The vast majority of animals that ever existed are now extinct, but Tereza Jezkova and John Wiens wondered which variables were most important in driving the diversification of species that exist today. Why are there so many species in some phyla, such as Cnidaria (see photo), but so few in others, such as Ctenophora? The researchers know that correlation does not equal causation. However, can the absence of a correlation enable you to reject a hypothesis of causation? How would the R2 values be different in a scenario where a single trait was important to diversification in many phyla versus a scenario where different traits were important to diversification in different phyla?

Video transcript

Hi, everyone. Let's look at the next question. An approach to biological classification in which organisms are categorized into groups based on hypotheses of most recent common ancestry is termed as well. Let's look through our answer. Choices here. Choice A is embryology. So embryology we can recall is the study of embryos and their development. This is often part of uh categorizing organisms into groups based on most most recent ancestry because you can look at comparative embryonic development across species. But this is not the approach to classification. This is just one element of it. Uh specifically the study of embryos in their development. So that is not our correct answer. Choice B says ecology, um ecology is the study of the relationships oops between living organisms and there physical surroundings. So not what we're looking for here. So choice B is not our answer. Either. Choice C is clits and clits is indeed uh an approach to biological classification in which organisms are categorized based on hypotheses about their most recent common ancestry. So Choice C is Clits is going to be our answer. Uh groups uh organisms into Collado grams which are groups with a common ancestor and uses many different data from different fields including embryology, including genetics, to infer uh how the organisms are related to each other and what their most recent common ancestor is. Finally, we have choice. D anatomy and anatomy of course, is that branch of study concerned with the identification and description of the body structures of living organisms. So just like embryology, anatomy will be a part of clots because you'll look at comparative anatomy of species to look and see if there was perhaps evolution from a structure in a common ancestor. But it's not the description of the overall approach to classification, which is again clits. So the approach to biological classification in which we classify or categorize organisms based on inferences about their most recent common ancestry is choice clits. See you in the next video.