Exam #3 - Phylogenetic Trees Vocab Flashcards
(23 cards)
Taxon
Any name group of organisms, such as a population or species
Root
Most ancestral population in a phylogenetic tree - where the tree originates
Branches
Represents populations through time
Nodes
Occurs where a hypothetical ancestral group splits into two or more descendant groups
Tips
The tree’s end points
- each name on a tip represents a taxon of organisms living today oe in the past
Monophyletic Group
Consists of an ancestral species and all of its descendants
Trait
Indicated by a black bar; can be ancestral or derived
- Ancestral trait: a characteristic that existed in an ancestor
- Derived trait: a characteristic that is a modified form of the ancestral trait, found in a descendant
- Synapomorphy: a shared, derived trait; occurs in all the branches to the right of the black bar; a trait can be a characteristic that is gained or that is lost
Outgroup
A taxon that is known to have diverged before the rest of the taxa shown in the tree
Microevaluation
Evolution observed at the population level
Macroevolution
Evolution observed at the species level
Phylogeny
The branching evolutionary history of species or other groups of organisms
Phylogenetic Tree
A simplified diagram of this history
Systematics
The discipline of biology that characterizes and classifies the relationships among all organisms on Earth
Polytomy
A node that depicts an ancestral branch dividing into three or more descendant branches
Sister Groups
Two descendants that split from the same node and therefore are each other’s
Trait Cont.
Any heritable genetic, morphological, physiological, developmental, or behavioral characteristic that varies among the taxa to be studied
Synapomorphy
A trait found in two or more taxa that is present in their most common ancestor, but is missing in more distant ancestors
- Include origin of novel characteristics
- Allow biologists to recognize monophyletic groups - also known as clades or lineages
Homology
Similarity due to common ancestry
Homoplasy
Occurs when traits evolved independently in two or more different lineages
Parsimony
Assumes that the most likely explanation or pattern is the one that requires the fewest steps
Evolutionary Distance
Acknowledges that more rapid evolutionary change may occur in some branches than others
Convergent Evolution
The independent evolution of similar traits in distantly related organisms due to adaptation to similar environments and lifestyles
Evidence That Supports Homology
- Phylogenetic evidence
- Structural evidence
- Genetic & developmental evidence
