Topic 4 Flashcards
What is systematics?
The theory (and practice) of classifying organisms based on evolutionary history
What term describes the evolutionary history of a species or group of related species?
Phylogeny
What are phylogenetic trees?
Diagrams that show hypotheses of the evolutionary relationship between organisms
What is a taxa?
A set of organisms (or group of organisms)
What does a branch point represent in a phylogenetic tree?
Each branch point or node represents the divergence of two species (speciation)
Two descendants that split from the same node are called?
Sister taxa
What is a basal taxon?
An outgroup that diverges early in the history of a group and originates near the common ancestor of the group
A branch from which more than two groups emerge is a?
Polytomy
A group of taxa that includes an ancestor and all descendants of that ancestor is a?
Clade
What are the two types of phylogenetic trees?
Cladograms and phylograms
What is a cladogram?
They depict evolutionary relationships where only branch order is important
What is a phylogram?
They depict evolutionary patterns but branch lengths are proportional to evolutionary change
T/F: The order of terminal taxa matters in the relatedness of taxa
False
T/F: Phylogenetic trees show evolutionary relationships, not evolutionary progress
True
What do phylogenetic polytomies indicate?
Lack of knowledge and rapid speciation
What is an ingroup?
The group of taxa whose relationships you are interested in determining
What do you call anatomical, physiological, or molecular features that make up organisms? What is an example of one?
Characters
Ex. DNA sequence
What is state?
The observed manifestation of a character
Ex. arrangement of petals
T/F: Characters that are similar because of descent from a common ancestor are said to be analogous
False
Homologous
Similarities due to independent adaptation by different species are said to be:
Analogous
Convergent evolution is?
Analogous character states appear the same but actually evolved independently
How does convergent evolution occur?
Occurs when similar environmental pressures and natural selection produces similar adaptations in organisms from different evolutionary lineages
Analogous structures or molecular sequences that evolved independently are called:
Homoplasies
What is the method of inferring phylogeny from homologous characters?
Cladistics
A valid clade is _ if it consists of an ancestor taxa and all its descendants and no other unrelated taxa
Monophyletic
A _ grouping consists of an ancestral taxon, but not all of the descendants
Paraphyletic
A _ grouping includes distantly related taxa but does not include the common ancestor of all group members
Polyphyletic
Choosing the phylogeny that requires the fewest number of evolutionary events is called:
Parsimony (Occam’s Razor)
Another word for a shared derived character is:
Synapomorphy
Another word for a shared ancestral character is:
Symplesiomorphy
