Phylogeny and Cladistics Flashcards
What is phylogenetics?
The study of evolutionary relationships between organisms
The study of phylogenies
hypotheses about how the species got to where they are
What are phylogenies?
Evolutionary histories of species or lineages(how species got to where they are now)
what are the lines of evidence used to make hypotheses for phylogenetics?
Homologous morphology (shape form (bone arrangement between species)
The fossil record
Behaviour and habitat
Molecular sequences (protein or DNA sequences)
Phylogenetic trees
A branching diagram that represents a hypothesis about the evolutionary history of a group of organisms
can be drawn to show relationships
between closely related species
can be drawn to show “all” known species
allow us to classify organisms into different hierarchical groups
Domain
taxonomic category above level of kingdoms
Kingdom
taxonomic category above level of phylum
Phylum
taxonomic category above level of classes
Class
taxonomic category above level of order
Order
taxonomic category above level of family
Family
taxonomic category above level of genus
Genus
taxonomic category above the species level- to which the species belongs to (plural is genra)
Species
a population or group of populations whose members have the potential to interbred in nature and produce viable fertile offspring but not produce viable fertile offspring with members of other such groups
Taxon/taxa
a named taxonomic unit at any given level of classification
Basal taxon
in a specified group of organisms, a taxon whose evolutionary lineage diverged early in the history of the group
Sister taxa
group of organisms that share an immediate common ancestor and are each others closest relative
Outgroup
A species or a group of species from an evolutionary lineage that is known to have diverged before the lineage that contains the group of species being studied
is selected so that its members are closely related to the group of species being studied but not as closely related as any study group members are to each other
Clade
a group of species that includes an ancestral species and all of its descendants
Grade
a group of organisms that share the same level or organization complexity or share a key adaptation
Monophyletic
a group of taxa that consists of a common ancestor and all of its descendants
(Any species by itself is monophyletic, Taxon is equivalent to clade)
Paraphyletic
a group of taxa
that consists of a common ancestor and some but not all of its descendants
Polyphyletic
a group of taxa
which includes distantly related species but not their most recent common ancestor
Ancestral character
a character shared by members of a particular clade that originated in an ancestor that is not a member of that clade
Derived character
an evolutionary novelty unique to a clade
traits are only found in clade in question
Arrange the taxa in their proper Linnaean hierarchy
species genus family order class phylum kingdom domain life
Branch point
(internal node) represents common ancestor of the 2 evolutionary lineages
Taxonomy
a scientific discipline concerned with naming and classifying the diverse life forms
Cladistics
organisms are placed into groups called clade based primarily on common descent
Ingroup
species or group of species whose evolutionary relationships we seek to determine
Cladogram
a branching diagram that is used to show phylogenetic relationships among organisms
Phylogram
a phylogenetic tree wherein the branch lengths are proportional to the amount of change seen in species characteristics
Usually display time or molecular difference
What is the best evidence to male a phylogenetic tree?
molecular sequences because they show concrete differences
homologies
Phenotypic and genetic similarities due to shared ancestry
Binomial
the two-part Latin format of the scientific name of a species
How is the binomial arranged?
1st part is genus
2nd part is the specific epithet
How did Linnaeus group species?
grouped species into a hierarchy of increasingly inclusive categories
Species that are appeared to be closely related are grouped into the same genus
Principle of maximum parsimony
1st investigate the simplest explanation that is consistent with the facts (occams razor- the simplest solution is the best/correct one)
Principal of Maximum likelihood
a principal that states that when considering multiple phylogenetic hypotheses one should take into account the hypothesis that reflects the most likely sequence of evolutionary events given certain rules about how DNA changes over time
Do branch lengths matter in a cladogram?
Branch lengths don’t matter
Only branching order is important
Usually all drawn same length branches
Chronology represented by branching pattern is important- earlier vs later
What is the issue with the tree of life?
issue is prokaryotes include bacteria and archaea but this is problematic because in this current hypothesis the group prokaryote is not a monophyletic group so it couldn’t have just evolved just this way it must have had to evolve 2 groups that look similar that were both prokaryotes.(prokaryote is a descriptive term not a ture clade.
Some scientists argue there’s 2 domains bacteria and everything else but this is still problematic because the same problem explained above applies here to