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Taxonomy. Clades and Keys. Warm Up- 2/8. What did the salamander gain to evolve from the tuna fish?. Good Things. Worksheet. Title: Cladograms, Phylogenetic Trees, and Dichotomus Keys. Evolutionary Classification. Phylogeny = the study of evolutionary relationships
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Taxonomy Clades and Keys
Warm Up- 2/8 • What did the salamander gain to evolve from the tuna fish?
Evolutionary Classification • Phylogeny = the study of evolutionary relationships • Biologists now group organisms into categories that represent evolutionary descent (and not just physical similarities) How would you classify a hyena? Would you group it with cats or dogs?
Overview: Investigating the Tree of Life • Evolutionary theory is so important to modern biology that it is how biologist organize the modern world • Phylogeny is the evolutionary history of a species or group of related species usually organized into a phylogenetic tree • Phylogenetic trees and cladograms arrange organisms based on common ancestry and shared characteristics.
Cladograms • A diagram that shows evolutionary relationships
How to Read Cladograms Look at the cladogram at the right. What conclusions can be drawn about the relationship between humans and chimps?
How to read a cladogram • This diagram shows a relationship between 4 relatives. • Relatives share a common ancestor at the root of the tree. • The older organism is at the bottom of the tree. • The four descendants at the top of the tree are DIFFERENT species. This is called SPECIATION.
How to read a cladogram • Branches on the tree represent speciation • The event that caused speciation is shown as a fork on the tree.
How to read a cladogram • Species B and C each have characteristics that are unique only to them. • • But they also share some part of their history with species A. This shared history is the common ancestor.
What is the difference between a phylogenetic tree and a cladogram • Many biologists use these terms interchangeably • Some scientists associate phylogenetic trees with true evolutionary history • Some scientists consider cladograms to represent hypotheses about a group of organisms’ ancestry
What is the difference between a phylogenetic tree and a cladogram? • In phylogenetic trees branch lengths can represent the amount of genetic change or prediction to time • In cladograms the branch lengths are usually considered to be arbitrary Cladogram
Dichotomous Keys • A step-by-step guide to help identify an organism • Follows a series of choices that lead you to the organism’s name What am I??
1. Has green colored body ......go to 2 Has purple colored body ..... go to 4 2. Has 4 legs .....go to 3 Has 8 legs .......... Deerusoctagis 3. Has a tail ........ Deerus pestis Does not have a tail .....Deerus magnus 4. Has a pointy hump ...... DeerushumpisDoes not have a pointy hump.....go to 5 5. Has ears .........DeeruspurplinisDoes not have ears ......Deerusdeafus
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Warm Up- 2/11 • Which organism has the greatest genetic difference from the Spectacled Bear?
Taxonomy Foldable • Google Classroom