Quest 2 Flashcards
Phylogenetic Systematics
Organizing life based off Evolutionary history
Willi Hennig
Phylogeny
Branching relationships of populations as they give rise to multiple descendant populations over evolutionary time
Characters
Any observable characteristic
What can be used as a character?
A trait or feature of an organism that provides useful information about its evolutionary relationships with other organisms
Character state/trait
Morphology, anatomy, behavior, molecular data
What are the two traits can give us?
1) The observations of traits can infer patterns of ancestry and descent
2) Traits can be mapped to infer evolutionary events
What are the two hypotheses you can ask with phylogenetics?
1) Relationships and pattern of evolutionary processes
2) Phylogenetics allows us to test past hypotheses
Node of phylogenetic tree
Common ancestor
What are branches on phylogenetic trees?
Descendants
What is a root on a phylogenetic tree?
Common ancestor to the whole tree, link to rest of life
Outgroup
Group related but diverged earlier
Sister taxa
Taxa from the same node
Monophyletic group
Common ancestor and all descendants
Polytomy
Node with more than two branches
Clade
Group of organisms that share a common ancestor
Carolus Linnaeus
Binomial nomenclature
Monophyletic group
A taxonomic group consisting of all descendants of the groups most recent common ancestor and no others
Paraphyletic group
A group of organisms descended from a common evolutionary ancestor or ancestral group, but not including all the descendant groups
Cladogram
Has the branch tips aligned and indicates only the evolutionary relationships among the species shown
Shows least amount of info
Phylogram
Indicates evolutionary relationships and also represents the amount of sequence change along each branch by means of differing horizontal branch lengths.
Chronogram
Showing actual time at divergence
Homologous trait
Shared by two or more species because they inherited this trait from a common ancestor
Analogous
Due to convergent evolution
Homology
Similarity of the structure, physiology, or development of different species of organisms based upon their descent from a common evolutionary ancestor
Analogy
Similarity of function and superficial resemblance of structures that have different origins
Divergent Evolution
Represents the evolutionary pattern in which species sharing a common ancestry become more distinct due to differential selection pressure which gradually leads to speciation over an evolutionary time period
Convergent Evolution
When two or more unrelated species independently evolve similar traits or adaptations due to similar environmental pressures, resulting in analogous structures that serve similar functions despite not sharing a recent common ancestor
Morphological data
Observable physical characteristics of an organism
Common Ancestor
Ancestral group of organisms that is shared by multiple lineages
Synapomorphy
When a derived trait is shared because of a pattern of common ancestry
Derived trait
When a trait has evolved from another trait
Homoplasy
A trait that is shared by two or more species because t has been inherited from a common ancestor.
Symplesiomorphy
An ancestral shared trait that confuses actual relationships
Why are there vestigial Organs?
1) Not selected against, not causing harm
2) Some NS against, but weak and it is slow to be removed
3)The trait has a function we have not found
4) Trait disadvantageous but no ready path for NS to remove
5) Trait linked to second trait that is being selected for
What do you need to make a phylogenetic tree?
Some taxa, characters, method
Parsimony
The best phylogeny is the one that explains the observed character data and posits the fewest evolutionary changes
Rooting the Phylogeny
Helps us with polarity and tells us if a character is ancestral or derived
Phylogeography
How a group of populations or species moved across the globe over the course of their evolutionary history
Phylogenetic Distance Methods
One way to measure molecular distance between species is to count the number of differences
Maximum likelihood
Statistical method before phylogenetic search criterion
Give a model of evolution and ask how likely am I to get this model
Method for creating a phylogenetic tree
Bayesian Inferences
Employs MCMC stats, which tree is most probable
Method for creating a phylogenetic tree
Bootstrap resampling
Resampling of the original data set by picking traits one at a tie from the original data.
100% is good when on a tree.
microevolutionary processes
migration and dispersal
Macroevolutionary processes
radiations and speciation
Independent Contrasts
Do not compare all organisms equally, rather look at evolutionary clades, compare between those with a shared evolutionary history.
