Which of the following nested monophyletic groups are correctly organized from largest (most inclusive) to smallest (least inclusive), showing your place in the tree of life?


a. Deuterostomes>Chordates>Vertebrates>Mammals
b. Animals>Mammals>Vertebrates>Primates
c. Chordates>Primates>Mammals>Hominins

Verified step by step guidance

1. Identify the meaning of 'monophyletic group': A monophyletic group, or clade, is a group of organisms that consists of all the descendants of a common ancestor.
2. Understand the hierarchy of biological classification: The hierarchy typically follows this pattern from largest to smallest: Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.
3. Analyze each option to determine if the groups are listed from most inclusive (largest) to least inclusive (smallest) based on the known biological classification hierarchy.
4. Option a: Deuterostomes > Chordates > Vertebrates > Mammals. Here, Deuterostomes is a superphylum that includes several phyla including Chordata. Chordates include all vertebrates and some other closely related invertebrates. Vertebrates are a subphylum of chordates, and mammals are a class within the vertebrates.
5. Option b: Animals > Mammals > Vertebrates > Primates. This sequence is incorrect because Primates are a part of the class Mammalia, and thus should not be placed after Vertebrates. Mammals are a class within the subphylum Vertebrates.
6. Option c: Chordates > Primates > Mammals > Hominins. This sequence is incorrect because Primates are an order within the class Mammalia, and Hominins are a tribe within the family Hominidae of the order Primates. Thus, the order should be Chordates > Mammals > Primates > Hominins.

Key Concepts

Monophyletic Groups

Monophyletic groups, or clades, consist of an ancestor and all its descendants, representing a complete branch on the tree of life. Understanding these groups is essential for classifying organisms based on evolutionary relationships. For example, the group 'Mammals' includes all species that share a common ancestor that was a mammal, distinguishing them from other vertebrates.

Taxonomic Hierarchy

The taxonomic hierarchy is a system used to organize biological diversity into ranked categories, from broad to specific. The main levels include domain, kingdom, phylum, class, order, family, genus, and species. This hierarchy helps in understanding the relationships and classifications of organisms, such as how 'Chordates' encompass a wide range of species, including 'Mammals' and 'Primates.'

Nested Hierarchies

Nested hierarchies refer to the way in which groups of organisms are organized within larger groups, where each level of classification is contained within the broader category. This concept is crucial for understanding evolutionary relationships, as it illustrates how specific groups, like 'Mammals,' fit within larger categories, such as 'Vertebrates' and 'Deuterostomes,' reflecting their evolutionary lineage.