Lecture 2 - Taxonomy & Systematics (Part 2) Flashcards
What is Systematic?
The theory and a little practice of classifying organisms.
The “Why”
What are people called when they engage in Systematics?
Systematists
What do modern Systematists focus on?
They focus on the reason why particular taxa should be group together.
ie. The evolutionary reason why things should be grouped together.
What major change happened to systematics in 1960?
The focus was switched from simply adding new taxa to methods for determining relatedness among taxa.
Why did the old taxonomies need to be changed in the 1960’s?
They were changed out of the desire for evolutionary informative classifications
What was one of the major results of the taxonomies change in the 1960s?
Taxonomies in textbooks rapidly became out of date.
What is molecular systematics?
it is the use of molecular genetics to study the evolution of relationships among individuals and species
What has the rise of molecular systematics done to taxonomies?
It has accelerated the rate of change, due to the use of proteins. DNA, and RNA to better study the relationships of species.
What is the 5 kingdom classification?
Bacteria Protista Plantae Fungi Animalia
What is the modern “kingdom” classification?
It involves 10 kingdoms with a new taxonomic level, the domain.
What was systematics like before the 1960’s?
it was a Relatively unstructured discipline, although systematists wanted to create a evolutionary sensible classification
What is stratigraphy?
The temporal order in which fossils occur
What tools did systematists have before the 1960’s to classify species?
- Stratigraphy
- Expertise
- Primitive and advanced morphology
What is Primitive morphology?
Morphology based more off of guesses
What is advanced morphology?
Morphology based on facts, compared to other facts.
What was one of the major flaws with “old-style” systematics?
The methods were subjective, choosing witch classification was the best could be strongly influenced by personal preference.
What invention in the 1960’s allowed for a more objective classification of species within systematics
The computer.
Who invented Hennigs systematics? When?
German Entomologist Willi Hennig in the 1950’s
What drove the creation of the creation of the Hennigan systematics system?
The want for classifications that reflected ancestor-descendant relationships (or more generally shared evolutionary history)
When creating Hennigan systematics, what goal did Willi have in mind?
To create a method that was as objective, and transparent as possible.
What did Hennigan systematics argue the best way to determine evolutionary relationships was?
Focus on only the shared, derived characteristics.
What is a group of organisms that is related by shared and derived characteristics called?
A Calde
What was Hennig’s approach to determining evolutionary relationships called?
Cladistics or phylogentic systematics
What does Clados mean?
Branch
What does Phylon mean?
Tribe, or race
What does gen mean?
Create
What is a cladogram?
A branching diagaram that shows the hypothesized relationships between species.
What does gramm mean?
A mark or a line
What do Cladograms represent?
Only the order of evolutionary events (branching) and what taxa share most recent common ancestors.
What do the lengths of the branches on a cladogram mean?
Nothing at all
What is the root of a Cladeogram?
It is the base node, it represents the hypothetical common ancestror of all the Taxa on that tree.
What is a a branching point?
It is a part of the cladeogram where a branch diverge from its lineage.
What is a dichotomy?
A fully resolved split into two taxa.
What is a polytomy?
A node that is unresolved pattern of divergence.
Looks like a pitchfork
What are sister Taxa?`
two taxa on the same node.
What do the nodes further up the tree represent? (not the root)
They represent the more recent, and specific common ancestor.
What is a basal taxon?
A taxon that is directly attached to the root og the tree and has no further nodes.
TO construct a phylogentic hypothesis what information must systematists collect?
- Morphology
- Behavior
- DNA sequence
- Biochemistry
What is an Ingroup?
A group’s relationships a systematists is interested in untangling
What is a character?
Each type of structure, behavior, ect of a species.
What is a state?
The manifestation of a character in a given taxon
What is a out group?
a more distantly related group of organisms that serves as a reference group when determining the evolutionary relationships of the ingroup.
What does Sp. stand for?
Species singular
What does Spp. stand for?
Species Plural
Should Sp and Spp be italicized?
No
What is phyologeny?
refers to the evolutionary history of a taxonomic group of organisms
What is parsimony?
a set of nested relationships that minimizes the number of times a character has to change state.
What is Occam’s Razor/ Principle of Parsimony?
The best Hypothesis is one that requires the fewest postulations.
ie. the simplest answer is generally the correct answer.
What is a matrix?
Any grid with X and Y Rows.
When a outgroup state is set at “0” on a matrix what is the state concitered to be?
Ancestral/original
When a outgroup is set at “1” what is the state considered to be?
it is derived
What does “derived’ mean for an outgroup state?
It is a termed character-state polarization because the direction of change in the character is decided.
after you create a matrix what are you looking for? What is the goal?
Determine a set of nested relationships that minimizes the number of tines 0 changes to 1 / or 1 cnages to 0
Changes and relationships among taxa are often presented in what kind of diagram?
A Cladogram
What is a symplesiomorphy?
(cladistics) an ancestral trait shared by two or more taxa of a shared ancestry
What does plesio mean?
Near/similar to the ancestral state
What is a synapomorphiy?
(cladistics) a derived trait that is shared by two or more taxa of shared ancestry
What is a automorphy?
A unique derived character state present in only one taxon.
Is the presence of hair a synapomorpy of mammals amoung other vertebrates? what about within mammals?
It is a synapomorphy of mammals among other vertabrets
but it is symplesiomorphy within mammals.
relationships among taxa are interpereted from what?
from the order in which branches split, nit from how many names of taxa are arranged at the tips of branches.
true/false:
Trees cannot rotates at its nodes ( like a mobile) without altering the relationships.
False
Trees can rotates at its nodes ( like a mobile) without altering the relationships.
Cladistics works the best when all character states have the same what?
evolutionary origin, called homologous.
What does the root word “homo” mean?
same.
What is it called when character state appears the same but actually evolved independently
Analogus, homoplasious, or convergent.
molecular phylogenetics in today’s world focus mainly on what?
Matching base pairs in selected gene sequences.
The more matches there are in the DNA sequence the……
The more closely related they are likely to be.
What is a set of information that can be displayed through tree length in phylograms.
the number of differences between taxa.
Constant rate of mutation accumulated allows for what type of construction of trees?
Trees with branch lengths that may reflect time since divergence.
What is maximum Parsimony?
The tree that requires the fewest number of base pair changes
Within Molecular Taxonomy what is “maximum Likelihood”?
How DNA is most likely to change.
What does Monophyletic mean?
A true clade; one containing a common ancestor and all of its descendants and no other unrelated TAXA
What is the final goal for phylogenic classifications?
To reflect ancestor-descendant relationships by creating only momophyletic taxa.
What is it called when tAxa do not share recent ancestors and are limped together?
polyphyletic
What is a Paraphyletic group?
Groups that are formed that o not contain all descendants of a common ancestor
Hoe are Paraphylectic groups formed?
often form the the removal of taxa that are highly divergent fro the rest of the calde
