Which of the following could provide the best data for determining the phylogeny of very closely related species?
a. The fossil record
b. Their morphological differences and similarities
c. A comparison of nucleotide sequences in homologous genes and mitochondrial DNA
d. A comparison of their ribosomal DNA sequences

Question

Which of the following could provide the best data for determining the phylogeny of very closely related species?

a. The fossil record

b. Their morphological differences and similarities

c. A comparison of nucleotide sequences in homologous genes and mitochondrial DNA

d. A comparison of their ribosomal DNA sequences

Accepted Answer

Hi everyone. Let's look at our next question. It says, what is the disadvantage of relying on morphological features alone in identifying evolutionary relationships among different species? So let's think about and recall what morphological features are. That would be the outward appearance as well as the internal structure of organisms. And so things that we can observe while looking at an individual at looking at its anatomy. And so we're saying, what's the disadvantage of relying on that alone without any other information when trying to determine evolutionary relationships among different species? So, let's look through our answer choices here. Well, choice A says morphology does not reflect the genetic information. Well, this is not correct, morphology is associated with a phenotype and of course the phenotype of an individual is determined by its genetics. So animals that share a great amount of genetic information and are closely related will likely have very similar morphology, very similar phenotype. So morphology can give us information about the genetics of the species. So that would not be a disadvantage of using morphology. Choice B says morphology is unique in every individual organism? Well, yes, that's true. The level like fingerprints or something. But in general, um you're going to see the same morphology among individuals of the same species. So that's not going to be a description of a disadvantage of using morphology since we'll see the same morphology among individuals of the same species compared to the morphology of individuals of different species. So that can be useful in determining evolutionary relationships. Choice. E says morphology cannot distinguish convergent and divergent evolution. Well, this is indeed going to be a disadvantage of using morphology alone. Let's recall from our content video that in convergent evolution we have similar structures so similar morphology not due to common ancestry. So if we just look at morphology alone, we'd see a batwing and a bird wing looking similar, we might conclude that they are related but they are not descended from a common ancestor. Those structures just evolved to look similar because they feel similar functions. They do similar things and will recall that divergent evolution is the opposite here and it occurs when you have different structures. So different morphology despite descent from a common ancestor. So you imagine the hand of a human being versus the flipper of a whale. They look very different. But that structure, when you look at the internal bone structure is due to descent from a common ancestor. So in the cases of convergent or divergent evolution you could be led astray if you just looked at the morphology and try to infer evolutionary relationships from that and finally, choice, the morphological features are difficult to determine. That is not a disadvantage of morphology because we can observe morphological features just by looking at the anatomy. Looking at the appearance of the species, we don't need to do genetic analysis or other things like that. So again, what is the disadvantage of relying on morphological features alone and identifying evolutionary relationships among different species choice. C morphology cannot distinguish convergent and divergent evolution? See you in the next video.

Verified video answer for a similar problem:

Key Concepts

Phylogeny

Molecular Phylogenetics

Homologous Genes