Evolution

Mrs. ChavarriaEvolutionQuick Review: Theory vs. LawTheory: A well-tested explanation to make accurate predictionsThey can be changed!Law: A generalized way of explaining things, but doesnt necessarily say whyLaw of gravityCant be disproven

Earths Early History 19.3What do scientists hypothesize about early Earth and the origin of life?What theory explains the origin of eukaryotic cells?What is the evolutionary significance of sexual reproduction?

The Mysteries of Lifes OriginsEarth was struck by a large object and heatedEventually cooled down enough to form oceansIts atmosphere had very little oxygen

The Mysteries of Lifes OriginsMiller and Ureys experiment suggested how mixtures of organic compounds necessary for life could have arisenNot entirely accurate more recent experiments have been doneFirst formations were thought to be proteinoid microspheres that had some characteristics of living things NOT CELLS!

The Mysteries of Lifes OriginsRNA World hypothesis states that RNA came before DNA do you think this is possible?

The Mysteries of Lifes OriginsFirst forms of live evolved to live in an oxygen free world anaerobic prokaryotesEventually, photosynthetic bacteria came around which produced _________. This allowed aerobic organisms to evolve.

Origin of Eukaryotic CellsEukaryoticProkaryoticHave nucleusHave membrane-bound organellesHave mitochondriaNo nucleusVery few membrane-bound organelles

Origin of Eukaryotic CellsThe endosymbiosis theory suggests that a __________ relationship evolved between eukaryotes and prokaryotesCreated the mitochondria and the chloroplasts we know today

Origin of Eukaryotic CellsIn support of this hypothesis:Mitochondria and chloroplasts contain their own DNA which is similar to bacteria DNA.Have their own ribosomesReplicate like bacteria (binary fission)

Sexual ReproductionImportant in our evolutionary history because it introduces genetic diversity / variation.Genetic variation increases the likelihood of a population adapting to new or changing environmental conditions.

Evidence of Evolution 16.4How does the geographic distribution of species today relate to their evolutionary history?How do fossils help to document the descent of modern species from ancient ancestors?What do homologous structures and similarities in embryonic development suggest about the process of evolutionary change?How can molecular biology be used to trace the process of evolution?What does recent research on the Galapagos finches show about natural selection?

Evidence of EvolutionDarwin hypothesized that animals evolved because of natural selection what is that??

BiogeographyPatterns in the distribution of living and fossil species tell us how modern organisms evolved from their ancestors.

BiogeographyClosely related but differentDistantly related but similarAlike species with different traits Different species with same traits (similar environment)

Age of Earth & FossilsRadioactive data shows Earth to be 4.5 billion years old supporting Darwins theory (lots of time for evolution)Recent fossil records are filling the gaps, showing that modern species evolved from extinct ancestors.

Comparing Anatomy & EmbryologyEvolutionary theory explains the existence of homologous structures adapted to different purposes as the result of descent with modification from a common ancestor.

Comparing Anatomy & PhysiologyHomologousAnalogousSimilar structureSimilar function

Comparing Anatomy & EmbryologyVestigial structures arent necessary, but dont harm the function of the organism and so they remainAppendix!

Comparing Anatomy & EmbryologySimilar patterns of embryological development provide further evidence that organisms have descended from a common ancestor.

Genetics & Molecular BiologyAt the molecular level, the universal genetic code and homologous molecules provide evidence of common descentMost of the DNA and RNA used from bacteria to humans is the same. We must have come from a common ancestor!

Genetics & Molecular BiologyHomologous proteins are shared from bacteria to humans how we make insulin from bacteria for our use.Homologous genes exist between flies and humans these same genes direct our head-to-tail development and limbs

Testing Natural SelectionThe Grants were able to test Darwins hypothesis by:Analyze that there was enough heritable variation in the traits for natural selectionThere were enough differences in beak size and shape to produce differences in fitness

Testing Natural SelectionDry weather = more survival of large beak birdsTheir data confirmed that competition and environment drive natural selection

Hominine Evolution 26.3 (Pg. 767)What adaptations enabled later hominine species to walk upright?What is the current scientific thinking about the genus Homo?

Hominine EvolutionWe separated to create hominines and chimpanzeesThe skull, neck, spinal column, hip bones, and leg bones of early hominine species changed shape in ways that enabled later species to walk upright bipedal.

Hominine EvolutionBipedal allowed us to free our hands for tools developed opposable thumbsAlso developed larger brains (cerebrums)Figure 26-16 gives major differences between humans and gorrillas

Hominine EvolutionFossils date back to 7 million years old not all findings are ancestors, they may be relativesResearch suggests bipedalism evolved before larger brainsOldest hominine: 2002, SahelanthropusBest studied:1974, Australopithecus afarensis or Lucy

Hominine EvolutionRecent research shows our human evolution isnt straight forward more like several branches and several trunksHomo habilis: handy man, probably our ancestorHomo ergaster: bigger brain, downward-facing nostrils

Hominine EvolutionOur genus originated in Africa and migrated from there to populate the worldHomo habilis in TurkeyHomo Erectus in Asia

Hominine EvolutionMultiregional hypothesis says we evolved independently in various parts of the worldOut-of-Africa model suggests we migrated and colonized the rest of the world about 200,000 years ago More supported theory by mitochondrial DNA evidence

Hominine EvolutionModern humans may or may not have coexisted with Neanderthals something made Neanderthals go extinct and Homo sapiens remain the only hominine clade.Both used stone tools, lived in complex social groups, controlled fire, and had rituals to bury their dead.

GO HEAT!!

The Brain (Pg. 902-903)Split into 5 major components:CerebrumLimbic SystemThalamus and HypothalamusCerebellumBrain Stem

The BrainCerebrum: largest region of the brain responsible for voluntary (conscious) activitiesIntelligence, learning and judgment are stored hereThe part that grew the most in our ancestors

The BrainThe Cerebrum is split up into right and left hemispheres Left hemisphere controls right-side of the body and vice versaAlso into four lobesFrontal (planning, judgments)Temporal (hearing and smell)Parietal (reading and speech)Occipital (vision)

The BrainThe Cerebrum also has two layersThe cerebral cortex (topmost layer, aka grey matter) which has many of the neurons responsible for all the activitiesWhite matter (innermost layer) which makes connections between different brain areas

The BrainLimbic System: mostly associated with emotions, behavior, and long-term memory

The BrainThalamus: receives messages from sensory neurons and sends them to the right placeHypothalamus: helps to know and analyze hunger, thirst, fatigue, anger, and body temperature

The BrainCerebellum: second largest region of the brain which deals with coordinating the bodys actions

The BrainBrain stem: the oldest part of the brain which connects the brain to the rest of the bodyAlso controls important functions like blood pressure, heart rate, breathing, and swallowingWhat keeps you breathing while you sleep

Darwins Voyage of Discovery 16.1Darwin developed a scientific theory of biological evolution that explains how modern organisms evolved over long periods of time through descent from common ancestorsDarwin was born in 1809 and began his journey in 1831 on the HMS Beagle

Observations Aboard The BeagleDarwin didnt just observe species, he thought about them in scientific ways and noticedSpecies vary globallySpecies vary locallySpecies vary over timeDifferent species inhabit separate, but ecologically similar habitats

Observations Aboard The BeagleDarwin also noticed that different, yet related animal species occupied different habitats within a local areaAll his observations were conducted between Australia, South America, and Africa (and of course, the Galapagos)

Observations Aboard The BeagleDarwin also noticed that some fossils of extinct animals were similar to living species the Glyptodont and the ArmadilloAll of this evidence suggested that species are not fixed, but that they change by some kind of natural process which we know today as ________________.

Lets Practice!Find your study buddyStudy Workbook A Pgs. 169-170. Question AND Answer. One sheet of paper for both of youSkip #4

Ideas that shaped Darwins thinking 16.2Hutton and Lyell, two geologists, concluded that Earth is extremely old and the processes that changed Earth in the past are still operating in the presentWent against the idea that Earth was only a few thousand years old

An Ancient, Changing EarthHutton introduced deep time: our planets history is older than we can imagine. He reached this conclusion by his observations of:The layers of rocks in mountains, valleys, and even volcanic molten lavaRain, wind, heat and cold take a long time to shape rock

An Ancient, Changing EarthLyell believed in uniformitarianism laws are constant over time (what happens now, happened then)Darwin read Lyells book and observed an earthquake push rock from the sea out if Earth was old, and the same things happened, could life have changed too?

Lamarcks Evolutionary HypothesisLamarck suggested that species decide what part of themselves to use / not use, and these traits were passed on to offspringPublished the year Darwin was born, 1809

Lamarcks Evolutionary HypothesisHe suggested that if we wanted longer legs, we simply had to wish or stretch for them and it would happen acquired characteristicsThen, we passed then on to our children inherited acquired characteristicsCrazy ideas! But he was the first to suggest we changed according to our environment essential for people like Darwin to come up with evidence!

Population GrowthMalthus had suggested that we cant grow unchecked because there wont be enough space for everyone we were limited by war, famine and diseaseDarwin linked this to other organisms and reasoned this must be the reason why only certain individuals survive and reproduce

Artificial SelectionVariations cause some animals to be more productive than others we choose the best and breed those to make sure those variations become permanent.Darwin didnt understand where these variations came from, but he knew this would cause changes in the species

Darwin Presents His Case- 16.3Darwin did not publish his ideas immediately for fear of being ridiculed, until he found out Wallace was about to publish something very similar

Evolution by Natural SelectionThe struggle for existence: more are born than can survive, and must compete for resourcesThose with the best adaptations (body part, color, function or behavior) survive and reproduce have high fitness

Evolution by Natural SelectionNatural selection occurs in any situation in which More individuals are born that can survive (survival of the fittest)There is natural heritable variation (variation and adaptation)There is variable fitness among individuals (survival of the fittest)

Evolution by Natural SelectionNatural selection doesnt make perfect organisms- just good enough to survive in their environmentsIf the environment changes, adaptations can change also so long as its not too fast of a change

Common DescentAs generations progress, we get species evolving into new species descent with modificationThe principle of common descent is that all living and extinct species are descended from ancient common ancestors The tree of life

Lets Practice!Puzzle Competition

Evolution as Genetic Change in Populations 17.2What does the book tell us about pesticide use? Pesticide resistance? How does this change the insect population over many years?

Prior KnowledgeGenotype: what your DNA saysPhenotype: what you see (what your DNA codes for)Allele: alternate forms of a gene (hair color can be red, brown, blonde, black, etc)**Natural selection acts on the phenotype, not the genotype**

Prior KnowledgeDominant: the allele that is stronger the phenotype you seeRecessive: the allele that is weaker can be maskedHeterozygous: different alleles (Bb)Homozygous: same alleles (BB, or bb)

Single Gene vs. Polygenic TraitsSingle-Gene TraitPolygenic TraitA trait controlled by only one geneEx: Hair colorA trait controlled by many genesEx: Height

Confused??Please read 17.1 as background information and review these concepts on your own! If you need help, come and see me before / after school!

How Natural Selection WorksEvolutionary adaptation comes from an increased ability of an individual to pass on their particular genes, or allelesNatural selection on single-gene traits can lead to changes in allele frequencies, and thus, to changes in phenotype frequencies

How Natural Selection WorksNatural selection on polygenic traits can affect the relative fitness of phenotypes and thereby produce one of three types of selectionDirectional selectionStabilizing selectionDisruptive selection

Directional SelectionIndividuals at one extreme of the curve have higher fitness than individuals in the middle or other endEx: Big beak birds survived and overtook the population in our Gizmo during drought at the end of the 5 years, all birds were big beak!

Stabilizing SelectionIndividuals at the center of the curve have higher fitness than individuals at either endEx: During normal rainfall, middle size beaked birds survived most in our Gizmo

Disruptive SelectionIndividuals at both ends of the curve have higher fitness than individuals in the middleEx: If only very small and very large seeds are left, birds with small and large beaks will be the only ones left almost creates two different species

Directional, Stabilizing, Disruptive

Lets Practice!Study Workbook A Pgs. 182-183You may work with a buddy to find the answers

Genetic DriftIn small populations, individuals that carry a particular allele may leave more descendants than other individuals leave, just by chance. We know this random change in allele frequency to be genetic drift

Genetic DriftBottleneck effect: a dramatic change (usually due to a disaster) that leaves very few individuals behind with little genetic diversityEx: Disease

Genetic DriftFounder effect: a small population with limited allele frequencies migrates to a new habitat

Evolution vs. Genetic EquilibriumIf the individuals are not evolving, then the allele frequencies are not changingSexual reproduction may reshuffle genes, but wont introduce anything new

Evolution vs. Genetic EquilibriumThe Hardy-Weinberg principle predicts that 5 conditions can disturb genetic equilibrium and cause evolution:1. Nonrandom mating2. Small population size3. Immigration / Emigration4. Mutations5. Natural Selection

Evolution vs. Genetic EquilibriumNonrandom Mating: if the individual is choosing a mate based on sexual selection (size, strength, or color) then there will be evolutionSmall Populations: Founders effect and Bottleneck effectsImmigration / Emigration: introduces new alleles into the gene poolMutations: also introduces new allelesNatural Selection: favors different phenotypes, and therefore, genes

Lets Practice!Concept Map

The Process of Speciation 17.3Different circumstances can lead to speciation:Reproductive isolation either through behavioral, geographic, or temporal separation

Isolating MechanismsBehavioral isolation typically happens because courtship rituals are differentEx: Birds with different mating calls

Isolating MechanismsGeographic isolation occurs when a natural disaster or landmark separates two species such as mountains or rivers

Isolating MechanismsTemporal isolation occurs when two species reproduce at different times

Speciation in Darwins FinchesSpeciation in Galapagos finches occurred by founding of a new population, geographic isolation, changes in the new population's gene pool, behavioral isolation, and ecological competition

Lets Practice!Study Workbook A Pgs. 184-185Individual Work