okay on your opening description of your homologous species, but let's keep the descriptions purely biological. Kind of biased to define dogs in terms of their relationship to man. They have a long history long before man came on the scene.
ReplyDeleteOkay on your description of structure and function, but missing is a key function of the human pelvis which has a great impact on its structure, namely how it needs to cradle the internal organs in a bipedal organism. For some reason, you high light this in the dog, but it is the human where this really shows the impact of organ support. We will see more of this later in the semester when we talk about bipedal evolution.
Correct, they are both mammals but how can you use that information to confirm that these are homologous traits? We know from fossil evidence that the common mammalian ancestor possessed the primitive pelvic structure and passed that trait onto these two descendants with variation arising due to different environments and functions. That is what we need to know to confirm that these are homologous traits.
Good opening description of your analogous species pairing.
In general, good discussion of your analogous traits, though keep in mind here that what is important are the similarities due to similar selection pressures. We already expect the differences since they aren't genetically related, correct?
Actually, the ancestry issue is more complicated because the common ancestor was actually a fish who possessed the trait in question and also passed that trait onto extant shark species. So the question is, did the dolphin also inherit it's fin from that common ancestor? Dolphins "fins" evolved after dolphins split off from terrestrial mammals, i.e., long after the split with ancient fish. This provides us with the evidence we need to confirm that this trait did evolve independently in at least one of these organisms, making these traits analogous.
Good images.
Hello Ana,
ReplyDeleteI think the information that you gathered on a human and a dog was very interesting. I like how your pictures really capture the comparisons between each species. I also picked the sharks and dolphins for the analogous traits and also found some very interesting information. I think their common ancestor is a reptile. I could be wrong but I see that you didn't put that. Anyways, I really enjoyed your blog post.