Lecture 18: Speciation I: Phylogenies

Phylogenetic Tree

A graphical depiction of the evolutionary relationships among taxa 

Taxa

a singular taxon on the the phylogenetic tree

Clades

groupings of taxa

What indicates how closely related two taxa are

then distance back to the most recent common ancestor

What is the end of a phylogenetic tree?

Latest Common ancestor

How do you show speciation on a phylogenetic tree?

creation of a branch

How do you show extinction on a phylogenetic tree?

end of a branch

What does a node mean?

Last common ancestor

C. Equally related to A or B

A,B,D

A. Yes

Why does relatedness matter?

Two species more closely related= more similar phenotypes

Monophyletic Clades

a group that includes ALL taxa descended from a specific common ancestor

D

Why do Monophyletic Clades matter?

They show if a trait arose at a single point in the past

Homologous Trait

a trait that is similar in different organisms because inherited from a common ancestor

Analogous Traits

A triat that is similar in different organisms because of similar selective pressure

Convergent Evolution

Produces analogous triats

Analogous

Analogous