Lecture 12 - Phylogenetic Systematics Flashcards
What is phylogeny?
the evolutionary history of a species or groups of related species
What is taxonomy?
the science of naming and classifying organisms
What is systematics?
scientific system for classifying organsims
What are phylogenetic systematics?
classification of organisms by their order of branching on an evolutionary tree
Who developed old-school taxonomy?
Carolus Linnaeus
What are the two parts for scientific naming?
- binomial nomenclature
2. hierarchical classification system
What has been added to the two part naming system?
Domain
What are the 7 levels of the hierarchical classification system?
(domain) kingdom phylum class order family genus species Do Kids Playing Catch On the Freeway Get Smashed
Why have old-school Linnaean categories been criticized?
do not always form monophyletic groups
The class Reptilia is _______
paraphyletic
Invertebrates are ____
paraphyletic
Homeotherms are ________
polyphyletic
What is PhyloCode?
-proposed classification system
How does PhyloCode work?
- only monophyletic groups would be recognized
- most species names would remain unchanged
- use traditional taxonomic ranks
What is a node?
where the lineages diverge
What are sister taxa?
- most closely related groups
- groups of organisms that share an immediate common ancestor
What is the basal taxon?
one that branches off the earliest
What is polytomy?
an unresolved point of divergence
What are branches rotated around?
nodes
Phylogenies are inferred form ______ not _________
homologous characters not analogous characters
What are homologous characters?
common ancestors
What are analogous characters?
similar selective environments
What are homoplasies?
analogous structures or molecular sequences that evolved interdependenty
What is cladistics?
one approach to reconstructing phylogeny
Cladistics groups species into ______
clades
What are clades?
ancestor and all its descendents
What does cladistics focus on?
shared, derived characters
What principles does cladistics use?
- parsimony
2. maximum likelihood
What is outgroup comparison?
distinguishes between ancestral and derived characters
What is an outgroup?
species/group from an evolutionary lineage that is known to have diverged before the lineage that includes the species we are studying
What happens in maximum parsimony?
the best tree requires the fewest changes
What is maximum likelihood?
alternative approach to reconstructing phylogeny
What happens in maximum likelihood?
the best tree is the tree with the highest likelihood given certain rules about how DNA changes over time
-more computationally intensive
What is a monophyletic group?
a common ancestor and all its descendents
What is a paraphyletic group?
a common ancestor and some of its descendants
What is a polyphyletic group?
a common ancestor is not present, but some descendants are
What is an example of real-world parsimony?
four chambered hearts in birds/mammals
