Phylogenetic Trees (11.2) Flashcards
Describe phylogenetic trees
Diagram representing evolutionary relationships between species.
State what 2 things a phylogenetic tree can be
- Rooted
2. Unrooted
Compare and contrast a rooted and unrooted phylogenetic tree
Rooted trees - ancestral relationships
Unrooted trees - show relatedness between species
State 2 alternative terms used to describe phylogenetic trees
Evolutionary trees/phylogenies
State what 2 types of homologous features can be used in the construction of phylogenetic trees
- Morphological
2. Molecular
Outline the aim of phylogenetic trees
Reveal branching history of common ancestry
State what 2 pieces of information scientists can use to reconstruct the evolutionary past of species
- Morphological evidence
2. DNA or RNA sequences
State what most phylogenetic trees are constructed on the basis of today
DNA or RNA sequence data
State what phylogenetic trees based on molecular characters can be used to compare
Any organisms (even if they seem to have very few characteristics in common)
State what must be taken into account when constructing phylogenies
Varying mutation rates of different DNA or RNA regions
State what phylogenetic trees are usually constructed using
Sequence alignments of same gene
Describe phylogeny
Evolutionary history of lineages as they diverge from a common ancestor over time
Describe Linnaean system of classification
A hierarchical system of classifying organisms
State how organisms are organised into a hierarchy of groups based on the Linnaean system of classification
Taxa
Describe taxon
A group of organisms that form an evolutionary unit
State what Biologists describe taxa based on
The Linnaean system of classification
State what the science of classifying organisms based on their shared characteristics and evolutionary history is termed
Taxonomy
State the 9 levels of classification from broadest to most specific
- Domain
- Kingdom
- Phylum
- Sub-phylum
- Class
- Order
- Family
- Genus
- Species
The greater the number of nucleotide differences between sequences or taxa, the greater…
The distance between them
Describe lineage
All the species that are descendants of a common ancestor
Describe an outgroup
More distantly related group of organisms compared to ingroup to determine evolutionary relationships
Describe root
Represents the common ancestor of all taxa present in the tree
Describe from where branches and leaves extend in a phylogenetic tree
Root or ancestral lineage
State what each line on the tree is termed
Branch
State what a branch represents
The evolutionary path from the common ancestor
State what the end of each branch contains
A scientific name
State what the end of each branch on a phylogenetic tree is termed
Leaf
State what the point at which two branches diverge
Node
State an alternative term to describe the point at which two branches diverge
Branch point
State what the node or branch point represents
Last common ancestor that the diverging groups shared
State what the outgroup species is sometimes included in a tree diagram for
Compare evolutionary relationships of ingroup
State what pairs of taxa grouped together are termed
Sister taxa
State what sister taxa are
The most closely related relative to other taxa in the tree
State what the most closely related taxa have between them
The shortest branch lengths
State what each section of a phylogenetic tree is termed
Clade
Describe clade
A group of organisms that include an ancestor and all the descendants of that ancestor
State what shorted branch lengths in phylogenetic trees indicate
That there have been fewer evolutionary divergence points between the taxa and they are therefore less divergent
State what the order in which clades diverged from their common ancestor are represented by
The order of the branching points (or nodes)
State the 3 different ways in which taxa can be grouped
- Monophyletic groups
- Paraphyletic groups
- Polyphyletic groups
Describe monophyletic groups
Groups that include a common ancestor and clade
Describe paraphyletic groups
Groups that include a common ancestor and some of its’ descendants
Describe polyphyletic groups
Groups that include multiple descendants but do not include a common ancestor
State the 2 further classifications of unrooted and rooted trees
- Scaled
2. Unscaled
State a term to describe scaled trees
Phylograms
State a term to describe unscaled trees
Cladograms
State what the order of branching points from root to tip represent
The order of evolutionary divergence of taxa
State what the root of a tree represents
Hypothesised common ancestor of all the taxa in the tree
State what the time that has passed since the organisms shared a common ancestor can be represented by
Branch length
State what the outgroup defined during the analysis of root formation provides
A comparison point
Describe ingroup
Main group of organisms
State what the lengths of branches connecting two organisms indicates in phylograms
The amount of genetic divergence between them
Describe polytomies
A node in a phylogenetic tree that indicates three or more lineages evolving from a common ancestor
State what unrooted trees do not include
An ancestral root
State what unrooted phylogenetic trees often have
Radial layout
State why unrooted phylogenetic trees often have a radial layout
Because the ancestor is not defined in unrooted trees
State when polytomies occur
When there is not enough information to distinguish the order of evolution or when rapid speciation has occured after adaptive radiation in a new environment
State what lineages will be closely related after rapid speciation has occured
Daughter lineages
State what unrooted phylogenetic trees only indicate
The relationship between different leaf nodes
State what unrooted phylogenetic trees do not indicate
Which node is the most ancestral
State whether or not unrooted trees can have scaled branches
Yes
State whether or not rooted trees can have scaled branches
Yes
State the 3 domains
Archaea, Eukarya, Bacteria
State the 4 kingdoms
Protista, Animalia, Plantae, and Fungi
State the pneumonic used to remember break down of taxa
Dear King Philip Says Come Over For Good Soup
State why sequences of DNA and RNA must first be aligned before analysising the evolutionary relationships between species
Reduce effect posed by varying mutation rates of different DNA or RNA regions
State what a phylogenetic tree that is rooted and unscaled is termed
Cladogram
State what a phylogenetic tree that is rooted and scaled is termed
Phylogram
State what a phylogenetic tree that is unrooted and scaled is termed
Phylogram
State what a phylogenetic tree that is unrooted and unscaled is termed
Cladogram
State the 4 types of phylogenetic/evolutionary trees
- Rooted and unscaled
- Rooted and scaled
- Unrooted and unscaled
- Unrooted and scaled
State 2 pieces of evidence that can be used to construct phylogenetic trres
- Morphological comparison
2. DNA analysis comparison
