LAB 1 Flashcards
Phylogeny & Cladistics
What is a phylogeny?
A group’s evolutionary histroy depicted in a branch/tree like form
What is a taxon?
Each branch of a phylogenetic tree is a taxon
Could be individual specieis or any other group of closly related organisms in a genus or family
What is represented by numbers and is a node/fork in a phylogenetic tree?
The common ancestor for all taxa past it
What is the first group to diverge from the oldest common ancestor called?
The Basal taxon
What are sister taxa?
The two groups that descend from the sam common ancestor
How do you read the phylogenetic trees?
Through the nodes/common ancestors
NOT THE BRANCES
What is a polytomy?
When there are many branches from the same node
What is the systematics approach known as cladistics mean?
Taking the common ancestry as the major criterion to be used
What is a clade?
A branch of a tree, fromn the node to the ends of the subsequent branches, representing a common ancestor and all of its decendants
What is am monophyletic clade?
When the clade contains and entire branch of a phylogeny (one tree)
What is a paraphyletic tree?
Some of the decendants from the common ancestor, but not all
What is a polyphyletic tree?
Studying the branches of many clades
What are the 3 types of traits we group species into clades over?
- Morphological
- Developmental
- Molecular
What is the difference between an ancestral and derived shared characteristic?
- Shared Ancestral: the characteristic is shared by the clade an dits ancestors
- Shared Derived: the characteristic is shared only by eachother and not the ancestor
How do you determine if a shared characteristic is ancestral or derived?
You compare the group in question to a closly related group called the Outgroup
- Best outgroup is not part of the clade in question but its closest relative
- If the outgroup has it, its shared ancestral, if not, shared derived
What are the ticks on a phylogenetic tree?
The defining characteristic of the taxon/clade
