Critique the following statement: The absence of a trait cannot be used as a synapomorphy in phylogenetic analysis; only shared derived traits that are present in the clade can be used.

Video transcript

Hey everyone. Let's take a look at this question together. Which of the following can be a useful synapse morph for a clade. So let's recall what we've learned in the past about philo genetic trees and what synapse morphs are. So we know that snap amorphous referred to traits that are shared by taxi and the most common ancestor but not the previous ancestor. We also know that snap amorphous include the origin of new characteristics like the origin of limbs in tetrapod vertebrates as well as the loss of a trait like the loss of limbs in snakes or Wales. So by looking at this diagram that I drew here, we can see that this trait here is shared among species two and three from this most common ancestor. This here is a sin apa morph because that trait derived from that most recent common ancestor and is shared between species to and species three. Now what this trait is could be anything because it's just something that is shared between the two species from that most recent common ancestor, meaning that the correct answer is d all of the above because that trait could be limbs, hair, mammary glands or even something else not listed here. It's just anything that is shared by the tax a and their most common ancestor but not the previous ancestor which is this common ancestor because that trait only originates here from this most recent common ancestor and not this common ancestor. I hope you found this video to be helpful. Thank you and goodbye