Notes Ch 182 Evolutionary Classification Modern classification is based on evolutionary theory Phylogeny study of how orgs are related to each other their evo relationships Evolutionary Classification ID: 719625
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Slide1
Modern Evolutionary ClassificationNotes-Ch. 18.2Slide2Slide3
Evolutionary ClassificationModern classification is based on evolutionary theoryPhylogeny – study of how orgs are related to each other (their evo relationships)Evolutionary Classification
– grouping organisms based on their evolutionary historySlide4
Homologous StructuresOne way to discover relationships is by comparing anatomical structures (body organs and parts).Parts that are alike in basic structure and origin in several organisms but are not used for the same reason are called homologous structures.Ex. All above have the same bones and number, used differently- evidence points to common ancestor.Slide5
CladogramsCertain features shared by different group of organisms are known as “derived characters.”Derived characters – characteristics that are in recent parts of lineage but not in older membersUsed to make cladograms (aka phylogenetic tree)
The more derived characteristics two organisms share, the closer their evolutionary relationshipSlide6
Common Ancestor
Relative Time
Largest difference
Moderate difference
Small difference
Smallest difference
Sample Evolutionary TreeSlide7
TRADITIONAL CLASSIFICATION
CLADOGRAM
Appendages
Conical Shells
Crab
Barnacle
Limpet
Crab
Barnacle
Limpet
Crustaceans
Gastropod
Molted exoskeleton
Segmentation
Tiny free-swimming larva
Section 18-2
Traditional Classification Vs Cladogram
Go to Section:Slide8
TRADITIONAL CLASSIFICATION
CLADOGRAM
Appendages
Conical Shells
Crab
Barnacle
Limpet
Crab
Barnacle
Limpet
Crustaceans
Gastropod
Molted exoskeleton
Segmentation
Tiny free-swimming larva
Section 18-2
Go to Section:
Traditional Classification Vs CladogramSlide9Slide10
DNA & RNAAll living things have itCompare organisms by genesMore similar = more recent common ancestorSlide11
Molecular ClocksEstimates amount of time since species divergedUses mutations as markersCompare similarities and differences in genesSlide12
Quick LabIdentify the organisms in the table that is the least closely related to the others.
Construct a cladogram of these animals. Do NOT copy the table.
Analysis questions on next slide.
Derived Characters in Organisms
Organism
Derived Characters
Backbone
Legs
Hair
Earthworm
Absent
Absent
Absent
Trout
Present
Absent
Absent
Lizard
Present
Present
Absent
Human
Present
Present
PresentSlide13
3. Analysis QuestionsWhat trait separates the least closely related organism from the other animals?List the animals in your cladogram in order of distance from the least closely related organism.
Explain if your
cladogram
indicates that lizards and humans share a more recent common ancestor than either does with an earthworm.
Where would you insert a frog if you added it to the
cladogram
? Explain your answer.Slide14
Extra Practice1. Construct a cladogram for the info above. 2. Three previously unknown vertebrates have been discovered in a rainforest in South America. a. “rat-like creature” b. “iguana-like creature”
c. “goldfish-like creature”
Place these animals on your cladogram and justify your placement.
Derived Characters in Organisms
Organism
Derived Characters
Backbone
Placenta
Foramen Magnum Forward
Tuna
Present
Absent
Absent
Horse
Present
Present
Absent
Human
Present
Present
Present