PHYLOGENIES

Lecture 22

Sequentical Speciation

When a new species evolves from a most recently formed species

Great Tree of Life

Idea proposed by Darwain stating all life forms are connected to one common ancestor : however in this tree evoltion occurs at different rates

Systematics 

Branch of biology that studies the evoluntionary hierachy relationship between groups; classification should be done on evoltionary relationships between taxa

Linnean Hierachy 

Classifys organsim into groups based on shared charateristics; hierachy exist between organism however the ranks we put these organism in is a human construt 

Homology vs Analogy

similarity between species due to sharing a common ancestor; similarity between species because of convergent evolution

Grade vs Clade

grade involves grouping organisms based similar characteristics( level of evolution) grouping organisms that descended from a common ancestor; best to build trees on clades

Phentic

Method used to measure an phylogenetic tree by considering the overall similarity between observable traits ; collect as many characters as possible to quantify simliarity to create pair-wise distances between taxon ( morphological distance matrix )

Divergence

Aligin sequences between groups to determine its length, and count the difference present ; # of difference/length of sequence

Distance Matrix

The % of divergence at different DNA postions between species ( calculates from all pairwise distances )

Neighbor Joining Method

Builds unrooted trees based on pairwise distances of divergence in DNA

Cladistic Method

Classfiying organisms based on shared-derivied charteristics ; must collect the charaters and charater states of organism to create a charater state martix to cluster organism according based on their shared charaters

Character vs. Character States

Trait; Alternative Forms of Trait

Uniformative vs Informative vs Conflicting Charaters

invariant shared between two taxa;clustering that conflict clustering of other characters 

Consientacy Index

the # of character states in data set/# of steps in a tree ( we want our tree to have the fewest amount of steps possible to be parasiomous )

Bootstrap Method

A statical method used to estimate different branching postions to find the most accurate pairing; uses a sythetic dataset by resampling different postions to find if its supports our observed branching