Evolution and Evolution and DarwinDarwin

EvolutionEvolution

Change over time

The processesprocesses that have transformed life on earth from it’s earliest formsearliest forms to the vast diversitydiversity that characterizes it today.

Theory-a well-supported testable explanation of events that have occurred in the natural world.

Old Theories of EvolutionOld Theories of Evolution

Jean Baptiste LamarckJean Baptiste Lamarck (early 1800’s) proposed:““The inheritance of The inheritance of acquired characteristics”acquired characteristics”

He proposed that by selective use or disuse of organs, organisms acquired or lost certain traits during their lifetime, which it passespasses on to its offspringoffspring.

““The Inheritance of Acquired The Inheritance of Acquired Characteristics”Characteristics”

Example:Example:

A giraffe acquired its long neck because its ancestor stretched higher and higher into the trees to reach leaves, and that the animal’s increasingly lengthened neck was passed on to its offspring.

Charles DarwinCharles Darwin

http://Early Life of Charles Darwin

Darwin set sail on the H.M.S. H.M.S. BeagleBeagle (1831-1836) to survey the South America South America to collect plants and animals.

On the Galapagos Islands, Galapagos Islands, Darwin observed species that lived no where else in the world.

These observations led Darwin to write a book.

Galapagos Islands

Charles Darwin InfluencesCharles Darwin Influences

James HuttonJames Hutton Proposed that Earth is Proposed that Earth is

shaped by geological forces shaped by geological forces that took place over long that took place over long periods of time.periods of time.

Thomas Malthus Thomas Malthus Proposed that famine, war

and poverty limited human population

Charles Darwin InfluencesCharles Darwin Influences

Charles LyellCharles Lyell led DarwinDarwin to realize that

natural forces gradually change Earth’s surface and that the forces of the past are still operating in modern times.

Charles DarwinCharles Darwin

Wrote in 1859Wrote in 1859:“On the Origin of Species by “On the Origin of Species by Means of Natural Selection”Means of Natural Selection”

Artificial selection-humans selected the Artificial selection-humans selected the genetic variation that they found usefulgenetic variation that they found useful

Proposed a mechanism for evolution:Proposed a mechanism for evolution:NATURAL SELECTION-NATURAL SELECTION- nature selected the genetic nature selected the genetic

variation that they found usefulvariation that they found useful

Artificial SelectionArtificial Selection

The selective breedingselective breeding of domesticated plants and animals by man.

Question:Question:

What’s the ancestor of the domesticated dog?

Answer:Answer: WOLFWOLF

Natural SelectionNatural SelectionIndividualsIndividuals with favorablefavorable traitstraits are more

likely to leave more offspring better suited for their environmentenvironment.

Can’t be seen but results shown

Example:Example:

English peppered moth (English peppered moth (Biston betulariaBiston betularia))

- light and dark phases- light and dark phases

Evolution by Natural Selection

Struggle for ExistenceMembers of species regularly compete for food,

living space, and other necessities.

Survival of the FittestFitness: ability of an individual to to survive and

reproduce in its environmentAdaptation: inherited characteristic that

increase an organism chance of survivalSURVIVAL OF THE FITTEST-Survive and

reproduce the most successfully

Struggle for Existence

Evolution by Natural Selection

Descent with ModificationAll living organisms

are related to one another

Common DescentSingle “Tree of Life”All species were

derived from common ancestors

Intermission

Fossil Records

Evidence of EvolutionEvidence of Evolution

1.1. Fossil Record: Fossils Fossil Record: Fossils and the order in which and the order in which they appear in layers of they appear in layers of sedimentary rock sedimentary rock (strongest evidence).(strongest evidence).a.a. Ancestral traits-primitive Ancestral traits-primitive

features that do appear in features that do appear in ancestral formancestral form

b.b. Derived traits-newly evolved Derived traits-newly evolved features that didn’t appear features that didn’t appear in ancestorsin ancestors

Evidence of EvolutionEvidence of Evolution

2.2. Biogeography: Biogeography: Geographical Geographical distribution of distribution of species.species.

Evidence of EvolutionEvidence of Evolution

3. Comparative AnatomyHomologous Structures

-Structures that has different mature form but develop from same embryonic tissue.

Vestigial structure

-Structure that is no longer functioning

Analogous structures

-Structures that has same mature form but develop from different embryonic tissue.

Evidence of EvolutionEvidence of Evolution

4. 4. Comparative embryologyComparative embryologyStudy of structures that Study of structures that appear during embryonic appear during embryonic development.development.

5. Molecular biology:5. Molecular biology:

DNA and proteins (amino DNA and proteins (amino acids)acids)

AdaptationAdaptation: a trait shaped by natural

selection that increases an organism's reproductive success

Fitness: a measure of the relative contribution success of the following generation

Types of adaptationCamouflageMimicry Antimicrobial resistance

Summary of Darwin Theory

Individual organisms differ and some of the variation is Individual organisms differ and some of the variation is heritable.heritable.

Organisms produce more offspring than can survive and Organisms produce more offspring than can survive and many that survive don’t reproducemany that survive don’t reproduce

They will compete for limited resourcesThey will compete for limited resources Each unique organisms has different advantages and Each unique organisms has different advantages and

disadvantages in the struggle of existence.disadvantages in the struggle of existence. Individuals best suited to their environment and Individuals best suited to their environment and

reproduce most successfully.reproduce most successfully. Species alive today are descended with modification Species alive today are descended with modification

from ancestral species that lived in the distant from ancestral species that lived in the distant pastpastSingle tree of life.Single tree of life.

Video

Darwin: Dangerous Idea