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.