For your homologous traits provide the following information:
Briefly describe the two different
species that possess the homologous trait
A whale
is a mammal that lives in the ocean. Whales breath air, are warm blooded and
give birth to live offspring, which they nurse. Whales are social animal and
travel in pods, are able to stay under water for 15 minutes or up to an hour if
avoiding danger. There is an interesting difference between Baleen Whales who
swim with their mouth open and ‘comb’ out anything that is not food and teethed
whales that are active hunters such as the Orca that can eat seals, other
whales or sharks.
Example of male and female whale
Example of male and female human
A human is a mammal that lives on land. They are bipedalists, walking on two feet and upright. Humans, like whales are warm blooded, breath air and nurse their live born offspring. Generally humans are social creatures and no matter how much danger they face they cannot stay under water for longer periods of time.
According
to the Mount Sinai School of Medicine in New York, who made a comparison
between the neurons found in both cetacean species and apes/humans revealed a ”convergent
evolution of the brain maybe by the development of complex behavior.” (Source:
news.softpedia.com)
While this is an ongoing research it has been established throughout the scientific society
that whales do have a way to communicate within their species, a sign of higher
intelligence that humans also express.
Describe the
homologous trait of each species, focusing on the difference in its structure
and function of the trait. Why do the homologous traits exhibit differences
between the two species? Make sure your explanation is clear and complete
The
homologous trait in the human and whale is the forearm limb. As the images show, the organs are dissimilar
in shape, size and function but their basic plan and development are similar. The the human arm, which is in proportion with the rest of the
human body is unlike the whale’s limb which is not proportional at all.
The
following image (middle) is very impressive in my opinion, as one may easily mistake the
whale’s limb with a human hand. It shows how very similar the structure of each limb is. However, the whale is not able to grab anything and is restricted in its function.
The bones in the vertebrate forelimb of a whale are relatively compact and do not move within the flipper. Therefore it is great for swimming and provides them with a strong paddle which allows the whale to control the direction of motion.
The forelimbs
of a human are slender, long, mobile and since they are walking upright, do not
bare any weight during movement. The fingers and thumbs allow fine motor skills
and the shoulder socket allows the limb a range of motion of 360°.
Who was (generally, not specifically) the
common ancestor of these two species and how do you know that ancestor
possessed this homologous trait?
The
common ancestor is a water creature that entered the land. I chose the whale
and the human, because I think that it shows the relation between water organism
and land organism the best. I also like that while the structure of the limb is
similar, its use is completely different.
I know
that the common ancestor had forelimbs as well, as they used it to move
forward and it is a trait that was passed on from an ancestor to a descendant,
the qualifying key to identifying a homologous trait. The anatomical comparison
above is a good example for Darwin’s statement of “descent with modification”
and the evolutionary tree below shows his “branching out of species from a
common ancestor”.
Provide an image of each species in
this comparison.
The following two images show the
variety we can witness in whales and humans in its species
Variety in the species of whales
Variety in the species of humans
For your analogous traits provide
the following information:
Briefly describe the two different
species that possess the analogous trait
The species I chose for the analogous trait are
the Flying Squirrel and the Sugar Glider. The analogous trait both species have
is the glide membrane.
The Flying Squirrel is part of the animal
kingdom, classified as a mammal and in the Rodent order. They breed about twice
per year. The gestation time is about 40 days at the end of which the female
gives birth to 2 to 7 blind and naked babies. Within the first month the babies
develop fur and open their eyes and by the second month they are able to begin
to glide and forage with their mother.
Flying Squirrels are nocturnal and eat nuts,
seeds, fruits, berries, insects as well as bird eggs, making them omnivorous.
They grow to be around 8 to 11 inches and carry a weight of about 8 ounces. Their glide membrane allows them to glide at a
top speed of 15 mph and the longest recorded flight measured 90 meters (270
feet). They direct their flight path by tensing and turning their legs and body
and by flapping their tail. In order to land they flip up their tails and
arches back the body to slow down the flight.
The other species I chose is a Sugar Glider. It
is classified as a marsupial. Their gestation time is about 16 days. Like Kangaroos,
the sugar gliders have a pouch in which the prematurely born baby lives for
60-70 days until it leaves when it is able to survive outside the pouch at
about 4 month of age. A full-grown Sugar glider weighs only about 4 ounces. They
live in trees, barely touch the ground ad live in groups of 15-30 at a time,
marking their nests with urine. Like the
Flying Squirrel the Sugar glider has a gliding membrane located from its wrists
to its ankles and it can open up to slow down. The curvature of the membrane is
changed by movement of the legs in order to regulate the glide. It also uses
its long tail to function as a rudder.
Describe
the analogous trait of each species, focusing on the similarities in its
structure and function of the trait. Clearly explain why these analogous traits
exhibits similarities between the two species
Both the Flying Squirrel and the Sugar glider
use their membranes at the side of their bodies to ‘unfold’ into a wing or parachute.
Both species are using their tails to control the flight path and also to
function as a brake. The species
developed the extra skin that allows them to glide, as they have a lot of
predators and not enough means to escape them.
Sugar Gliders and Flying Squirrels are the only
living gliding mammals (besides the “flying lemur). They appear to be similar,
but are in two different classes, with the Sugar Glider being related to the Kangaroo
as a marsupial and the Flying Squirrel being a placental mammal. The
similarities are due to similar adaptation that shows evolution independently
in different groups.
Did
the common ancestor of these two species possess this analogous trait? Why or
why not?
The
common ancestor of these two species did not possess the analogous trait. Both species are very distantly related to the
rat like mammal and it is not likely that the ancestor had extra skin between
its limbs like the modern animals inherited the trait. Both species were facing
similar problems, challenges and opportunities and evolution shaped them in
similar ways resulting in their analogous structures.
The
common ancestor of these two species did not possess the analogous trait. Both species are very distantly related to the
rat like mammal and it is not likely that the ancestor had extra skin between
its limbs like the modern animals inherited the trait. Both species were facing
similar problems, challenges and opportunities and evolution shaped them in
similar ways resulting in their analogous structures.
Provide an image of each species in this comparison.
Since I have already provided an image of each
species with my previous statements, I am including two video links that I have
found online that show the creatures I chose in action.
The Sugar Glider and
the Flying Squirrel
Andrea,
ReplyDeleteAll I have to say is WOW!!
Excellent I love how you compared humans to whales. I never knew anything about that. Now thinking bout animals are a lot like humans
Mimi, thanks. I have done a study on Orcas as whales fascinate me and this seemed to be a good comparison. I wanted to compare the human eye lense with that of a fly for analogous traits but then got into the flying squirrels. Did you know that people keep them as pets? Tempting, but while it is cute it is still a rodent. :-)
ReplyDeleteGreat (and extensive) background on your homologous traits and the related organisms. Good discussion on their ancestry and how that supports the claim of homology. One key is that both of these organisms are mammals and they share the ancestral mammalian forelimb structure, the rudiments of which are also shared by reptiles and amphibians. This is a straightforward way of demonstrating that these traits are, indeed, homologs.
ReplyDeleteThe glide membrane is an excellent example of analogous trait. Good job with your description of the organisms and the similarities in their traits rooted in the similar environmental pressures. Great discussion on the ancestry as well.
Great post.
Thanks Prof Rodriguez. I have read a few other posts and it is really inspiring to see all the findings and similarities to all other species. I have looked up a lot of them just to see close up images or read up on why they have certain traits.
ReplyDeleteBest,
Andrea