Evolution

http://www.pbs.org/wgbh/evolution/educators/teachstuds/svideos.html - video 7Evolution and Adaptation Notes**** Dont talk about Lamarck specifically just who influenced Darwin, and not specific relative and radioactive dating just broad of this is how you can tell how old fossils are****Do talk about gene flow, genetic drift, recombination (sexual reproduction and crossing over), and mutation, convergent and divergent evolution ADD the stabilizing, directional and disruptive selection and add cladograms introductionGood flow: Darwin and who influenced him then Evolution with natural selection then Evolution of populations (divergent vs convergent and include genetic drift, etc) then the Evidence of Evolution then the time gradualism and punctuated equilibrium

Performance task use the homer simpson video and see what 5 misconceptions are and suggest alternatives: http://www.youtube.com/watch?v=faRlFsYmkeY

1What is Evolution??

EvolutionEvolution - Change in a kind of organism over time; process by which modern organisms have descended from ancient organisms.

What is a Theory versus a Hypothesis?https://www.youtube.com/watch?v=85diEXbJBIk - video 1

Hypothesis TheoryAn educated guess that has to be testable by scientific methodsHas to be well-supported and has been tested over and over Is an explanation of a phenomena that has occurred in the natural world.

Origins of Evolutionary Thought1785 - James Hutton: Proposes that earth is shaped by geological forces that took place over extremely long periods of time (gradualism). He estimates Earth to be millions not thousands of years old.1798 Thomas Malthus: Predicts that the human population will grow faster than the space and food supplies needed to sustain it.

Origins of Evolutionary Thought1809 Jean-Baptiste Lamarck: Proposed that changes in environment caused an organism to have greater use or disuse of a structure/organ. His ideas are flawed, but he is one of the first to propose a new mechanism explaining how organisms change over time (inheritance of acquired traits). 1833 Charles Lyell: Observed processes that made small changes in Earths features are uniform through time and have shaped Earths geological features over long periods of time.

Charles DarwinDuring Darwins trip around the world he noticed all the variation (different physical traits of an individual in the group it belongs) of traits among similar species.

Charles Darwin - The Galpagos IslandsGiant tortoises & Finches varied according to the island each inhabited. These species were able to adapt with adaptations ( a feature that allows an organism to better survive and reproduce in its environment) to their surroundings.

Charles Darwin- insight leading to natural selectionDarwin noticed lots of variation of species in nature and on farms. Saw breeders were selecting only the largest hogs, the fastest horses, or the cows that produced the most milk and breeding those with each other. Darwin termed this process artificial selection.Artificial selection When humans select those variations provided by nature that they found useful/beneficial.

Charles Darwin- insight leading to natural selection Darwin used all prior scientist knowledge along with his own findings and proposed a mechanism for evolution called natural selection.

Darwins ConclusionsEvolution Occurs by Natural SelectionStruggle for survival exists in nature Competition among members of a species exist for food, living space, and the other necessities of life.

Survival of the Fittest Individuals that are better suited to their environment that it, with adaptations that enable fitness survive and reproduce more successfully; Darwin referred to this as natural selectionFitness - Ability of an organism to survive and reproduce relative to other members of the population in its environment.

http://www.pbs.org/wgbh/evolution/educators/teachstuds/svideos.html - video 4

12Darwins ConclusionsEvolution Occurs by Natural Selection2. AdaptationCertain variations allow individuals to adapt and survive better in their environment. Those more successful will live longer and share those adaptations to future generations.Natural selection cannot be seen directly; it can only be observed as changes in a population over many successive generations.

http://www.pbs.org/wgbh/evolution/educators/teachstuds/svideos.html - video 613AdaptationsAdaptation Inherited characteristic that increases an organisms chance of survival.Can be either physical or behavioral.Animals have evolved their adaptations.A long period of slow change resulted in an animals adaptations.Example: The spots on the snow leopard did not emerge overnight. Instead, this process took generation upon generation of snow leopards physically adapting to their environment for characteristic spot patterns to evolve. Those leopards with spot patterns were able to hide more successfully, therefore surviving longer than those without spots. This allowed the longer surviving snow leopards to reproduce and create more snow leopards with spot patterns like their own.This process of change over time is the key to how many organisms develop adaptations.Some adaptations can arise quickly through genetic mutations as well. But some mutations can be deadly as well.

Darwins ConclusionsEvolution Occurs by Natural Selection3. Decent with ModificationDarwin proposed that over long periods, natural selection produces organisms have different structures, establish different niches, or occupy different habitats = species today look different from their ancestors.Each living species has descended, with changes, from other species over time.Darwin referred to this principle as descent with modification

Talk about why we have wrinkled fingershttp://phenomena.nationalgeographic.com/2013/01/11/debate-did-wrinkled-fingers-evolve-for-better-grip/15Darwins ConclusionsEvolution Occurs by Natural Selection4. VariationMany genes have at least two genes or alleles. Animals such as dogs, horses, and mice often have several alleles for traits such as body size or coat color. All organisms have additional genetic variation that is invisible because it involves small differences in biochemical processes. An organism can be heterozygous for many genes.

Evidence of Evolution comes primarily from these sources.http://www.pbs.org/wgbh/evolution/educators/teachstuds/svideos.html - video 3Fossil record Geographical distribution of living speciesStructural similarities of related life formsChemical similarities in DNAEmbryology

Evidence of Evolution: Fossil RecordFossils are direct or indirect remnants of the past.The fossil record provides evidence about the history of life on Earth. It also shows how different groups of organisms, including species, have changed over time, that life on Earth has changed.The fossil record is not complete- there are gaps but they are being filled as we speak!!! 99% of living species are now extinct

Fossil record of horses

In 1974 remains of this skeleton were found in Ethiopia and lived 3-3.9 million yrs ago. She was 3 ft. 8 in tall and weighed ~65 lbs. Because of her pelvis she was one of the first to show upright walking. She has a really small skull but front teeth like a human.

Lucys baby in 2006 they found the oldest earliest child fossil in Ethiopia about 3 yrs old, female, skull, milk teeth, tiny fingers, torso, foot and kneecap (no bigger than a dried pea) more complete than Lucy and 120,000thousands of years older even.

In 1974 remains of this skeleton were found in Ethiopia and lived 3-3.9 million yrs ago. She was 3 ft. 8 in tall weighed ~65 lbs, bc of her pelvis she was one of the first to show upright walking, she has a really small skull but front teeth like a human

Lucys baby in 2006 they found the oldest earliest child fossil in Ethiopia about 3 yrs old, female, skull, milk teeth, tiny fingers, torso, foot and kneecap (no bigger than a dried pea) more complete than Lucy and thousands of yrs older even19Age of FossilsPaleontologists determine the age of fossils using two techniques: Relative dating Radioactive datingRadioactive Dating

Relative DatingRelative DatingIn relative dating, the age of a fossil is determined by comparing its placement with that of fossils in other layers of rock. Paleontologists estimate the age based on the age of other fossils found near it. Its not absolute and doesnt tell the age in years..The rock layers form in order by age:The oldest layers on the bottomMore recent layers on top (closer to Earth's surface)

Radioactive DatingScientists use radioactive decay to assign absolute ages to rocks. Some elements (C, K, Ar) found in rocks are radioactive.Radioactive elements decay, or break down, into nonradioactive elements at a steady rate, which is measured in a unit called a half-life. In radioactive dating, scientists calculate the age of a sample based on the amount of remaining radioactive isotopes it contains.

Radioactive DecayA half-life is the length of time required for half of the radioactive atoms in a sample to decay. After 1 half-life - Half of the original radioactive atoms in a sample have decayed. Of those remaining atoms, half again are decayed after another half-life.

Evidence of Evolution: BiogeographySimilar, but unrelated species exist. Similar animals in different locations were the product of different lines of evolutionary descent.Some animals on each continent live under similar ecological conditions.Are exposed to similar pressures of natural selection.Because of these similar selection pressures, different animals ended up evolving certain striking features in common.

Evidence of Evolution: Structural Similarities of Living ThingsHomologous StructuresAnalogous StructuresVestigial Structures

Homologous Structures of Living OrganismsResearchers had noticed striking anatomical similarities among the body parts of animals with backbones. Example: The arms of reptiles, wings of birds, and legs of mammals vary greatly in form and function. Yet, they are all constructed from the same basic bones.

Homologous StructuresHomologous Structures - Structures that have different mature forms in different organisms but develop from the same embryonic tissues.Same development - different function.Provide strong evidence that all four-limbed vertebrates have descended, with modifications, from common ancestors.

Analogous StructuresAnalogous Structures - Structures that evolve separately to perform a similar function.Different development same function.Provides evidence for convergent evolution because they have very similar structures even though they were completely independently derived to fill a similar purpose.Examples: Wings of birds, bats, and insects (have different embryological origins but are all designed for flight).

Vestigial OrgansVestigial Organs Organ that serves no useful function in an organism; Traces of homologous structures. Examples: Hip bones found in whales, salamanders, and pythons Eye bulbs of blind, cave-dwelling creatures, such as the grotto salamander.Human coccyx bone (tail bone) lost original function of a tail but now serves as places for bones to attach

A surgeon can remove an appendix from someone, and there doesn't seem to be any noticeable effect, but a healthy appendix is beneficial (acts as a filter and removes bacteria and protects the intestines from infection. Antibodies are also made there). Appendix used to help digest cellulose when we were herbivores but not anymoreCoccyx remnants of tail lost original function of tail but serves now for places bones to attachWisdom teeth

29Evidence of Evolution: Chemical SimilaritiesAll of the tens of thousands of types of proteins in living things are made of only 20 kinds of amino acids. Despite the great diversity of life on our planet, the simple language of the DNA code is the same for all living things. This is evidence of the fundamental molecular unity of life.New technologies, such as DNA fingerprinting, have helped to fill in gaps in the fossil record.

Amino Acid Comparisonhttp://www.pbs.org/wgbh/evolution/educators/teachstuds/svideos.html - video 5The more closely related two species are, the more amino acid sequence similarities should be seen.

A B C D E F G HTry to guess which embryo is the:Chicken?Rabbit?Fish?Human?

Evidence of Evolution: Similarities in EmbryologyThe early stages, or embryos, of many animals with backbones are very similar. Many embryos look especially similar during early stages of development.The same groups of embryonic cells develop in the same order and in similar patterns to produce the tissues and organs of all vertebrates.

EVOLUTION OF POPULATIONSHow does a population of penguins evolve??

Variation increases chance of survivalGenetic variation is studied in populations.A population is a group of individuals of the same species that interbreed. Because members of a population interbreed, they share a common group of genes called a gene pool. Gene Pool - Consists of all genes, including all the different alleles, that are present in a population.

Sources of Genetic VariationThe two main sources of genetic variation are:Mutations Any change in a sequence of DNA. Can occur because of mistakes in the replication of DNA or as a result of radiation or chemicals in the environment.Recombination - The natural formation in offspring of genetic combinations not present in parents.Independent assortment occurs during the production of gametes each homologous pair moves independently during meiosis. Crossing over during meiosis further increases variation.

Natural Selection acts on distribution of traitsNatural selection can affect the distributions of phenotypes in any of three ways:Directional SelectionStabilizing SelectionDisruptive Selection

Directional SelectionDirectional Selection Takes place when individuals at one end of the curve have higher fitness than individuals in the middle or at the other end. The range of phenotypes shift as some individuals fail to survive and reproduce while others succeed. Ex drug resistant bacteria

Stabilizing SelectionStabilizing Selection Takes place when individuals near the center of the curve have higher fitness than individuals at either end of the curve.This situation keeps the center of the curve at its current position, but it narrows the overall graph.Example: The weight of human infants smaller than average babies are likely to be less healthy and larger than average babies are likely to have difficulty being born.

Disruptive SelectionDisruptive Selection Takes place when individuals at the upper and lower ends of the curve have higher fitness than individuals near the middle. In such situations, selection acts most strongly against individuals of an intermediate type. If the pressure of natural selection is strong enough and lasts long enough, this situation can cause the single curve to split into two (can create two distinct phenotypes).

Other Mechanism for Evolution besides natural selectionGene Flow - The movement of alleles (genes) from one population to another.Affected by:MobilityBarriers Environment (wind)

Other Mechanism for Evolution besides natural selectionGenetic Drift - Random change in allele frequencies that occurs in small populations due to chance.Unlike natural selection because:It happens by chance caused by big event like overhunting or a natural disaster (fire, landslide or lightning strike).Doesnt work to produce adaptations like natural selection does.

How Does Genetic Drift Occur?In each generation, some individuals may, just by chance, leave behind a few more descendants (and genes, of course) than other individuals. The genes of the next generation will be the genes of the lucky individuals, not necessarily the healthier or better individuals. It happens to all populations theres no avoiding the vagaries of chance.

Evolution vs. Genetic EquilibriumTo clarify how evolutionary change operates, scientists often find it helpful to determine what happens when no change takes place.So biologists ask: Are there any conditions under which evolution will not occur? The Hardy-Weinberg Principle Hardy Weinberg Equation: p2 + 2pq + q2 = 1 p + q = 1

Hardy-Weinberg PrincipleFive conditions are required to maintain genetic equilibrium from generation to generation: There must be random mating.All members of the population must have an equal opportunity to produce offspring, which ensures that each individual has an equal chance of passing on its alleles to offspring.The population must be very large.Genetic drift has less effect on large populations than on small ones. There can be no movement into or out of the population.Individuals may bring new alleles into a population.There can be no mutations.If genes mutate from one form into another, new alleles may be introduced into the population, and allele frequencies will change.There can be no natural selection. No phenotype can have a selective advantage over another.

The Hardy-Weinberg Equation For example: If the frequency of two alleles in a gene pool is 90% A , and 10% a, what is the frequency of individuals in the population with the genotype Aa?Solve: p = frequency of A, which is .9 (90%) q = frequency of a, which is .1 (10%) 2pq = frequency of Aa = 2(.9)(.1) = .18 Therefore, the frequency of individuals with genotype Aa would be .18

p2 = Frequency of AA2pq = Frequency of Aaq2 = Frequency of aap = Frequency of Aq = Frequency of a

The Process of SpeciationHow do these changes from natural selection or chance lead to the formation of new species, or speciation?Species - Group of organisms that breed with one another and produce fertile offspring

Speciation & Reproductive IsolationThe gene pools of two populations must become separated for them to become new species. As new species evolve, populations become reproductively isolated from each other. Reproductive Isolation - When the members of two populations cannot interbreed and produce fertile offspring.

Reproductive IsolationReproductive isolation occurs when members of different populations can no longer mate successfully.Behavioral IsolationGeographic IsolationTemporal Isolation

Behavioral IsolationBehavioral Isolation - Two populations are capable of interbreeding but have differences in courtship rituals or other reproductive strategies that involve behavior.Example: Eastern and Western Meadowlarks Members of the two species will not mate with each other partly because they use different songs to attract mates. Eastern meadowlarks will not respond to western meadowlark songs, and vice versa.Geographic IsolationWith geographic isolation, two populations are separated by geographic barriers such as rivers, mountains, or bodies of water.Example: The Abert & Kaibab SquirrelAbout 10,000 years ago, the Colorado River split the species into two separate populations. Two separate gene pools formed. Natural selection worked separately on each group and led to the formation of a distinct subspecies, the Kaibab squirrel.

Temporal IsolationTemporal Isolation - Form of reproductive isolation in which two populations reproduce at different times.Example: Three similar species of orchid all live in the same rain forest. Each species releases pollen only on a single day. Because the three species release pollen on different days, they cannot pollinate one another.

Patterns of EvolutionSome large-scale evolutionary patterns and processes that occur over long periods of time are:ExtinctionConvergent EvolutionDivergent EvolutionGradualismPunctuated Equilibrium CoevolutionExtinctionMore than 99% of all species that have ever lived are extinct. Extinctions happen because species compete for resources, and environments change. Some species adapt and change. Others gradually become extinct in ways that are often caused by natural selection.Each disappearance of species left habitats open and provided ecological opportunities for those organisms that survived. The result is often the burst of evolution that produces many new species. The extinction of the dinosaurs cleared the way for the evolution of modern mammals and birds.

Convergent EvolutionConvergent Evolution Process by which unrelated organisms come to resemble one another. (analogous structures)Examples: Natural selection may mold different body structures, such as arms and legs, into modified forms, such as wings or flippers. The wings or flippers function in the same way and look very similar. The similar nature of the wings of insects, birds, pterosaurs, and bats. All four serve the same function and are similar in structure, but each evolved independently and not from a common winged ancestor.

Divergent EvolutionDivergent Evolution The process of two or more related species becoming more and more dissimilar. (homolougous structures)A single species or a small group of species have evolved, through natural selection and other processes, into diverse forms that live in different ways. The vertebrate limb is one example of divergent evolution. The limb in many different species has a common origin, but has diverged somewhat in overall structure and function

Gradualism vs. Punctuated EquilibriumHow quickly does evolution occur?Gradualism Long time with gradual change.Punctuated Equilibrium - Long, stable periods interrupted by brief periods of more rapid change.

Gradualism example Punctuated equilibrium example - 59Think about thisHow did a tiger get its stripes? Gradually or with a huge, quick change?

http://www.necsi.edu/projects/evolution/evolution/grad+punct/evolution_grad+punct.html60CoevolutionCoevolution the process in which two or more species evolve in response to changes in each other.

Common MisconceptionsHumans did not come from monkeys. Instead, humans and primates share a common ancestor.Darwin is not the only evolutionary theorist. Darwin utilized evidence from other evolutionists to draw his conclusions.Evolution does not happen quickly it occurs over generations of time.Change does not occur at the individual level it occurs in populations.

CladogramCladogram Diagram that shows the evolutionary relationships among a group of organisms.Is constructed using derived characters, which are characteristics that appear in recent parts of a lineage but not in older members.

PhylogenyPhylogeny - Study of evolutionary relationships among organisms. Biologists now group organisms into categories that represent lines of evolutionary descent, or phylogeny, not just physical similarities.

Now watch the Homer Simpson video again..http://www.youtube.com/watch?v=faRlFsYmkeY Why is this cartoon inaccurate? Use the information that youve learned about evolution in this unit!Adaptions Catepillar that looks like a snake