20 Questions
Which group is considered a monophyletic group (clade)?
Group I
Which group is considered a paraphyletic group?
Group II
Which group is considered a polyphyletic group?
Group III
What is the definition of a monophyletic group (clade)?
A group consisting of an ancestral species and all of its descendants
What is the definition of a paraphyletic group?
A group consisting of an ancestral species and some of its descendants
What is the definition of a polyphyletic group?
A group consisting of species from different lineages
Which group does not include all the descendants of the common ancestor?
Group II
Which group includes the most recent common ancestor of its members?
Group III
Which group consists of species that share similar characteristics?
Group IV
Which group consists of an ancestral species and all of its descendants?
Group I
Which of the following is an example of a shared ancestral character?
Backbone in vertebrates
Which of the following is an example of a shared derived character?
Backbone in mammals
What is the term for the group of species being studied?
Ingroup
What is the term for a species or group of species closely related to but not part of the ingroup?
Outgroup
Why is the group of even-toed ungulates considered polyphyletic?
Because it does not include the most recent common ancestor of its members
What can help to infer evolutionary relationships?
Both shared ancestral and shared derived characters
Which of the following is an example of a shared derived character in the context of the entire animal kingdom?
Backbone in vertebrates
Which of the following is an example of a shared ancestral character in the context of the group including mammals?
Backbone in mammals
What is the term for the evolutionary novelty unique to a particular clade?
Clade
What can branch lengths in a phylogenetic tree indicate?
The time of appearance of shared derived characters
Study Notes
Phylogenetic Groups
- A monophyletic group (clade) is a group that includes an ancestral species and all of its descendants.
- A paraphyletic group is a group that does not include all the descendants of the common ancestor.
- A polyphyletic group is a group that consists of species that share similar characteristics, but do not share a recent common ancestor.
Definitions
- A monophyletic group (clade) is a group that includes all descendants of a single common ancestor.
- A paraphyletic group is a group that excludes some, but not all, descendants of a single common ancestor.
- A polyphyletic group is a group that includes species that do not share a recent common ancestor, but are grouped together based on shared characteristics.
Characteristics of Phylogenetic Groups
- A monophyletic group includes the most recent common ancestor of its members.
- A paraphyletic group does not include all the descendants of the common ancestor.
- A polyphyletic group consists of species that share similar characteristics, but do not share a recent common ancestor.
Types of Characters
- A shared ancestral character is a characteristic present in an ancestral species and inherited by its descendants.
- A shared derived character is a characteristic that has evolved in a particular group of organisms and is present in all members of that group.
Terminology
- The group of species being studied is called the ingroup.
- A species or group of species closely related to but not part of the ingroup is called the outgroup.
Examples
- The group of even-toed ungulates is considered polyphyletic because it includes species that do not share a recent common ancestor, but are grouped together based on shared characteristics.
- Molecular or morphological data can help to infer evolutionary relationships.
- The presence of hair is an example of a shared derived character in the context of the entire animal kingdom.
- The presence of mammary glands is an example of a shared ancestral character in the context of the group including mammals.
- An autapomorphy is the term for an evolutionary novelty unique to a particular clade.
- Branch lengths in a phylogenetic tree can indicate the amount of evolutionary change that has occurred in a particular group.
Test your knowledge of cladistics with this quiz! Learn about monophyletic, paraphyletic, and polyphyletic groups and how they are classified in evolutionary biology. Can you identify the correct classification for the given species? Find out now!
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