Modern evolutionary classification notes ch 18 2
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Modern Evolutionary Classification Notes- Ch. 18.2. Evolutionary Classification. Modern classification is based on evolutionary theory Phylogeny – study of how orgs are related to each other (their evo relationships)

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Modern Evolutionary Classification Notes- Ch. 18.2

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Modern evolutionary classification notes ch 18 2

Modern Evolutionary ClassificationNotes-Ch. 18.2


Evolutionary classification

Evolutionary Classification

  • Modern classification is based on evolutionary theory

  • Phylogeny – study of how orgs are related to each other (their evo relationships)

  • Evolutionary Classification – grouping organisms based on their evolutionary history


Homologous structures

Homologous Structures

  • One 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.


Cladograms

Cladograms

  • Certain 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 members

  • Used to make cladograms (aka phylogenetic tree)

  • The more derived characteristics two organisms share, the closer their evolutionary relationship


Modern evolutionary classification notes ch 18 2

Sample Evolutionary Tree

Small difference

Common Ancestor

Largest difference

Moderate difference

Smallest difference

Relative Time


Modern evolutionary classification notes ch 18 2

Traditional Classification Vs Cladogram

Section 18-2

Appendages

Conical Shells

Crustaceans

Gastropod

Crab

Crab

Limpet

Limpet

Barnacle

Barnacle

Molted exoskeleton

Segmentation

Tiny free-swimming larva

TRADITIONAL CLASSIFICATION

CLADOGRAM

Go to Section:


Modern evolutionary classification notes ch 18 2

Traditional Classification Vs Cladogram

Section 18-2

Appendages

Conical Shells

Crustaceans

Gastropod

Crab

Crab

Limpet

Limpet

Barnacle

Barnacle

Molted exoskeleton

Segmentation

Tiny free-swimming larva

TRADITIONAL CLASSIFICATION

CLADOGRAM

Go to Section:


Dna rna

DNA & RNA

  • All living things have it

  • Compare organisms by genes

  • More similar = more recent common ancestor


Molecular clocks

Molecular Clocks

  • Estimates amount of time since species diverged

  • Uses mutations as markers

  • Compare similarities and differences in genes


Quick lab

Quick Lab

  • Identify 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.


3 analysis questions

3. Analysis Questions

  • What 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 cladogramindicates 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.


Extra practice

Extra Practice

1. 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.


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