Unit Two, Day 8 Cladograms

Opener Describe the Linnean system of classifying organisms. What does the term “phylogeny” mean? 1. 2. The evolutionary history of a species or group of related species

Dear King Phillip Climbed Over the Fence and Got Shot! 1. 2. The evolutionary history of a species or group of related species

Linnean system

Agenda Homework: read and annotate the reading on Gorillas and lice. Try to create a cladogram of the information. Grade practice quiz Introduction to Cladograms Cladogram practice Plants

Corrections B D C A Correct your quiz You have FIVE MINUTES Correct your quiz If you want to discuss the answer, put a STAR by the question Here are the answers: B D C A B Natural Selection D A C 1. B 2. A 3. C

New Learning Targets I can analyze the data provided by a phylogenetic tree or cladogram to determine the evolutionary history of the organisms described in the diagram In short: I can read cladograms I can use a data set to create a cladogram that represents a reasonable hypothesis about the evolutionary history of a group of related organisms In short: I can make a cladogram

Our Focus: Cladograms

Cladograms and Phylogenetic trees Diagrams that represent the evolutionary history of a group of related organisms Considered to be a hypothesis Best fit with existing data Subject to revision Based on whether or not an organism or group of organism has a specific trait What represents data? Fossil record Morphology (shape form) Molecular homologies (DNA, proteins) Big Question: who is the ancestor of who?

A Phylogenetic Tree

A Cladogram Time

Cladistics Based on 3 assumptions: Evolution happens: traits change over time Any group of organisms is related by descent from a common ancestor The pattern of descent is one of bifurcation (splitting in two)

Cladogram Terms Taxon (plural: taxa): a group of organisms Node: the point at which two branches on a cladogram meet; represents a common ancestor Can also represent a speciation event Synapomorphy: a characteristic shared by two or more taxa and the most recent common ancestor Clade: a group of taxa defined by a synapomorphy Show linnean relationships in terms of TREES

Generalized Cladogram Node common ancestor to A, B, and C Node

Vertebrate Cladogram synapomorphies

Clades Hair Amniotic Egg Four Limbs What makes different clades different it what they share Four Limbs

Assignment: Interpreting Cladograms Read each cladogram and answer the questions You will need to know the terms taxon, clade and synapomorphy You can work together to complete this assignment, but your goal is to LEARN Don’t let someone else carry the weight for you Cladograms increase in complexity

Plants We need to start counting the hairs on each of the plants and recreate the histogram