Classification & cladistics - cladistics Flashcards
What is the basis for the modern classification of organisms?
DNA sequencing technology
This technology allows classification based on evolutionary relationships.
What is a clade?
A group of organisms that share a recent common ancestor
Clades are monophyletic groups that include all descendants of a common ancestor.
What does it mean for a clade to be monophyletic?
It contains all descendants of a common ancestor
This ensures that the group reflects true evolutionary relationships.
What is cladistics?
The branch of science that classifies organisms into clades
Cladistics focuses on identifying evolutionary relationships.
What is a taxon?
A group of organisms given a name based on shared features
Taxa can be formal groupings based on taxonomy.
What is the primary method for grouping species into clades?
Using sequence data from DNA, mRNA, or amino acids
The similarity of sequences indicates evolutionary closeness.
True or False: Morphological characteristics are always reliable for determining evolutionary relationships.
False
Similar morphology can result from convergent evolution rather than recent common ancestry.
What are primitive traits?
Traits that evolve early in the lineage of a clade and are found in all members
Examples include spinal cords in vertebrates.
What are derived traits?
Traits that evolve later and can differ between clade members
For example, feathers in birds versus fur in mammals.
What is the molecular clock?
A method to estimate the time since species diverged based on mutation rates
It assumes a constant mutation rate over time.
How is a cladogram constructed?
Using sequence data to show probable order of divergence
Cladograms visually represent evolutionary relationships.
What does a node in a cladogram represent?
A common ancestor species
Nodes indicate points of divergence in evolutionary history.
What does the principle of parsimony state?
The simplest explanation is preferred
This principle guides the construction of cladograms.
What information can be inferred from analyzing a cladogram?
Relationships between clades and their common ancestors
Nodes and branch lengths provide insights into evolutionary history.
What are the terminal branches in a cladogram?
They represent the most recent species in an evolutionary lineage
Terminal branches indicate current organisms derived from ancestral lines.
Fill in the blank: Cladograms based on the sequencing of _______ will be less reliable than those based on several genes.
one gene
More sequence data increases reliability.
What can affect the rate at which mutations accumulate?
Generation time, population size, selection pressures
These factors can influence the molecular clock accuracy.
