Binders by Tuesday Be on Time Be ready to Learn Any problems with summer assignment Due on Tuesday

Charles Darwin and Natural Selection

Charles Darwin

Question for Thought Earth has millions of other kinds of organisms of every Earth has millions of other kinds of organisms of every imaginable shape, size, and habitat. imaginable shape, size, and habitat. This variety of living things is called biological diversity. How did all these different organisms arise? How are they related? How are they related?

In your own words, describe what YOU think the theory of evolution means… ?? ???

Darwin’s Theory of Evolution Evolution, or change over time, is the process by which modern organisms have descended from ancient organisms. A scientific theory is a well-supported testable explanation of phenomena that have occurred in the natural world.theory

How did Darwin come up with his Theory

Voyage of

Patterns of Diversity

Living Organisms and Fossils D arwin collected the preserved remains of ancient organisms, called fossils. S ome of those fossils resembled organisms that were still alive today. O thers looked completely unlike any creature he had ever seen. A nd some seemed to have disappeared

As Darwin studied fossils, new questions arose. Why had so many of these species disappeared? How were they related to living species?

The Galapagos Island

The Galapagos today is an amazing place. Animals live there that are found nowhere else on earth. This makes them endemic Perhaps the most famous of the endemic birds are the finches, of which there are 13 different species The islands are a natural laboratory, and one in which evolution can be observed.

Endemics Among the kinds of animals found here and nowhere else: 1 penguin species 1 giant tortoise species 1 marine iguana species 7 species of lava lizard 14 species of sea cucumber 1 species of sea lion 1 species of hawk several species each of mockingbirds, doves, owls, flycatchers, and yellow warblers 16

The Galapagos Island The smallest, lowest islands were hot, dry, and nearly barren-Hood Island- sparse vegetation The higher islands had greater rainfall and a different assortment of plants and animals-Isabela- Island had rich vegetation.

Animals

Q1 Endemic means: A: The end is imminent. B: The species isn’t found anywhere else. C: The species has very specific habitat requirements. D: The species needs to be protected. E: The species is extinct.

Darwin was fascinated in particular by the land tortoises and marine iguanas in the Galápagos. Giant tortoises varied in predictable ways from one island to another. The shape of a tortoise's shell could be used to identify which island a particular tortoise inhabited.

The Finches The 13 finch species include: 6 species of ground finches 3 species of tree finches 1 woodpecker finch 1 vegetarian finch 1 mangrove finch 1 Coco Island finch A warbler finch that looks more like a warbler than a finch (one of the tree finches). The woodpecker finch actually uses cactus spines to dig grubs out of branches! 27

Peter and Rosemary Grant Scientists Peter and Rosemary Grant have studied many of these species for the past thirty years. Spend months at a time on the islands Often know every finch on an island CCog 28

Let’s take a closer look at their data

Graph showing the distribution of beak depths for medium ground finches in Year 1 30

Q1: What is the average depth of the finches’ beaks in Year 1? A: about 7mm B: about 8mm C: about 9.5mm D: about 10mm E: about 11mm 31

How much was the biggest difference in beak depth? A: 2 mm B: 4 mm C: 6 mm D: 8 mm E: 10 mm 32

A Change in the Weather Year 2 – what happened? Like most years, some rain fell the first week of January. The rest of January, there was one small shower. The total rainfall for the entire year: 24mm. In a normal year, 130mm of rain would fall. In Year 1, 137mm of rain fell. 33

The ground finches feed on seeds Year 1 June: 1m 2 of lava on the island has over 10 grams of seeds. Year 2 June: 6 grams of seeds per m 2. Year 2 December: 3 grams of seeds per m 2. In the drought, the plants conserved their resources and did not produce new seeds. Similarly, the finches did not mate and did not produce eggs in Year 2 34

Seeds A variety of seeds are produced on the island. Finches prefer the softest seeds, which are the easiest to open. The seeds above are seeds of a plant called Caltrop, in the genus Tribulus. These are among the hardest to eat. It takes a medium ground finch with a beak at least 11mm long to open one. Ground finches with beaks that are 10.5mm long or less haven’t even been seen trying to eat them. 35

Prediction? What do you think will happen to the size of the finch population between Years 1 and 3? (Remember, Year 2 is a drought year.) Sketch a rough graph of your prediction 36

Q2: What do you think a graph of population size would look like for Year 1 to Year 3? A: Time B: C: D: 37

Another Year of Change On one day in January of Year 3, more than 50mm of rain fell on the island. The plants finally flowered and produced new seeds. The Grants and their colleagues returned to the Galapagos. They found the finch population had been decimated. No new finches hatched in Year 2. Only one finch born in Year 1 survived to Year 3. 38

Year 3 Data 39

Q3: What was the average beak depth in 1978? (Remember that the average beak depth in 1976 was 9.5 mm.) A: Just under 7mm B: About 8mm C: About 9mm D: Just under 10mm E: Just under 11mm 40

Evolution is: A change in the frequency of an allele, such as an allele for beak depth, is the basic definition of evolution. 41

Q4: Did the finch population evolve from 1976 to 1978? A: Yes B: No C: Maybe D: I don’t know 42

Evolution by natural selection The Grants first went to the Galapagos to take a quick snapshot of finch diversity. Within only a few years, they saw natural selection. In the course of one season, the beaks got 0.54mm deeper and 0.39mm longer. 43

Evolution by natural selection The beak size and shape was changing, right before the Grants’ eyes! This is definitely evolution as we defined it earlier. 44

Surprises? Two things surprised the Grants: 1. Evolution could occur quickly enough to observe within a few field seasons. Darwin believed that we did not have a long enough lifespan to observe evolution. A single weather event can cause evolution, if there are traits that affect survival and if there is variation in those traits. 45

Surprises? 2. Evolution can occur at very small scales. The Grants’ measurements were very careful. The birds weren’t used to humans, and so were easy to catch and measure They couldn’t see a difference in even 1mm between two finches, but their measurements could And due to those measurements, they could find that 0.5mm was enough to make a difference between survival and death in a drought year 46

Q: If beak depth increased during the drought, primarily due to selective mortality, can we really say that this natural selection was driven by environment favoring the survival of birds with deeper beaks? A: No. Beak depth changed due to birds dying, not to birds surviving. B: Yes. Birds with deeper beaks survived at a higher rate than birds with shallower beaks. C: I’m really confused. 47

The Journey Home Darwin Observed that characteristics of many plants and animals vary greatly among the islands Hypothesis: Separate species may have arose from an original ancestor

Ideas that shaped Darwin’s Thinking James Hutton: 1795 Theory of Geological change Forces change earth’s surface shape Changes are slow Earth much older than thousands of years

Ideas that Shaped Darwin’s Thinking Charles Lyell Book: Principles of Geography Geographical features can be built up or torn down Darwin thought if earth changed over time, what about life?

Lamarck

Lamarck’s Theory of Evolution Tendency toward Perfection (Giraffe necks) Use and Disuse (bird’s using forearms) Inheritance of Acquired Traits Are you still paying Attention?

Population Growth Thomas Malthus-19th century English economist If population grew (more Babies born than die) Insufficient living space Food runs out Darwin applied this theory to animals

Publication of Orgin of Species Russel Wallace wrote an essay summarizing evolutionary change from his field work in Malaysia Gave Darwin the drive to publish his findings

Natural Selection & Artificial Selection Natural variation--differences among individuals of a species Artificial selection- nature provides the variation among different organisms, and humans select those variations they find useful.

slide 4

Adaptation/Mutation/Natural Selection/ Selective Breeding Examples Primate A Primate B Mutation Adaptation Natural Selection

Adaptation/Mutation/Natural Selection/ Selective Breeding Examples Primate A Primate B MutationDevelops opposable thumb Adaptation Natural Selection

Adaptation/Mutation/Natural Selection/ Selective Breeding Examples Primate A Primate B MutationDevelops opposable thumbDoes NOT develop opposable thumb Adaptation Natural Selection

Adaptation/Mutation/Natural Selection/ Selective Breeding Examples Primate A Primate B MutationDevelops opposable thumbDoes NOT develop opposable thumb AdaptationBecause of his thumbs, primate A can now handle tools and has a better chance of survival Natural Selection

Adaptation/Mutation/Natural Selection/ Selective Breeding Examples Primate A Primate B MutationDevelops opposable thumbDoes NOT develop opposable thumb AdaptationBecause of his thumbs, primate A can now handle tools and has a better chance of survival Primate B is less adapted to his environment so it is more difficult for him to survive Natural Selection

Adaptation/Mutation/Natural Selection/ Selective Breeding Examples Primate A Primate B MutationDevelops opposable thumbDoes NOT develop opposable thumb AdaptationBecause of his thumbs, primate A can now handle tools and has a better chance of survival Primate B is less adapted to his environment so it is more difficult for him to survive Primate A passes mutation on to his children Natural Selection

Adaptation/Mutation/Natural Selection/ Selective Breeding Examples Primate A Primate B MutationDevelops opposable thumbDoes NOT develop opposable thumb AdaptationBecause of his thumbs, primate A can now handle tools and has a better chance of survival Primate B is less adapted to his environment so it is more difficult for him to survive Primate A passes mutation on to his children Primate B produces more children without the opposable thumb Natural Selection

Adaptation/Mutation/Natural Selection/ Selective Breeding Examples Primate A Primate B MutationDevelops opposable thumbDoes NOT develop opposable thumb AdaptationBecause of his thumbs, primate A can now handle tools and has a better chance of survival Primate B is less adapted to his environment so it is more difficult for him to survive Primate A passes mutation on to his children Primate B produces more children without the opposable thumb Natural Selection Many Generations later those Out number those without because environment. Today all primates primates with opposable they are better suited for their have opposable thumbs

Evolution by Natural Selection The Struggle for Existence-members of each species have to compete for food, shelter, other life necessities Survival of the Fittest-Some individuals better suited for the environment

Over time, natural selection results in changes in inherited characteristics of a population. These changes increase a species fitness in its environment

Evidence for Evolution The Fossil Record- Layers show change Geographic Distribution of Living Things Homologous Body Structures Similarities in Early Development

structures that have different mature forms in different organisms, but develop from the same embryonic tissue Homologous Structures -

Evidence for Evolution Vestigial organs-organs that serve no useful function in an organism

Vestigial organs in Human Body

Similarities in Early Development

Analogous Structures Structures of different species having similar or corresponding function but not from the same evolutionary origin Structuresspeciesfunctionevolutionaryorigin

Summary of Darwin’s Theory Individuals in nature differ from one another Organisms in nature produce more offspring than can survive, and many of those who do not survive do not reproduce.

Summary of Darwin’s Theory Because more organisms are produce than can survive, each species must struggle for resources Each organism is unique, each has advantages and disadvantages in the struggle for existence

Summary (cont.) Individuals best suited for the environment survive and reproduce most successful Species change over time

Summary (cont.) Species alive today descended with modification from species that lived in the past All organisms on earth are united into a single family tree of life by common descent

Can you make an ideal species for a environment? On a piece of paper number 1-5 Next to each number pick a letter A-E and write down one next to each number You can repeat letters if you wish

Climate A=Hot and dry (example: desert),desert B=Hot and rainy (example: tropical rain forest),tropical rain forest C=Moderate temperatures and high rainfall (example: deciduous forest)deciduous forest, D=Moderate temperatures and low rainfall (example: grasslands)grasslands, E=Below zero temperatures (example: tundra)tundra

Type of Terrain A=Volcanic islands, B=Swampy, C=Mountains, D=Flatlands, E=Underground

Predators A=Large birds of prey, B=Humans, C=Cheetahs, D=Wolves, E=Bears

Food A=Fish, B=Leaves of tall plants or trees, C=Roots of plants, D=Fast running animals, E=Insects

Biggest Threat to Survival A=Pollution, B=Deforestation, C=Disease, D=Not producing enough offspring, E=Lack of food or water

Your Job is to: Decide which adaptations would be suitable for your conditions. Remember those with the most favorable conditions will survive and reproduce Show how these adaptations are apparent on their species. Draw their ideal species fo the environment Explain what those adaptations are and why they are desirable for that situation