Evolution natural selection_and_speciation 6 kings

“Evolve” Means to Change Over Time

The belief that life on Earth has changed over time is quite old

To be considered science, this belief requires a great deal of evidence

The Development of Evolutionary Theory Naturalists have always wondered at the diversity of living things………Great varieties in shape, size, and ecological roleEstimated 3 million to 20 million different living speciesMuch of the natural world’s biodiversity has vanished through extinction99% of all species that ever lived are now extinctPermian-Triassic Mass ExtinctionWhat Killed the Dinosaurs?

Development of Evolutionary Theory

What could cause such great diversity, and why have so many species died out?

Charles Darwin offered an explanation based on careful observations

Who was Charles Darwin?

Development of Evolutionary Theory

Darwin Concluded:Physical traits and behaviors enable organisms to survive and reproduce (called Fitness )Fitness results from adaptationsDarwin reasoned that adaptations result from natural selection and result in evolutionEvolution is the process by which living Evolution is the process by which living

things change and diversify over timethings change and diversify over time

Development of Evolutionary TheoryThese ideas were widely challenged

until a tremendous amount of evidence was gathered to support evolution!

Now…The Theory of Evolution is the Cornerstone of BiologyExplore the Evolution Revolution

Natural Selection and Speciation

Charles Darwin

Studied Medicine and TheologyExcelled in Geology and BiologyIn 1831 Darwin joined the H.M.S. Beagle on a trip around the world to make mapsHe was the ship’s naturalistDarwin’s Diary

Darwin Pieces Together the Puzzle

Collecting fossils and other specimens

Making detailed observations of animal behavior

Making detailed drawings of the organisms he encountered

Darwin traveled South America & Galapagos Islands

The Voyage of the Beagle: Ports of Call

Noted that populations Noted that populations of organisms were of organisms were slightly different from slightly different from place to placeplace to place

Each group was Each group was modified to their modified to their specific environmentspecific environment

The Galapagos ArchipelagoThe Galapagos Archipelago

Land Iguana

Marine Iguana

The Origin of Species Interactive Exploration

Charles Lyell


Author of “Principles of Geology”

This book helped Darwin realize that the earth is old and changes slowly over time.

Malthus wrote “Essay on the Principles of Population”

Populations will always grow larger than the food supply, creating hunger, disease and struggle/competition. Some people live, others die.


Thomas Malthus

18th Century Economist

Darwin coined the term Artificial Selection - the process of modification of a species through human actions which encourage the breeding of certain traits over others.


http://www.esp.org/books/darwin/variation/facsimile/title3.html

What Darwin Learned from Artificial Selection

When chosen organisms are mated, desired characteristics are formed (Darwin didn’t know about DNA)

Individuals in the wild who possess characteristics that make it more likely for them to reproduce will pass along these characteristics to their offspring.

“Desirable" characteristics, in the wild, would be those which enhance survivability, NOT those which specifically satisfy human needs. Nature does the selecting.


Lamarck’s View of Evolution

Stated that acquired characteristics can be passed on to offspring.


Darwin’s View of Evolution


Those giraffes with longer necks got more food and were better able to survive to reproduce, passing on the long-neck genes to their offspring. Over time, giraffes evolved longer necks.

4 Key Ideas of Natural Selection

“Of course, long before you mature, most of you will be eaten.”

Evolution Through Natural Selection1. Variation (genetic) is present in the

population and this variation is inherited (genetically passed to offspring).

(Praying Mantis Camouflage)

2. Living things Overproduce3. Competition for Limited Resources4. Survival of the “Fittest”

Reluctantly published On the Origin of On the Origin of Species Species in 1859in 1859Video

Natural Selection

4 Main Points of Natural Selection

1. Variation (genetic) is present in the population and this variation is inherited (genetically passed to offspring).

2. Living things Overproduce

3. Competition for Limited Resources

4. Survival of the “Fittest” Video

Natural Selection

Fitness DefinedOrganisms who better survive to produce larger numbers of offspring are considered more fit than others who do not.

The Fittest Survive

Darwin Today…Natural Selection in action…

causes a frequency

of certain alleles in a population to increase or decrease over time!

Click the Link Below to Access the Cartoon

http://evolution.berkeley.edu/evolibrary/article/0_0_0/sneakermales_01

Read the cartoon carefully and answer the discussion questions on a separate sheet of paper.

Speciation Results in Biodiversity

SpeciationNatural Selection modifies populations. Some evolutionary changes are so great that some organisms can no longer interbreed with the original populationA new species resultsSpecies

An interbreeding population of organisms that can produce healthy, fertile offspring

Reproductive Barriers and Speciation

Prezygotic: gametes never meet and fuseGeographic isolation (allopatric speciation)Ecological isolationBehavioral isolation (lacewing songs)Mechanical isolationSeasonal isolation

Postzygotic: genetic differences manifestHybrid inviabilityHybrid sterility (tigons and ligers)

Geographic Isolation

2 populations separated by geographic barriers (rivers, mountains, bodies of water)

Abert Squirrel vs. Kaibab Squirrel

Temporal Isolation (Seasonal)

Species reproduce at different times

Behavioral Isolation

Differences in courtship rituals or other types of behavior

Songs of birds

Behavioral Isolation

Mechanical Isolation

Mating/Pollination is often impossible between different animal/plant species because of the incompatible shape and size of the reproductive structures.

Size Does Matter!

Example – Black and White Sage Plants

Black sage and white sage plants invite different pollinators

White sage flowers have large landing platforms for large pollinators causing the large pollinators to brush against the stamens, but the small ones usually don’t.

Black sage flowers have small landing platform for small pollinators. Therefore, the small pollinators cannot spread pollen to the white sage flowers therefore cross pollination is no longer possible.

Land Iguana

Marine Iguana

Two populations live in different habitats and mating occurs in those habitats, thus their own gene pool.

Ecological Isolation

After Mating Genetic Differences Occur

Hybrid sterility (tigons and ligers)(Horse and a donkey = mule – sterile)

Patterns in EvolutionAdaptive Radiation

Development of numerous new species from a common ancestor in diverse environmentsDarwin’s Finches (Origin of Species Activity)

GradualismPunctuated Equilibrium

Evolution Produces Biodiversity

Evolution Produces DiversityAll living things are classified by characteristics into 6 kingdoms of life

Archaebacteria

Autotrophic and heterotrophic speciesUnicellularProkaryoticCell wall w/o PeptidoglycanSome mobile

Ancient bacteriaLive in extreme environments (extremeophiles)Methanogens, Halophiles, Thermoacidophiles

Eubacteria

Autotrophic and heterotrophicUnicellularProkaryoticCell wall with PeptidoglycanSome mobile

True bacteriaE. coli, Streptococcus

Protist

Autotrophic and heterotrophicMostly multicellularEukaryoticCell wall on mostSome mobile

“Odds and ends” KingdomAmoeba, Paramecium

Fungi

Heterotrophic Mostly multicellularEukaryoticCell wall made of chitin Immobile

Mostly live on decaying organic matterFungi, yeast, mold

PlantAutotrophicMulticellularEukaryoticCell wall made of celluloseImmobile

Produce oxygen through photosynthesisTrees, shrubs, grasses, flowers

AnimalHeterotrophicMulticellularEukaryoticNo Cell WallMobile

Mammals, insects, birds, reptiles, sponges, worms

TaxonomyClassification and naming of organisms7 Taxonomic Groupings from most inclusive to most specific:

KingdomPhylumClassOrderFamily GenusSpecies

“Kings play chess on fine green silk”

Linnean TaxonomyCarolus Linnaeus (1707-1778)

Binomial nomenclature (2 name naming)Genus and species to make the scientific nameProvides a common name that can be used by all biologists regardless of their native language.

Example: human vs. chimpanzeeKingdom animalia animaliaPhylum chordata chordata Class mammalia mammaliaOrder primata primataFamily hominidaehominidaeGenus homo panSpecies sapienstroglodytes

Homo sapiens and Pan troglodytesClassification activity

Linnean Taxonomy

The Origin of LifeGeologyThe Fossil RecordComparative EmbryologyComparative BiochemistryComparative AnatomyIsn’t Evolution Just a Theory?

Scientists from many disciplines including biology, chemistry, physics, geology, and paleontology have contributed to the case for evolution!

The Origin of LifeOrigin of the UniverseBig Bang

Early EarthEvolution Starts Up: Chemical EvolutionHeterotroph Hypothesis: Molecules of life arose from inorganic building blocks

The Miller-Urey ExperimentStudied Molecules Present at Time of Early Earth

Methane, Ammonia, Carbon Dioxide, Water VaporMixed Molecules in Reaction ChamberSparked with Electricity to Simulate LightningExposed Mixture to UV Radiation to Simulate Cosmic RaysProduced Basic Amino Acids and Organic Molecules

Miller-Urey Apparatus

Biological EvolutionRNA as a information molecule and catalystEndosymbiotic Theory

Mitochondria and chloroplasts were originally free living prokaryotic cellsBoth have own DNA and ribosomesJoined together to cooperate

GeologyThe Study of the Earth and RocksEarly Ideas About Earth:

People believed Earth was only a few thousand years oldPeople believed that rocks and geological features were shaped by catastrophic events and rarely changed

GeologyIn the 18th and 19th Century Scientists Studied Geology in Great Detail

Old Earth, Ancient Life: Georges-Louis Leclerc, Comte de Buffon

Charles Lyell: The Principles of Geology

Earth is Changed by Weather and Natural Processes like Volcanoes and ErosionTakes a Very Long Time!Gradualism and Uniformitarrianism

Continental DriftOver millions of years 1 original continent Pangea drifted apart to make our modern continentsContinental drift is gradual “gradualism”

Sea Floor Spreading

Plate Tectonics

GeologyThese ideas refute the idea that the Earth is only a few thousand years oldProvides long time necessary for evolution

Backed up by radiometric dating The Earth is approximately 4.6 Billion Years Old

4,600,000,000 years is a long time!

Direct Evidence of Evolution

The Fossil RecordFossils are the preserved remains of ancient organisms

Provide information about past organismsShows that many diverse organisms lived at different times in Earth’s History

Preserved remains or traces of ancient organisms

Examples:

The Fossil The Fossil RecordRecordProvide a record of past species

Important source of information for determining ancestry and patterns of evolution

Fossil Archaeopteryx

What does the fossil record tell us?

http://www.pbs.org/wgbh/evolution/library/04/3/quicktime/l_043_01.html

•What past life looked like

•What past habitats were like and changes that have occurred

•That diverse organisms lived on earth at different times

•New species evolved

•Some species became extinct

•Earliest life forms were aquatic

•Earliest life forms were simple in structure

Missing Link?

The Fossil RecordTaphonomy: The Formation of Fossils

Fossils form in sedimentary rockDead organisms covered by sand and siltSediments are passed into bone by pressure from above (fossils form in sedimentary rock)Video

Determining the Age of FossilsRelative Dating: Technique used by scientists to determine the age of fossils relative to fossils in other layers of rock

Different layers represent different geologic periods Older fossils found in lower layers, newer fossils found in upper layersCannot determine the actual age of the fossil!

Determining the Age of FossilsRadioactive Dating: Process by which traces of radioactive elements are analyzed to calculate the actual age of a fossilMany radioactive elements can be used as geologic clocks. Each radioactive element decays at its own nearly constant rate. Once this rate is known, geologists can estimate the length of time over which decay has been occurring by measuring the amount of radioactive parent element and the amount of stable daughter elements Video

Radioactive/Radiometric Dating

How it Works:- radioactive elements (uranium,

Carbon14) break down/decay a specific rates = half life

- these rates are nearly constant

- the amount of radioactive decay that has taken place in a rock/fossil determines its age

Scientist Measure the Age of the EarthRadiometric Dating: way of estimating the age of

the Earth!

http://www.pbs.org/wgbh/evolution/library/03/3/quicktime/l_033_01.html

Carbon-14 Dating

- Determines the age of fossils of a biological origin up to approx. 50,000 years old.

- used in dating things such as bone, cloth, wood, plant fibers, etc.

5,700 year is C14 half-life

Half-life of carbon-14 is 5730 years

Half-life of carbon-14 is 5730 years

22,920 11,460

28,650 17,190

Radiometric DatingRadioactive Parent

Stable Daughter

Half life

Potassium 40 Argon 40 1.25 billion

yrs

Rubidium 87Strontium

8748.8 billion

yrs

Thorium 232 Lead 20814 billion

years

Uranium 235 Lead 207704 million

years

Uranium 238 Lead 2064.47 billion

years

Carbon 14 Nitrogen 14 5730 years

The Geologic Time ScaleBased on fossil and geologic evidenceA record of the Earth’s pastDivided into Era, Period, and EpochShows that life on Earth followed geologic change on Earth

Deep Time ActivityInteractive Time Scale

Comparative EmbryologyEmbryos are organisms at early stages of development

Comparative EmbryologyAll vertebrate embryos, including humans, share features

Eye spot • (Evolution of the Human Eye)

Gill pouchesNotochord

Shows similar genetic ancestryVideo

Comparative BiochemistryAll life is based on organic chemistry

Carbon based compounds

All life uses same molecule as blueprint DNA

Similar chemical processesBacteria, algae, and plants all do photosynthesis

Similar organisms have similar genetic codeHumans and chimpanzees share nearly identical genes (98.4% identical gene sequences) Video

Anatomy and Comparative AnatomyVestigial Organs

Organs inherited but not used by modern organismsPresent but greatly reduced in modern organismsHip bone in pythonAppendix in humanTail bone (cocyx) in human

Anatomy: Homologous StructuresSimilar parts of different organisms, often quite dissimilar in purpose, that developed from the same ancestral body parts (Video)Divergent evolution

Anatomy: Analogous StructuresSimilar in purpose, but not inherited from a recent common ancestorEnvironment selected for trait

Wings of birds and insects

Convergent evolution

Summary

There is overwhelming evidence to support the Theory of EvolutionEvidence comes from disciplines as varied as biology, geology, chemistry, physics, astronomy, and paleontologyEvolution has produced the great beauty and diversity of life on Earth over the last 4 billion years

Human Evolution

Explore Human EvolutionView the Becoming Human broadband documentary

As you view each segment, visit the related exhibits to further explore this topic

Go to the Learning Center and select the “Calculating Cousins” activityGo to the Learning Center and select the “Chromosome Connection” activityGo to the Learning Center and select the “Building Bodies” activity

The Order Primate

Characteristics of PrimatesStrong hands and opposable thumbsFree-moving shoulder jointForward facing eyes and stereoscopic visionIntelligence/larger brainSocial complexity

What Characteristics do Humans Have?All of those of primates, plus

Upright posture and bipedalUse of tools and technologyAdvanced intelligenceComplex communication and speech

The Steps to Human Evolution

TerrestrializationBipedal (Walking on all two’s)Increased Brain SizeCivilizationTake a look at the Human family tree

The Hominid Family

Each year new fossils are found to add to the Hominid family treeMost fossils of early humans are found in Africa and lower AsiaMost well understood members include genus Australopithecus (extinct) and genus HomoSolve the Riddle of the Bones

Genus AustralopithecusFirst human ancestor to live on the ground and walk on two legs

As evidenced by the Laetoli footprints

Ape-like jawSmall brainShort statureFound only in South and East Africa

The AustralopithecinesA. anamesis 4 MYAA. afarensis 3.2 MYA (Finding “Lucy”)A. africanus 2.5 MYAA. robustus 2 MYA A. boisei 2 MYA

Genus HomoMore modern hominids that exhibited major evolutionary steps

Increased brain sizeUse of toolsUse of fireUse of shelterReligionLanguage and civilization

Homo habilis “The Tool Man”Approx. 2.5 MYABrain ½ size of modern humanFirst to make and use stone tools and weapons

Homo erectus “The Upright Man”

Direct ancestor of modern humansWidespread in Africa and Asia by 1 MYAEvidence of use of shelter and fire

Homo sapiens “The Wise Man”Most likely evolved from H. erectus as early as 400,000 years agoGreatly increased brain sizeConsisted of 2 groups

NeanderthalCro-Magnon/modern H. sapiens

NeanderthalsFound in Neander Valley in GermanyFossils found throughout Europe, Middle East, and Asia from 150,000-30,000 years agoLarge bodies and brainsEvidenced painting, religion, complex social structure“Cave man”

Cro Magnons and Fully Modern HumansFirst early modern H. sapiens appear about 130,000 years agoThinner bones, smaller jaws, higher skull with little or no brow ridge, and larger brainsCave art shows complex religion and cultureLived alongside Neanderthal for several thousand years, but eventually out-competed them

Education

Evolution natural selection_and_speciation 6 kings