Evolution:

Evidence of Change

Evolution:

Evidence of Change

Charles Darwin (1809-1882)

•1831 Set sail on a 5 year voyage on the HMS Beagle around the world, and noted the diversity of life. Found ↑ diversity & similarities w/ adaptations to fit climate, environment, geography

•Fitness – A combination of physical traits and behaviors that help organisms survive and reproduce.

•Fitness arises from Adaptations that help an organism become better suited for their environment.

Question

• What EVIDENCE did Darwin find to support his Theory of Evolution?

Similarities in Body Structures

~Homologous Structures~Structures similar in origin and structure, but show

different needs and appearance.

~Vestigial Structures~

Appendix- Non-functioning in humans, but in koala bears and rabbits who eat lots of flora, it helps to further digest their food.

• Coccyx – tail bone traced to ancestors to support a tail.

• Male Nipples – Males & females born with nipples & ducts intact. Presence of genes that direct hormones to differentiate the breast tissue. Other genes on

Y-chromosome stimulate testosterone to form male features.

Organs that are reduced in sized and no longer function.

~Analogous Structures~Structures that are similar in appearance and function, but have different origins.

Butterfly – has exoskeleton, forms membranous wing

Birds – skeletal structure from which the wing is formed.

Similarities in ~Biochemistry~

Evidence: similarities of Early Development

similar genes at work

Embryo Development

• As embryo grows & develops similarities disappear

caused by genes that have

changed with Evolution

Mutations

+Mutations adaptation & increased fitness passed on

-Mutations less fit & not passed on

Age of EarthContributes to Darwin’s Theory

• James Hutton 1788: geologist argued earth very old & changed through gradual weathering, volcanoes, natural forces

• Charles Lyell 1830: Earth changed gradually/slowly must be used to explain past events

Both used to support Darwin’s Theory of evolution

Geological Time Scale

Fossilspreserved remains of ancient organisms

(paleontology- study of fossils)

• Relative Dating: Technique used to determine age of fossils relative to other fossils in different layers of rock (fossils found deeper are older)

• Absolute dating: radioactive decay measured in ½ life to determine age of rock.

½ life: length of time required for ½ of the radioactive atoms in a sample to decay.

C-14 (1% from env.) ½ life 5500yrs (½x½=¼11,000 yrs

U-238 (1/2 life 4.5by) K-40 (1/2 life 1.3by)

Fossil Record is INCOMPLETE!

What Fossil Record Shows

• Evolutionary history of organisms • Changes in Earth’s climate &

geography• Organisms simple complex

Fossil Record shows change in living organisms followed

changes in Earth

Types of Fossilsplants/animals replaced with mineral compounds petrified (turned into

rock)

• Sedimentary rock particles carried by streams, rivers, lakes, seas settle & embedded in layers of rocks (older deeper)

• Cold trapped in ice• Tree sap/Amber traps insects• Quicksand, peat bogs, tar pits no

oxygen so decomposition is slowed

Lizard in amber

Prehistoric termites in amber

Frog in amber

Dragonfly in amber

Fly preserved in amber for over 3 million years

Fossils - evidence of past life

 

                                                                                                                              

                                           

PetrifiedTurned to stone. The soft parts of the organism are replaced with minerals.

                                           

Imprint on a rockTurned to stone. The imprints are replaced with minerals.

                                                              

Animal trapped in frozen iceOrganisms trapped in glaciers, ice caves, and avalanches. Soft body parts stay preserved.

  

                                        

 

man buried in a peat bog for over 2,000 years

Bones preserved in tar pitsOrganisms trapped in tar pits. Soft body parts stay preserved.

                                          

An insect trapped in hardened plant sap (amber)Organisms trapped liquid tree sap. Soft body parts stay preserved.

                                 

Cast of the organism bodyLike an imprint the shape of living organism is turned into stone leaving the reverse shape.

                                                                           

Cast of the organism bodyLike an imprint the shape of living organism is turned into stone leaving the reverse shape.

An insect trapped in hardened plant sap (amber)Organisms trapped liquid tree sap. Soft body parts stay preserved.

Adaptations

Morphological – inherited structural, anatomical,

or physical change that ↑’s fitness

[Ex: Panda’s thumb, fish gills lungs]

Physiological – inherited changes that regulate functions w/in individual Ex. Biochemistry controlled enzymes, hormones that ↑’s fitness

Ex: Antarctic ice fish produce chemical antifreeze prevents them from freezing

Behavioral – Inherited changes in how an organism acts that ↑’s fitness

Reflexes, Instincts, hibernation, migration.

Any inherited feature that increases the chance of surviving and reproducing.

Jean Baptiste de Lamark(1744 – 1829)

• Recognized that living things adapted and change over time.

* Desire to Change – Inborn urge to become better fit for environment.

[Ex: Moths didn’t know they needed

to change color*] FALSE

* Use & Disuse - “Use it or Lose it.” Change occurred because organisms could alter their shape by using their bodies in new ways. Organs could increase in size, shape, function, etc., depending on needs. [ Ex: Giraffe’s neck grows to reach the tallest leaves on the trees.] FALSE

* Passing on Acquired Traits – If an animal acquired body structures during its lifetime, change could be passed down to its offspring. [Ex: Parent build up muscle to have muscular children.] FALSE

Jean Baptiste de Lamark’sTheory of Evolution

Charles Darwin’s (1809-1882) Theory of Evolution:1. The Age of the Earth

~long periods of time were needed for a species to have evolved from a

Common Ancestor.~Hutton Earth very old Lyell events gradual like changes on Earth

2. Natural Selection

– The environment selects what can/cannot survive.

Charles Darwin’s (1809-1882) Theory of Evolution

Thomas Malthus 1766-1834

↑ populations ↑competition

for resources

Darwin: Survival of the fittest

Struggle for existence

Natural Selection~Tested~

• Peppered Moths – (early 1800’s) • Most Moth’s were light brown blend, darker

moths were eaten by birds.• Industrial revolution produced soot that

darkened the trees of England.• Change occurred: Light colored Moths were

being seen and eaten by birds. • Dark colored Moths were surviving due to

camouflage. (Population of Dark Moths grew).• Increase in Gene Frequency of Dk. Colored

Moths in Gene Pool of that area.

• Conclusion: Better Camouflage Moths survived according to their Environment.

Genetics

Artificial Selection – human intervention to ensure only desirable traits are bred. [Ex: livestock, crops, dogs, cats]

Genetics & Evolutionary Theory• Darwin did not know how inherited traits were

important to his theory of evolution & how they were passed on

• Fitness, adaptation, species & evolutionary change defined through genetics

• Genes that give “fitness” survival of the fittest are inherited by offspring

• Natural Selection / environment chooses

• Genes carry inheritable characteristics, source of random variation for Natural Selection

Genetics Drives Evolution

Terms

• Gene Pool: common group of genes (each gene pool contains a # of alleles/ forms of a gene) w/in a species

• Relative Frequency: # of times an allele occurs in a gene pool compared to # of times other alleles for same gene occur (Ex. peppered moth)

• Evolutionary change: involves a change in the relative frequency of alleles in gene pool of population of a species

• Species: group of similar organisms that can breed/ produce fertile offspring

• Members of species can breed so share common gene pool.

• Allows for genetic changes in 1 individual to be spread through population as individual and ITS offspring mate

• If genetic change ↑ fitness (ability to survive/reproduce) gene will be found in many individuals in population

Genetic Drift

• The random change in the frequency of a gene. (Chance!)

• Seen more in smaller populations.

• Larger populations can absorb the drift in frequency.

• May result when an individual of a certain allele produces more offspring vs. others by chance.

• Polydactyl- have +5 digits on fingers or toes.

Solve for genetic driftA species of fox live on a mountainsideThere are an equal number of tan fox &

tan fox with purple spotsThere are an equal # of males & females

for each groupColor has nothing to do with fitnessGive 2 examples with explanations of how

genetic drift could occur.

Remember it’s random/chance

Divergent Evolution = Adaptive Radiation

Divergent Evolution1 species gives rise to many different species that are similar

internally, but not in physical appearance.

Speciation –How new species evolve from old ones diversity.

separation of populations, don’t interbreed

separation of gene pool in one group that doesn’t

show in another….leads to 2 distinct species

Natural selection increases differences between separated populations.

*Adaptive Radiation* 1 species gives rise to may. Organisms evolve a variety of characteristics that enable them to survive in different niches.

Homologous Structures (same origin)

Speciation

• Niche: how organism uses its resources and place where it lives (habitat)

• Species: can breed fertile offspring & share common gene pool

Process of Speciation• Reproductive Isolation: separation of

population separates gene pools so adaptations in 1 group don’t appear in another 2 species

Results from: Geographic barriers (rivers, mtns, streams, roads, etc) prevents breeding

Behavioral Isolation Temporal Isolation (mating times)Natural Selection ↑ differences between separated

populations physical & behavioral barriers different gene pools new species b/c they no longer interbreed

Darwin’s Finches>14 species on Galapagos islands evolved from

single S. American mainland ancestral speciesAll exhibit body structures & behaviors that

enable it to live in different niche

Speciation of Darwin’s Finches• Some finches separated from mainland

(lost, blown off course, storm) travel to Galapagos Islands

• Separation of Populations (gene pool separates)

• Over time each population adapts to needs of their environment (beaks size, shape, etc)

• Reproductive Isolation: gene pools no longer mixed speciation

Sharing the Island

• New species can coexist if occupy different niches

• Extinction if occupy same niche (no 2 species can occupy same niche/ competition leads to extinction of 1

• Further evolution in a species so they occupy different niche (different food source/shelter/resources so ↓ competition

Convergent Evolution• A process in which organisms not closely related

independently inherit similar characteristics while evolving in separate ecosystems but similar environments

Analogous Structures have different origins and structures, but similar function.

• Ex 1:The flippers of whales & the fins of fish.• Ex 2:Butterfly wings & Birds wings.• Ex 3:Shark (fish gills) & dolphins mammal lungs

Punctuated EquilibriumPattern of long, stable periods interrupted by brief

periods of change.

•Existence of mass extinctions is not direct evidence of punctuated equilibrium but rather periods of extremely rapid and/or catastrophic environmental change

Gradualism• James Hutton showed

through sedimentary rock, petrified fossils created a Fossil Record. Fossil Record provides evidence that evolution was slow and gradual.

• Charles Darwin believed in gradualism organisms adapted and changed over long periods of time. He supported Hutton’s work.

Gradualism vs Punctuated Equilibrium

Gradualism: slow change over long periods of time

Punctuated Equilibrium: long periods of no change followed by periods of rapid change.

(catastrophic events)

Microevolution

• Evolution witnessedBacterial resistance and new strainsMutations occur that enable bacteria to

evolve & outsmart antibiotics favorable adaptation for bacteria survival of the fittest natural selection

Reproduce quickly with many offspring change/evolution that can be seen

Evolution of Man (Homo sapiens)Hominid: Member of the evolutionary

line that produced humansClassified in Family Hominindae

CladogramsDiagram that shows evolutionary

relationships among a group of organismsDinosaurs evolved from thecodonts. Crocodiles, dinosaurs, birds all arose from early reptiles called thecodonts.