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Bio 9D: Thursday, 4.28.11 Title: Evidence for Evolution. Homework : None Silent Do Now: (in NB w/ title and date) As you know, different organisms are related to each other through evolutionary history – this means that they share a common ancestor. - PowerPoint PPT Presentation
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Bio 9D: Thursday, 4.28.11 Title: Evidence for Evolution
Homework: None Silent Do Now: (in NB w/ title and date)
As you know, different organisms are related to each other through evolutionary history – this means that they share a common ancestor.
1. What are some species that you think are close evolutionary relatives of humans? What are some more distant evolutionary relatives of humans?
2. What types of evidence could a scientist use to prove that certain species are close or distant relatives?
Today’s Objectives: Explain the 3 types of homologies and use them as
evidence to build evolutionary trees.
Evolution Dry Lab Part APart A Computer LabAll in the Family: Which Animals are the Closest
Relatives? Link:
http://www.pbs.org/wgbh/evolution/change/family/index.html
The purpose of this series of lab activities is for you to…
Examine and understand the evidence for evolution Use that evidence to infer evolutionary
relationships and build phylogenetic treesObjectives for Class:
• Use the three different types of homologies as evidence for evolutionary relationships
Bio 9D: Monday, 5.2.11 Title: Evidence for Evolution – Day 2
Homework: Complete Evidence Lab Part A and the Ppt. Notes if you haven’t finished by the end of class.
Silent Do Now: (in NB w/ title and date)Go back to your class notes from 4/13/111. What is the difference between micro-evolution
and macro-evolution? Give an example of each.2. Which is easier to understand and believe, micro
or macro? Why? Today’s Objectives:
Explain the 3 types of homologies and use them as evidence to build evolutionary trees.
Micro-Evolution Small-scale Changes in a population’s gene pool over
time Caused by natural selection and/or
genetic drift
Example: Average beak size in a population of birds increases over several generations.
Micro-evolution leads to Macro-evolution
Objectives for Class:• Use actual evidence to explain how the four principles of natural selection shape the evolution of
organisms
Large-scale, often over a very long time Branching of one species into two
species Leads to the idea that all species share a
common ancestor
Example: Evolution of whales from four-legged land mammals
Macro-Evolution
Objectives for Class:• Use actual evidence to explain how the four principles of natural selection shape the evolution of
organisms
EVIDENCE FOR EVOLUTIONWhat is the evidence that all species on
earth are related to each other and share common ancestors?
Overview:3 Major Types of Evidence: 1. Homologous Structures
a) Anatomical homologies and vestigial structures
b) Embryological/ Developmentalc) Molecular/Genetic
2. Fossils3. Geographic Distribution of Species
Objectives for Class:• Describe the three different types of homologies and give examples of each
HOMOLOGOUS STRUCTURES – Similar structures due to sharing a common
ancestor that had those structures
Objectives for Class:• Describe the three different types of homologies and give examples of each
Anatomical Homology – similar body parts or bone structures
Don’t necessarily have the same function now, but did in the common ancestor
Ex: human arm, cat leg, whale flipper, bat wing all have same bones
Objectives for Class:• Describe the three different types of homologies and give examples of each
Anatomical Homology, continued:
Vestigial Traits - Don’t have a function now,
but suggest that they descended from an ancestor that did use them.
Examples: human tailbone, human goose
bumps, ostrich wings
Ex: human tail bone, human goose
www.toptenz.net
animal.nationalgeographic.com
Objectives for Class:• Describe the three different types of homologies and give examples of each
Embryological/Developmental Homology
Similar characteristics appearing during specific embryonic/ developmental stages of development
Examples: fish, reptile, bird, and human embryos all have gill slits and a
tail (but some lose these features before birth)
Objectives for Class:• Describe the three different types of homologies and give examples of each
Molecular/Genetic Homology Similarities between DNA or amino acid
sequences for different organisms Closer the similarities = Closer relationships
Objectives for Class:• Describe the three different types of homologies and give examples of each
Don’t confuse Homologous Structures with Analogous Structures
Analogous Structures structures that have the same function but NOT the same
skeletal structure This suggests these organisms did NOT descend from a common
ancestor with that trait
Ex: insect wing and bird wing
bio.miami.edu
Insect wing
Bird wing
Objectives for Class:• Describe the three different types of homologies and give examples of each
If you finish early: Go to http://tiktaalik.uchicago.edu/meetTik.htmland explore the information about Tiktaalik. Click the green buttons to read more and get to interactive features.To earn extra credit for this, write a summary of at least 3 pieces of evidence that support the idea that the first 4-legged animals evolved from this fish.
Notes stop here.