Evolution

• Evolution is the change in genes in a population over time

• Evolution helps us understand the history of life

• Present-day species evolved from earlier species

What is a population?

Members of the same species living in a certain location at a specific time

Evolution does NOT take place in an individual

The changes in the genes (sections of DNA) must be passed on to another generation

Types of evidence used to support the

Theory of Evolution:

A. Biogeography

B. The Fossil Record

C. Embryology

D. Comparative Anatomy

E. Biochemical Analysis

Biogeography

• The study of where species are located on the Earth

• Organisms change over time due to environmental changes/stresses

A. Biogeography

Organisms found on islands share features with species on the mainland

– Galapagos Islands• Finch birds• Tortoises

Islands with similar environments have similar species

AdaptationsOrganisms change over time due

to environmental stresses

Three types of adaptations:

• Structural• Behavioral• Physiological/function

B. Fossil Record

Paleontologists study records

Fossil records reveal the chronological order of vertebrates is:

1. FISH first appeared on Earth then came…2. AMPHIBIANS3. REPTILES4. BIRDS5. MAMMALS

Types of fossils

• Imprint• Mold• Casts• Petrified samples• Frozen samples• Amber—sap from

trees

C. Comparative Embryology• Study of early stages of development before birth

Timing of stages and new features reveals evolution/history of ancestors

• New features in different organisms came from the remodeling of ancestral structures

Examples: – jaws and inner ears develop from gill slits

Gill slits in red

Gills still present in fish and some salamanders

Embryology and Fossils

• Snakes have legged ancestors– Some species have hind (rear)

limb buds as early embryos– They lose the buds and develop

into legless adults– Fossil evidence of snakes with

hind limbs exists – Suggests snakes evolved from a

limbed ancestor

D. Comparative Anatomy

Do birds have phalanges?

Do cats have lumbar vertebrae?

Do frogs have a humerus bone?

Scientists study homologous, analogous, and vestigial structures to show evolutionary relationships

Homologous Structures

– Share the same pattern of structure—arm bones

– Have a recent common ancestor

– Come from the same part of the embryo

– May or may not perform the same function

Analogous Structures

– Body part different in structure such as wings

– Share a different origin and development

– Yet similar in function

Vestigial Structures

Fully developed in some organisms,

yet reduced or functionless in others

Examples:– Hip bones in snakes and hip bones in

humans

– Eyes in blind cave fish

E. Biochemical analysis

Molecular level living things are very similar

• DNA/RNA code

• proteins for building blocks

• ATP for energy

• sugars for fuel

• genes for traits

Biochemical analysis

--Protein synthesis follows the same process in eukaryotes

DNARNARibosomesProteins

--Roundworms share 25% of their genes with humans

Biochemical analysis

Examples:

--Insulin may control sugar levels in numerous species

--Animal cells and plant cells use glucose for making energy

Evolutionary pattern of the Animal Kingdom

ProtocellsProkaryotesEukaryotes

ProtistsInvertebratesVertebrates

Evolution Review

• What is the definition of evolution?

• What are the types of evidence for evolution?

• Describe (explain and provide examples) of each type of evidence.

• What is the evolutionary pattern for members of the animal kingdom?

• Organisms are grouped based on_____?

Classification of organisms

• Organisms are grouped based on similarities such phenotypes and evolutionary history

• The study of classification is called taxonomy