EvolutionEvolution

EvolutionEvolution –process through which species –process through which species change over time. The process by which change over time. The process by which modern organisms (multicellular) have modern organisms (multicellular) have descended from ancient organisms descended from ancient organisms (unicellular) (unicellular)

Jean Baptiste de Lamarck Jean Baptiste de Lamarck was the first scientist to was the first scientist to propose a model of how propose a model of how life evolveslife evolves

Lamarck’ s theory of acquired Lamarck’ s theory of acquired characteristicscharacteristics

Lamarck said Lamarck said organisms acquired organisms acquired traits by using their traits by using their bodies in new waysbodies in new ways

These new These new characteristics were characteristics were passed to offspringpassed to offspring

Lamarck was unable Lamarck was unable to provide an to provide an evidence to support evidence to support his ideashis ideas

Charles Darwin (1809-1882) Charles Darwin (1809-1882) Sailed around the world (1831-Sailed around the world (1831-1836)1836)

Brainpop - Charles Darwin

What did Darwin’s travels What did Darwin’s travels reveal?reveal?

The diversity of living The diversity of living species was far greater species was far greater than anyone had than anyone had previously known!!previously known!!

Darwin made Darwin made observations on his observations on his voyage that later became voyage that later became the foundation for his the foundation for his theory of evolution by theory of evolution by natural selectionnatural selection

How did the finches differ How did the finches differ among the islands of the among the islands of the

Galapagos?Galapagos? Darwin noticed differences Darwin noticed differences

between the finches on the between the finches on the island and those of the island and those of the nearby mainlandnearby mainland

Each island had its own Each island had its own type of finch that were type of finch that were clearly different from the clearly different from the other islandsother islands

Darwin specifically noticed Darwin specifically noticed the differences in the shape the differences in the shape of their beaks and in the of their beaks and in the food they atefood they ate

Darwin ThoughtDarwin Thought Darwin wondered why Darwin wondered why

the island finches were the island finches were

different from the mainland different from the mainland

finchesfinches He hypothesized thatHe hypothesized that

perhaps some finches wereperhaps some finches were

blown to the island by ablown to the island by a

storm and over time thestorm and over time the

finches that survivedfinches that survived

adapted to different waysadapted to different ways

of living on the islandsof living on the islands Darwin Finches

Darwin’s Thoughts Darwin’s Thoughts ContinuedContinued

Darwin looked to selective breeding for Darwin looked to selective breeding for cluesclues

selective breedingselective breeding - humans, not nature, - humans, not nature, select which traits will be passed along to select which traits will be passed along to the next generation (a farmer breeds only the next generation (a farmer breeds only his best livestock)his best livestock)

Darwin’s Thoughts Darwin’s Thoughts ContinuedContinued

Darwin proposed that nature works somewhat in the Darwin proposed that nature works somewhat in the same way… organisms that are better adapted are same way… organisms that are better adapted are able to survive and reproduceable to survive and reproduce

So they are somewhat “So they are somewhat “selected”selected” byby naturenature and pass and pass their helpful trait to their offspringtheir helpful trait to their offspring

Natural selectionNatural selection – members of a species that are best – members of a species that are best suited to their environment survive and reproduce at a suited to their environment survive and reproduce at a higher rate than other members of the specieshigher rate than other members of the species

Brainpop - Natural Selection

Darwin’s Thoughts ContinuedDarwin’s Thoughts Continued

MutationMutation – change in the DNA – change in the DNA- mutation causes no effect- mutation causes no effect-mutation is harmful-mutation is harmful-mutation is beneficial-mutation is beneficial

Beneficial mutations allow organisms to Beneficial mutations allow organisms to survive and reproduce at a higher ratesurvive and reproduce at a higher rate

Natural Selection Wins!Natural Selection Wins!

In 1859, Darwin In 1859, Darwin published his results in published his results in his book called his book called On the On the Origin of Species by Origin of Species by Means of Natural Means of Natural SelectionSelection

Darwin theorized that Darwin theorized that evolution occurs through evolution occurs through a process he called a process he called natural selection natural selection (survival of the fittest)(survival of the fittest)

Natural Selection in 4 Natural Selection in 4 StepsSteps

1. 1. OverproductionOverproduction--each species each species produces more produces more offspring than will offspring than will survive to maturity.survive to maturity.

2. 2. Genetic VariationGenetic Variation-- the individuals in a the individuals in a population are slightly population are slightly different from one different from one another. Some traits another. Some traits increase the chances increase the chances that the individual will that the individual will survive and reproduce.survive and reproduce.

3. 3. Struggle to Struggle to SurviveSurvive - - a natural a natural environment does not environment does not have enough food, have enough food, water, and other water, and other resources to support resources to support all the individuals all the individuals born. In addition, born. In addition, many are killed by many are killed by other organisms.other organisms.

4. 4. Successful Successful ReproductionReproduction - the - the individuals that are individuals that are well adapted to their well adapted to their environment are environment are more likely to more likely to survive and survive and reproduce.reproduce.

Natural Selection in 4 Natural Selection in 4 StepsSteps

Insecticide ResistanceInsecticide Resistance

Insects quickly develop resistance to Insects quickly develop resistance to insecticides because they produce many insecticides because they produce many offspring and usually have short offspring and usually have short generation times.generation times.

A A generation timegeneration time is the period between is the period between the birth of one generation and the birth of the birth of one generation and the birth of the next generation.the next generation.

In the 50 years that insecticides have been used, more than 500 species of insects have developed resistance to certain insecticides.

3 Ways Speciation Can Occur3 Ways Speciation Can Occur

1. 1. SeparationSeparation - a - a newly formed newly formed canyon, mountain canyon, mountain range, or lake are range, or lake are a few ways that a few ways that populations can populations can be divided.be divided.

2. 2. AdaptationAdaptation - if a population has - if a population has been separated, the environment may been separated, the environment may also change. To live the species must also change. To live the species must adapt to the new environment.adapt to the new environment.

3. 3. DivisionDivision - over - over thousand or millions of thousand or millions of generations, the two generations, the two groups of a population groups of a population may become so may become so different that they can different that they can no longer interbreed. no longer interbreed. At this point, they are At this point, they are no longer the same no longer the same species.species.

Peppered Moths of ManchesterPeppered Moths of Manchester Peppered moths spent most Peppered moths spent most

of their time resting on the of their time resting on the bark of oak tree trunks. Most bark of oak tree trunks. Most of the oak trees in England of the oak trees in England were light brown, speckled were light brown, speckled with green.with green.

Most of the peppered moths Most of the peppered moths at that time were light brown at that time were light brown too.too.

Some dark ones around, but Some dark ones around, but few.few.

Peppered Moths of ManchesterPeppered Moths of Manchester

Pollution from Industrial Pollution from Industrial Revolution stained Revolution stained London trees dark brownLondon trees dark brown

Suddenly scientists Suddenly scientists noticed the population of noticed the population of dark moths increased, dark moths increased, and the light moths and the light moths population decreasedpopulation decreased

Peppered Moths of ManchesterPeppered Moths of Manchester Birds were the moths major Birds were the moths major

predatorpredator

Birds can not see moths Birds can not see moths (prey) that blend in with (prey) that blend in with tree trunks because they tree trunks because they were camouflaged were camouflaged

The dark moths reproduced The dark moths reproduced which increased the which increased the population of dark mothspopulation of dark moths

Kettlewell- scientist who Kettlewell- scientist who studied peppered mothsstudied peppered moths

Fossils are Fossils are evidence evidence

of of Evolution!Evolution!

Fossil Rock Fossil Rock AnthemAnthem

Paleontology- study of extinct life

Fossils – remains of organisms preserved in the earth

 

Mastadon

Pterosaur

1. Fossils provide evidence about the history of life

2. Fossils show how organisms have changed over time

3. Fossil records are incomplete because most organisms die without leaving any trace!

T-Rex

Brittle Star

Vestigial StructuresVestigial Structures Vestigial StructuresVestigial Structures- body - body

parts that are reduced in parts that are reduced in size and have no functionsize and have no function

Whale evolutionWhale evolution Suggests that as the body Suggests that as the body

part was no longer needed part was no longer needed in the environment they in the environment they were lost or reduced in were lost or reduced in size size

ExamplesExamples hip and leg bones in hip and leg bones in

snakessnakes pelvic and femur bones in pelvic and femur bones in

whales suggest they once whales suggest they once had back legshad back legs

Older fossils are usually Older fossils are usually found in the bottom found in the bottom

geologic layer! geologic layer!