Taxonomy and phylogeny Flashcards
Taxonomy
Science of classification and naming organisms
Binomial nomenclature
Naming organisms
Hierachy
Classifying organisms into groups
Binomial nomenclature
Species has a unique name, two of them, the genus name and specific species epithet
Scientific name
Genus name and specific species epithet
Why we use scientific name
Clearer communication between different researchers, prevents confusion that comes with using common name
Scientific name
Italicized when printed and underlined when handwritten, genus in capital letters, specific species epithet lowercase
Taxonomic hierarchy
Did king Phillip come over for good sex
Systematics
Classifies organisms and determines their evolutionary relationships
Domains
I) arches
II) bacteria
III) eukarya
Kingdoms
I)Animalia
II) planetae
III) fungi
Phylogeny
Is the evolutionary history of organisms
Goal of systematics
Is to generate an evolutionary tree or phylogeny that relates all living and extinct species
Taxon
Organisms or group of organisms. Plural taxa
Terminal taxa
At side of branches, can be extinct or living, have no descendants on the tree
Sister taxa
Most likely related to each other than any other taxon
Basal taxon
Evolved first, found at base. Selected purposefully to be an organisms less closely related to other members of the tree to root the tree.
Polytomy
Unknown pattern of divergence
Analogy
Similarity due to convergent evolution
Use of phylogeny
I) can provide information about similar characteristics in closely related species
II)can be used to trace viral evolution, antibiotic resistance,etc.
Homology
Similarly due to shared ancestor
How are phylogenies constructed
I) systematists need to distinguish if similarly is due to analogy or homology
Homoplasies
Analogous structures that evolved independently
Cladistics or phylogenetic systematics
Grouping of organism based on common descent
Cladistics
Systematic process that groups organisms by common descent
Monophyletic
Valid Clade, includes ancestral species and all of its descendants
Clade
Is a group of species that includes ancestral species and all its descendants
Paraphyletic
Non Clade group, has clade and only some of its descendants
Polyphyletic
Do not share a common ancestor included in the grouping
Shared derived character
Evolutionary novelty unique to a particular Clade
Clade names are found
Labels next to branching points
Shared ancestral character
Originated in an ancestor of the taxon
Outgroup
Species or group of species close to the ingroup
Unique derived character
Only found in one taxon
Characters shared by ingroup and outgroup
Ancestral characteristics
Derived characters
Found in the ingroup and absent in the outgroup
Branch lengths can tell
Genetic change or chronological time
How to tell if phylogeny is right
Maximum parsimony and maximum likelihood
Maximum parsimony
Based on occam razor, it assumes that the tree that requires the fewest evolutionary events is the most likely.
Occam razor
Principle that of two explanations that accounts all the facts the simpler explanation is more likely to be correct
Maximum likelihood
Given certain rules about how DNA changes over time, a tree can be found that reflects the most likely sequence of evolutionary events.
Best trees
Supported by maximum parsimony and maximum likelihood
Best hypothesis for phylogenetic trees fit the most Data
Morphological, fossil and molecular
Clade
A group of species that includes an ancestral species and all of its descendants
