Evidence of Evolution &

Patterns of Evolution

Honors Biology

Evidence of Evolution

1. Biogeography – Plate Tectonics

2. Fossil Record

3. Comparative Anatomy - Vestigal

Structures

4. Comparative Anatomy -

Homologous/Analogous structures

5. Embryology

6. Molecular Biochemistry

1. Biogeography

• Geographical

distribution of species.

• Organisms tend to

arise in areas where

similar organisms

lived in the past.

2. Evidence from Fossils

• Scientists study fossils to obtain a record of the successive changes organisms have undergone.

• Fossils demonstrate change over time, the change is from simple to complex, and show the relative ages of two specific fossils.

• Evidence is not complete and can be easily disrupted.

What can be learned about an organism by

studying fossil skulls?

The size of the brain

As a species evolves, the size of the brain will

enlarge.

Law of

Superposition

Fossils and the rocks in which

they appear are in

chronological order from

oldest at bottom to youngest

at top. (strongest evidence)

Dating Fossils

Relative Age

describes approximate age of fossil relative to location.

Ex. “This fossil is located beneath that fossil, so it is relatively older.”

Law of superposition

Absolute age

Age of a fossil in years

Can be calculated

using radioactive

dating

Ex. “This fossil is

approximately 1

million years old.”

3. Evidence from Adaptations Traits suited to a particular environment that

allow organisms to survive

Inuit people, who live in the extreme cold of the Arctic, have short, stout bodies that conserve heat.

Masai people, who live in the arid lands of eastern Africa, have tall, lean bodies that disperse heat well.

Examples of AdaptationsInsecticides – Over the years many insects have become

resistant to the type of insecticides we have been using.

Why?

Species change – if a insect is susceptible to the insecticide they

will die, the ones that are not survive and continue to reproduce.

Round-Up Ready Crops – crops have been genetically

engineered to be resistant to round up, allowing the spray

to be used and not controlled by what it touches

These plants can get out in the wild or crossbreed creating “super

plants” that can no longer be controlled

Antibiotics – These are used to fight bacterial infections,

but have become less successful in some cases. Why?

The bacteria that are susceptible die of, leaving on the strong ones

to grow and multiple

Bird Beak Adaptations:

Adaptation vs. Acclimation

Adaptation (Evolution)Inherited characteristics of

organisms that enhance their

survival and reproduction in a

specific environment.

Acclimation

A physical change that

allows an organism to cope

with changed condition.

4. Evidence from Comparative

Anatomy

Structural similarities link related

species

Homologous/Analogous Structures

Vestigial Structures

Demonstrate how closely related

organisms are and how close their

common ancestor might be

Comparative Anatomy

Structures:

Homologous Structures: structures that are

similar because of common ancestry and

develop similarly

Traits of Homologous Structures:

1. Same ancestor

2. Same underlying structures

3. Different Functions

4. Different Environments

Examples of Homologous Structures

Homologous Structures:Same underlying structures, different functions,

different environments & common ancestor

Comparative Anatomy Structures:

Analogous:

1. Different ancestors

“analogy”=like

2. Different underlying

structures

3. Same Function

4. Similar Environments

Homologous:

1. Same ancestor

“homo”=same

2. Same underlying

structures

3. Different

Functions

4. Different

Environments

Comparative Anatomy

Structures:

Vestigial Structures

Structures that are present but not used by organism

Structures may have been useful to ancestors

These structures show a change has occurred over time

Examples:

In humans: tailbone, appendix

In whales: pelvic bone and four chambered

stomach

In snakes: pelvic bone, limb bones

5. Comparative Embryology

• Study of structures that appear during embryonic development.

• Embryos of different vertebrates show similar embryo development

5. Comparative Biochemistry

The more DNA

sequences species

have in common,

the closer they are

related

Molecular

Connection Lab

Differences in Biochemistry

DNA and proteins (amino acids)

Mutations are changes in the DNA.

Gene flow due to Immigration/Emigration

Gene flow is any movement of genes from one

population to another.

Immigration – into a population

Emigration – out of a population

Sexual Reproduction

Patterns of Evolution

Coevolution

Convergent Evolution

Divergent Evolution

Coevolution

The change in 2 or more species that are

closely associated with each other

Example:

• Acacia ants and acacia trees

• Humming birds and plants with flowers with long

tubes

Convergent Evolution

Species from different evolutionary branches may come to resemble each other even though they are not closely related

Example:

1. Ostrich (Africa) & Emus (Australia).

2. Sidewinder (Mojave Desert) &

Horned Viper (Middle East Desert)

3. Sharks and Dolphins

Divergent Evolution

2 or more species or related population

become more and more dissimilar

Can result in a new species

Types:

Adaptive radiation: related species evolve from

a single ancestral species (Galapagos finches)

Artificial selection: breeding organisms for

specific trait (dogs)

Final Thought:

Is it possible to develop an advantageous

characteristic within your own lifetime and

pass it on to your offspring?

Explain why or why not.