Lecture 25 & 26: Systematics Flashcards
What is the goal of systematics?
to identify and classify taxa as well as determine the evolutionary relationships of taxa
What is Linnean hierarchy?
KPCOFGS, but there are some problem with classification
Define homology
similarity in form due to descent from a common ancestor
Define analogy
similarity in form despite different ancestry; convergent evolution
Define grade
Grade = level of adaptation; organisms of similar grade due to similar adaptations due to convergence (e.g., the “dog” grade or the “anteater” grade that goes across marsupial/placental distinction)
Define clade
a group descended from one common ancestor; a genetic lineage (e.g., the placental clade vs. the marsupial clade).
Define sister taxa
two lineages that descend from a common ancestor following a splitting event
Define monophyly
a group consisted off all descents of a single common ancestor
Define polyphyly
more than one common ancestor
Define paraphyly
a “group” not containing all descendants of a single common ancestor
Understand the phenetic (distance) method of reconstructing a phylogenetic tree.
- Collect as many characters as possible
- Construct pair-wide distance between each taxon in your study
- Cluster taxa based on overall similarity
- Assume homology outweighs analogy.
Understand the cladistic method of reconstructing a phylogenetic tree,
- Collect characters and characters states
- Build a character matrix
- Cluster organisms according to patterns of shared-derived characters
- Use parsimony to determine best tree
Define synapomorphy
A shared, derived trait.
What is a character?
a trait
What is a character state?
alternative forms of a trait
