Two species that possess the homologous trait are frogs and
lizards. Both have a body structure with the same genetic bases, which was
inherited from a common ancestor. The limbs may look pretty different on the
outside and vary in function but they have similar skeletal structures. Since
both have different functions, this makes them possess homologous structures.
Because of their similar structures, this suggests that both species evolved
from a similar/common ancestor.
Two species that possess the analogous trait are bats and
birds. Not the species themselves, but their wings. They serve the same
function in each species but evolved independently rather than from the same
embryological material or even from the same structures in a common ancestor. Butterflies
and bats are a product of separate evolutionary responses to roughly similar
functional demands. When it comes to the ancestry of the bat and the butterfly,
each developed their wings separately and independently. Therefore, the common
ancestor of each species did possess the analogous trait and they are each a
result of separate evolutionary responses. The have the same function, but not necessarily the same
ancestry.
Let's start with the homology: Yes, the overall structure of the frog and lizard body shares similarities because of common ancestry. But past that, you left some questions wide open.
ReplyDeleteAre you talking about just the limbs? Or a specific trait of the limbs? Or just the body in general? This need clarification.
You say they share commonalities in structure but don't describe those commonalities. Likewise, you allude to functional differences. What are those differences?
Can you generally identify the common ancestor?
RE the analogy:
When we talk about the "common ancestor" we are talking one species that was an ancestor for both, so we won't be looking for two separate common ancestors, just one, and that common ancestor WON'T share the trait with both if these are indeed analogies.
We are also not looking for shared embryological material, but whether or not they have shared genetic material. Two different things.
The bird and bad wings are good analogies and do indeed share a common function. Can you describe their structural differences? Can you speculate as to the common ancestor of these two? Do you have to go back to mammals or perhaps further back to reptiles?
Good images.
I like your idea about comparing the butterfly wings and bird wings. They obviously do have the same function, but the butterfly's wings are so much more delicate so I suspect that they don't have bones like I believe the bird does. Do you know how the butterfly's wings keep their shape?
ReplyDeleteAnd since butterflies start out their lives as a caterpillar I don't think that the two have a common ancestor, but I could be wrong.
I liked the subjects that you chose. Frogs and lizards are obviously fairly similar and it would not be difficult to make a connection between their ancestry, but the bat and the bird are a bit trickier.The wings, two things that have seemingly the same function, but are different in physicality. However, it would seem that these to species have very little in common other than sharing what to the naked eye, would seem a similar trait. I liked your outline and the specifics, it wasn't difficult to follow.
ReplyDelete