Cladistics Flashcards
What is a cladogram?
A diagram used in cladistics to represent the evolutionary relationships among a group of organisms
Cladograms illustrate the branching patterns of evolution.
Define cladistics.
A method used in biology to classify organisms based on their evolutionary relationships
It relies on the principle of common ancestry.
What is a clade?
A monophyletic group that includes a single ancestor and all of its descendants
Clades are fundamental units in cladistics.
Define monophyletic.
A single common ancestor and all of its descendants
Monophyletic groups are crucial for accurate classification.
What does paraphyletic mean?
A common ancestor and some of its descendants
Paraphyletic groups are not fully representative of all descendants.
Define polyphyletic.
A grouping with no recent common ancestor
Polyphyletic groups can misrepresent evolutionary relationships.
What do branches in a cladogram represent?
The lineages of different organisms being compared
The length of the branches does not represent time or evolutionary change.
What are nodes in a cladogram?
Points where branches intersect, representing a common ancestor shared by diverging organisms
Nodes are key to understanding evolutionary splits.
Define lineage.
Direct descent from an ancestor, especially a line of descendants from one ancestor
Lineages trace the evolutionary path of organisms.
What is an ingroup?
The group of living organisms whose relationships are being considered in a cladogram
The ingroup is the focus of the analysis.
Define outgroup.
A species or group closely related to the group being studied but not part of it
Outgroups help to root the cladogram.
What are ancestral traits (plesiomorphies)?
Characteristics shared by all organisms in the cladogram, including the common ancestor
These traits are not useful for determining relationships within the group.
What is an apomorphy?
A novel character or character state that has evolved from its ancestral form
Apomorphies are key for defining clades.
Define synapomorphy.
An apomorphy shared by two or more taxa, hypothesized to have evolved in their most recent common ancestor
Synapomorphies are important for grouping organisms.
What is an autapomorphy?
A distinctive feature, known as a derived trait, that is unique to a given taxon
Autapomorphies highlight uniqueness in a clade.
True or False: Cladograms indicate the amount of difference between groups.
False
Cladograms show relationships but do not measure differences.
What is the first step in constructing a cladogram?
Pick organisms for your cladogram
Choosing the right organisms is crucial for accurate representation.
What is the second step in cladogram construction?
Determine ancestral and derived traits
This step helps identify evolutionary relationships.
What is a data matrix in cladogram construction?
A matrix that organizes information about traits of the organisms
It facilitates the comparison of traits.
What is the role of the outgroup in a cladogram?
To provide a point of reference for the ingroup being studied
The outgroup helps establish the evolutionary context.
Fill in the blank: Cladograms are based on shared _____ characters.
derived
Derived characters help determine evolutionary relationships.
