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Wednesday: February 22nd 1.) Class will divide into four groups. ALL four groups will read BOTH articles. However, Groups 1 & 2 will be responsible for leading the group discussion with the article: Adaptation: The Case of Penguins” and sharing the answers to this article’s questions. While Groups 3 &4 will be responsible for leading the group discussion with the article: Darwin and Natural Selection” and sharing the answers to this article’s questions. (Please do not write on the articles, write on loose leaf paper. All responses to questions must be submitted before the end of class. Therefore, please pay close attention when your peers are sharing article responses!) 2.) Continue with Evolution PowerPoint & Packet! Ms. Fisher 2/22/12

Wednesday: February 22nd

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Ms. Fisher 2/22/12. Wednesday: February 22nd. 1.) Class will divide into four groups. ALL four groups will read BOTH articles. However, Groups 1 & 2 will be responsible for leading the group discussion with the article: - PowerPoint PPT Presentation

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Evolution Presentation for Biology Keystone

Wednesday: February 22nd1.) Class will divide into four groups. ALL four groups will read BOTH articles. However, Groups 1 & 2 will be responsible for leading the group discussion with the article: Adaptation: The Case of Penguins and sharing the answers to this articles questions. While Groups 3 &4 will be responsible for leading the group discussion with the article: Darwin and Natural Selection and sharing the answers to this articles questions. (Please do not write on the articles, write on loose leaf paper. All responses to questions must be submitted before the end of class. Therefore, please pay close attention when your peers are sharing article responses!)2.) Continue with Evolution PowerPoint & Packet!

Ms. Fisher 2/22/12Objective for today:Through reading different articles on adaptation and natural selection with your peers, you will further develop your understanding on natural selection and know what factors play a role in this process. Today, you will complete and submit corresponding worksheets that go with these articles. (If time allows, continue with evolution power-point.)

Human embryo5 weeks afterconceptionEvidence For Evolution:V. EmbryologyEmbryology

Very close similarities in early developmental stages of related species

1 cm

DNA

Genetic code shared by all living things on EarthAllows us to look at different species at the molecular level and compare their genes.Shows conclusively that all living things are related; its just a matter of degree.Evidence For Evolution:VI. DNA and GeneticsOther human examples include the tailbone and wisdom teeth.Evidence For Evolution:III. Vestigial StructuresHuman Examples

Remnant of earlier primate ancestors with tailsLeftover from our ancestors with larger jawsThis is why wisdom teeth are so commonly removed. Modern humans jaws tend to be too small, so the teeth get impacted. Some people never even develop wisdom teeth.Chromosomal Evidence

HumanChimpOrangutanGorillaThis is extremely conclusive evidence of our common ancestry with all the other apes.Click the image above to see biology professor Kenneth Miller explain the Case of the Missing Chromosome.

Evidence For Evolution:VI. DNA and GeneticsSection 4 of 4: Evolution in Action1) What is Evolution?2) Natural Selection 3) Evidence for Evolution4) Evolution in ActionEvidence For Evolution:III. Vestigial StructuresOther Vestigiality

Rather than physical structures, some vestigial traits come in the form of reactions or behaviors.

When you get goosebumps because you are startled or get a chill, your body is reacting in the same way as this cat.This reaction no longer serves any purpose in human beings but earlier mammal ancestors, as well as those still around, use it to puff up their fur for warmth, or to intimidate would-be predators.Similar to whales, pythons and boa constrictors have remnants of pelvic bones and legs. In this case, however, they are actually visible externally.

Certain fish species which have lived in caves for thousands of years have evolved to have no eyes, since they are useless in the dark.

Evidence For Evolution:III. Vestigial StructuresOther VestigialityHere are a couple more examples:

Blind cave fishPelvic spurs on a python

Evidence For Evolution:III. Vestigial StructuresVestigial DNAEven more tellingly, most species, including humans have huge sections of so-called junk DNA which seem to be completely non-functional.Much of this useless genetic material is vestigial. In other words, it used to code for important traits in our ancestors, but is no longer needed.

This vestigial DNA has essentially become deactivated through genetic mutations over the course of millions of years, and is now just taking up space on the genome.Assessment:Objective for Today:

Through reading different articles on adaptation and natural selection with your peers, you will further develop your understanding on natural selection and know what factors play a roll in this process.

Availability of Food

Predator-prey relationship

Climate

Ms. Fisher 02/22/12

Evidence For Evolution:IV. The Fossil RecordHorse EvolutionThe fossil record of the modern horse is a great example of the continuous progression that shows gradual change over millions of years.Notice how the toes gradually get smaller and smaller, leaving only the middle toe, which becomes the foot and hoof of the modern horse.Tetrapod EvolutionEvidence For Evolution:IV. The Fossil RecordThe evolution of four-limbed organisms, or tetrapods, shows a similar progression.

There are no giant leaps; only tiny, gradual incremental changes over millions of years.

New transitional fossils, sometimes called missing links, are continually being discovered.

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Whale AncestorsFossil evidence has demonstrated how whales have evolved from land mammals who walked on four legs.Evidence For Evolution:IV. The Fossil RecordAmbulocetus(50 million years ago)Rodhocetus(47 million years ago)

Whale EvolutionEvidence For Evolution:IV. The Fossil Record

Ancient land-dwelling ancestorsModern baleen whalesOnce again, there is gradual progression in the fossil record, and new fossils are being discovered all the time.

The gradual change can even be seen in the evolution of the blowhole.

16More Transitional FossilsEvidence For Evolution:IV. The Fossil Record

Eupodophis (92 mill.)Archaeopteryx(150 million years ago)Transition between dinosaurs and birdsTransition between lizards and the earliest snakes17More Transitional FossilsEvidence For Evolution:IV. The Fossil Record

Australopithecus afarensis (3.2 mill.)

Dimetrodon (265 mill.)Transition between reptiles and early mammalsTransition between primitive ape-like hominids and more modern humans18Hominid Family TreeEvidence For Evolution:IV. The Fossil Record

Thousands of hominid specimens have been discovered in the past century, allowingscientists to piece together the hominid family tree, extending back about 6 million years to our ape-like ancestors.Every newly discovered species is a transition between its ancestors and descendants on the tree of life. 19

Living FossilsEvidence For Evolution:IV. The Fossil RecordDuck-billed platypusSome modern species, such as the platypus still retain certain primitive traits, that link them to these early transitional missing links.The platypus belongs to a group of primitive mammals called monotremes. This group branched off from reptiles very early, and so these species still lay eggs like their reptile ancestors. 20Living FossilsEvidence For Evolution:IV. The Fossil RecordSimilarly, mudskippers are amphibious fish which are able to gulp air and walk on land using their strong pectoral fins.Not really a living fossil because the species evolved relatively recentlyStill represents a modern look at the transition between sea and land, when the earliest amphibians evolved

Mudskipper

21Animal EmbryologyCan you guess what type of animal this is?Evidence For Evolution:V. Embryology

Animal EmbryologyCan you guess what type of animal this is?Evidence For Evolution:V. EmbryologyTurtle embryoSee the developing shell?

Animal EmbryologyNewly forming vertebrate embryos all look very similar so its difficult to tell what animal youre looking at in the early stages of development. All vertebrates embryos start out with a tail and tiny neck slits resembling gills. This includes humans! In land-dwelling groups such as mammals and reptiles, these slits disappear as the embryo develops, eventually becoming parts of the throat and mouth.In humans, the tail is absorbed into the growing body and remains as the tailbone.Evidence For Evolution:V. EmbryologyAll vertebrates start out almost the same because they all share a common ancestor which was much more primitive.Turtle embryo

early development(all very similar)fetal stage(identifiable as separate species)middle stage embryo(starting to differentiate)Evidence For Evolution:V. EmbryologyVertebrate Embryology

Click here to play Which Embryo is Human? Evidence For Evolution:V. EmbryologyVertebrate EmbryologyNotice how more closely related species tend to resemble each other further along in development.

Side by SideBoth embryos at about 5 weeks gestation!Evidence For Evolution:V. EmbryologyBottle-nosed dolphinHuman

Side by SideEvidence For Evolution:V. EmbryologyBottle-nosed dolphinNotice the beginnings of hind leg buds which form early on and disappear later on in development.This evidence indicates that both chimps and humans received their identical genetic material from a common ancestor who lived about 6 million years ago.humanchimpgorillaorangutangibbonPrimate DNAEvidence For Evolution:VI. DNA and GeneticsComparing our DNA allows us to determine which species are our closest relatives. Humans and chimpanzees DNA are roughly 96% identical. Primate ClassificationEvidence For Evolution:VI. DNA and GeneticshumanchimpbonobogorillaorangutangibbonapesGreat ApeshominidsThese primate groups are determined by how much homologous DNA they have in common.

Primatologist, Jane Goodall and one of her chimp friendsDNA EvidenceDNA evidence is some of the strongest evidence for evolution and the common ancestry of all living things on Earth.It allows us to confirm at the molecular level the extent to which species are related AND estimate how long ago two species probably diverged from their common ancestor.Molecular DNA evidence shows that humans and chimpanzees diverged from one another between 5 and 7 million years ago. That common ancestor diverged from the gorilla family line even earlier, and so on down the family tree.Evidence For Evolution:VI. DNA and GeneticsChromosomal EvidenceAll of the Great Apes have their DNA organized into 24 chromosome pairs, whereas humans have only have 23 pairs.If humans share a common ancestor with all the other Great Apes, we should all have the same number of chromosome pairs because no one could survive if a whole section of DNA just disappeared!

(24 pairs)(23 pairs)How is this possible?Evidence For Evolution:VI. DNA and GeneticsChromosomal EvidenceIf one chromosome pair wasnt just lost, then what could have happened to it?

(24 pairs)(23 pairs)What if two of the earlier ape chromosomes somehow got stuck, or fused, together during cell division at some point in the distant past?Is there any way to verify this?Evidence For Evolution:VI. DNA and GeneticsChromosomal EvidenceActually, it has been verified.

(24 pairs)(23 pairs)By examining the genes found on the ape chromosomes, scientists have found two ape chromosomes that contain the same genes that appear on ONE of our human chromosomes.So its been conclusively demonstrated that they did get stuck together, and all modern humans have inherited that fused chromosome.

Evidence For Evolution:VI. DNA and GeneticsChromosomal EvidenceThis image shows the genes that match up between human and chimp DNA. Note the two chimp chromosomes that match up to our own chromosome #2.

This chart also shows how different sections of DNA have inverted themselves at multiples times in the past. This is one type of mutation.Evidence For Evolution:VI. DNA and Genetics4) Evolution in ActionUsually, the process of evolution takes place so slowly that we cant see it happening.

In selective breeding of livestock and hybridization of crops, humans have sped up and exaggerated this basic process so that we can actually observe the allele frequencies changing over shorter times.Evolution in ActionThere are numerous examples, however, in which a species evolves rapidly enough on their own that we can see evolution in action.A species reproduces very quickly so that numerous generations pass in a short time.Selection pressure is very great.This usually happens because of one or both of the following:

Antibiotic ResistanceBacteria reproduce extremely quickly, and many can double their population in under an hour.

Bacteria can quickly evolve to be resistant to antibiotics if the drugs are not administered properly or for the entire duration of the infection.If any bacteria are not fully wiped out by the antibiotics, the more resistant ones that remain will continue to reproduce.

Sickle-Cell Anemia

Human evolution in actionSickle-cell anemia is a genetic disorder in which the blood cells take on a shriveled sickle shape. The disease can be life-threatening and generally tends to reduce life expectancy significantly.The disease is treatable. In America, it affects about 90,000 people, while there are over 2 million genetic carriers who have one recessive sickle-cell allele, but do not have the actual disease.A Sickle-Cell SafariIt has long been known that the frequency of the disease widely varies between certain ethnicities, and occurs at a much higher ratio among those of African descent. It appears that the frequency tends to correspond to people originating in more tropical climates. What might explain this curious connection?

Incidence of the sickle-cell trait in Africa

Incidence of the sickle-cell trait in AfricaDistribution of MalariaIn 1954, a scientist named Tony Allison found the clue when he realized how closely the frequency of sickle-cell anemia matched the distribution of malaria in Africa.A Sickle-Cell SafariTo explain the extremely high frequencies of the sickle-cell allele, Dr. Allison figured that the genotypes leading to the disease must be giving some sort of survival advantage to those who have the allele (including carriers of the disease).Since the sickle-cell allele seemed to be geographically linked to the distribution of malaria, he hypothesized that the sickle-cell gene must somehow increase the carriers resistance to malaria. With Watson and Cricks recent discovery of the structure of DNA, new molecular evidence soon confirmed Dr. Allisons hypothesis.

A Sickle-Cell SafariEvolution in ActionSince malaria is a much bigger threat to survival than sickle-cell anemia, the sickle-cell trait had become prevalent in the areas where its benefits outweighed the negative effects.Dr. Allison was able to show that the same mutation that led to the sickle-cell trait had occurred at several points in the past in different locations. But it only became prevalent in areas where malaria was widespread.This was an excellent confirmation of the process of evolution occurring in real-time in ways that directly affect humans.