Week 11 Flashcards
(24 cards)
What does a phylogenetic tree represent?
Shows the evolutionary pathways and connections among organisms
A phylogenetic tree is a hypothesis about when organisms evolved and their relationships.
What is the difference between rooted and unrooted trees?
Rooted trees show a common ancestor; unrooted trees show relationships among species without a common ancestor
Rooted trees include a single ancestral lineage for all organisms represented.
Define ‘taxon’.
Group(s) of organisms (species, family, domain, etc.)
What is a clade?
Any branch or lineage in a phylogenetic tree
What does a branch point (node) represent?
A splitting that represents a single lineage evolving into two clades
What is a basal taxon?
Lineage that evolved early and remains unbranched
What are sister taxa?
Taxa that stem from the same recent branch point
What is a polytomy?
A branch with more than two lineages indicating uncertainty
List some methods used to reconstruct phylogenetic trees.
- Fossil records
- Morphology
- Physiology
- Behavior
- Embryological development
- DNA/RNA sequences
True or False: The length of a branch in a phylogenetic tree indicates the amount of time passed since the split.
False
What is taxonomy?
Science of classifying organisms into taxa
What is a shared homologous structure?
Inherited (with modification) from a common ancestor
Define analogous structures.
Appear similar but were not inherited from a common ancestor
What is convergent evolution?
Structures evolving from similar evolutionary pressures but not from a common ancestor
What does ‘descent with modification’ refer to?
Organisms evolve from common ancestors and diversify
What is a monophyletic group?
Includes all descendants of a given ancestor, including the most recent common ancestor
What is a synapomorphy?
A shared, derived trait
Fill in the blank: The rule of _______ states to choose the simplest cladogram with the fewest steps or events.
parsimony
What has changed in the perspective on phylogenetic trees since Darwin’s time?
New technologies have shown that fungi are more closely related to animals than to plants
What is an example of evolutionary reversal?
Loss of limbs in snakes
What do shared ancestral characters indicate?
Found in the common ancestor of taxa, and all members of the clade have it
True or False: Evolution leads to perfection.
False
What is the significance of the evolutionary history in constructing cladograms?
It helps in determining the relationships among different taxa
What is the defining characteristic of homologous characters?
Similar due to evolutionary origin
