Question

A monophyletic group is a a. phylogenetic tree b. shared derived trait c. character state d. clade

Short answer

A monophyletic group is a \(d. \text{clade}\).

Step-by-step solution

Understand the term "monophyletic group"

A monophyletic group is a group of organisms that includes a common ancestor and all of its descendants. In other words, it consists of all organisms that share a common evolutionary history.

Analyze the options

a. Phylogenetic tree: A phylogenetic tree is a diagram that represents the evolutionary relationships among different organisms. It can be used to visualize the relationships between the organisms, but it is not the term for a monophyletic group itself. b. Shared derived trait: A shared derived trait is a characteristic that is unique to a certain group of organisms and is inherited from their common ancestor. While this trait can help identify a monophyletic group, it is not the term for the group itself. c. Character state: A character state is a variation of a trait or characteristic found in different organisms. Like shared derived traits, character states can help identify monophyletic groups, but they are not the term for the group itself. d. Clade: A clade is a group of organisms that includes a single common ancestor and all of its descendants, making it synonymous with a monophyletic group.

Choose the correct term for monophyletic group

Based on the analysis of the options, the correct term for a monophyletic group is \(d. \text{clade}\).

Key concepts

Clade

In biology, a clade is a term that you will often come across while studying evolutionary biology. A clade is essentially synonymous with a monophyletic group. This means it consists of all the organisms that have evolved from a common ancestor. Here are some important points to remember about clades:

• A clade includes a common ancestor and all of its descendants, without leaving any out.
• Clades are formed based on shared characteristics inherited from this common ancestor.
• Because they reflect evolutionary history, clades are a central unit of organizing biological diversity.

Visualizing a clade can help you understand how different species are related through evolution. When drawing a phylogenetic tree, a clade usually branches out from a single point representing the common ancestor.

Phylogenetic Tree

When attempting to understand the complexity of life on Earth, scientists often use a phylogenetic tree. This tree is a diagram that shows the evolutionary pathways and connections among different species or groups.

• Branches of the tree represent different lineages that have evolved over time.
• The tips of the branches typically represent the different present-day species.
• Internal nodes where branches meet often represent common ancestors shared by the descendent species.

A phylogenetic tree helps scientists hypothesize about the evolutionary history and relationships between species. It's important to realize that while a phylogenetic tree displays relationships, not every branch represents a monophyletic group; only clades do.

Shared Derived Trait

A shared derived trait is a unique characteristic that is specific to a particular group of organisms. This trait helps distinguish the group from others.

• Such traits arise as new traits in a lineage and are shared among all descendants of that lineage.
• They are central to the classification and identification of clades because they point to common ancestry.
• Examples can include unique traits like the presence of feathers in birds or the ability to produce milk in mammals.

By studying shared derived traits, scientists can map out the traits that have evolved and use them to understand evolutionary relationships.

Character State

Character states refer to the different forms that a particular trait can take among various organisms in a group. They help scientists identify evolutionary changes and construct phylogenetic trees.

• Character states vary among species; for example, eye color among animals or leaf shape among plants.
• Understanding the changes in character states can provide insight into how species have adapted over time.
• They are used to compare species and can indicate evolutionary divergence.

By examining character states, researchers can better understand how traits have evolved within lineages and thus understand the history and evolution of the taxa in the tree of life.