A change in an inherited characteristic of a population over time. Individuals DO NOT evolve!

Evolution Unit 1

Evolution Unit evolution the process of biological change by which descendants come to differ from their ancestors. 3

fossils traces of organisms that existed in the past Fossils gave evidence that species could become extinct. catastrophism theory that states natural disasters such as floods and volcanic eruptions have happened often during Earth s long history Evidence that the appearance of new fossils resulted from species moving into the area from elsewhere after the catastrophic event. Volcanoes, floods, and earthquakes are examples of catastrophic events that were once believed responsible for mass extinctions and the formation of all landforms. 4

gradualism theory that states changes in landforms resulted from slow changes over a long period of time, not a result of a catastrophic event Evidence that canyons were a result of rivers cutting through rock Canyons carved by rivers show gradual change. 5

uniformitarianism theory that states geologic process that shape Earth are uniform through time (gradualism is constant and ongoing) Each layer of rock was formed by the uniform laying down of sediment that still occurs today. 6

SCIENTIST Linnaeus Buffon Erasmus Darwin (Charles grandfather) Lamarck CONTRIBUTION TO EVOLUTION 1700s - Developed a classification system for all types of organisms known at the time System still used today Studied differences in species group of organisms so similar to one another that they can reproduce and have fertile offspring 1700s - Proposed species shared ancestors instead of arising separately Suggested Earth was much older than 6000 years 1700s proposed all living things descended from a common ancestor and that morecomplex forms of life arose from less complex forms 1800s proposed that all organisms evolved toward perfection and complexity 7

Evolution is a process of adaptation Environment plays an active role in the evolution of organisms Changes occur due to needs in the environment Not using a part = part goes away Need a trait to survive = it appears in next generation Using fossil record as evidence

this body builder s offspring would be born buff. Does this occur?

The Clean Room Season: 1 Episode: 7 http://www.cosmosontv.com/watch/230227523738 11

Evolution Unit 12

Charles Darwin Joined the Crew of HMS Beagle in 1831 Naturalist: the idea or belief that nothing exists beyond the natural world. 5 Year Voyage around world Influenced by the ideas of Malthus, he proposed a theory of evolution occurring by the process of natural selection. 13

Islands formed by hot magma reaching surface of crust Older islands (4 million years old) are eroded and lower. Newer islands (7000 years) are steeper

Darwin took a 5 year voyage 1831-1836

Darwin was struck by the variation (the difference in the physical traits) among individuals of the same or similar species. Darwin realized that species may somehow be able to adapt to their surroundings. An adaptation is a feature that allows an organism to better survive in its environment. 16

Most important stop in voyage Small group of volcanic islands 1000 km West of South America Climates were the same, but... The animals on islands were unique: Tortoises Iguanas Finches 18

Island species varied from mainland species & from islandto-island species Each island had long, medium or short neck tortoises: Necks were adapted to food sources. 19

Tortoises with longer necks could reach the higher vegetation in drier areas, so they survived and reproduced, passing their long-necked genes to their offspring. Tortoises in wetter areas had plenty to eat and didn t need long necks to survive and reproduce.

Is an iguana found only on the Galápagos Islands that has the ability, unique among modern lizards, to live and forage in the sea, making it a marine reptile. The iguana can dive over 9 m (30 ft) into the water.

Finches on the islands resembled a mainland finch More types of finches (and tortoises) appeared on the islands than the mainland where the available food was different: Seeds Nuts Berries Insects Finches had different types of beaks adapted to their type of food gathering 22

Each island has slightly different weather: lower islands are barren and dry, higher islands are wetter So, different islands have different vegetation, different habitat. 24

Perhaps a few finches from the S. Am. mainland migrated to the new islands.

Over time their descendents were modified as different groups specialized in eating different foods. http://pustakalaya.olenepal.org/wiki/images/94/9454.jpg http://www.bio.miami.edu/~cmallery/150/evol/24x9.jpg

Darwin observed fossil evidence of species changing over time. The fact that some fossils looked like living species suggested that modern animals might have some relationship to fossil forms. These species NO longer existed. Darwin wondered what had happened to them. Glyptodon, a giant armadillo. Giant ground sloth of South America

Some fossils looked like modern animals. Giant Ground Sloth from Patagonia

Darwin found marine fossils high in the mountains How did they get there? Convergent plate boundaries push up mountains

Darwin also found fossil shells of marine organisms high up in the Andes mountains. Darwin later experienced an earthquake during his voyage and saw firsthand the result: land that had been underwater was moved above sea level. This helped explain why marine animals were found high up in the mountains. Trilobite (marine animal) 30

Evolution Unit 31

Darwin observed that domesticated species of plants and animals seemed to show variation in traits that were not shown in the wild relatives. Natural Variation There are natural differences and lots of variation among individuals of a species. Artificial Selection Humans selectively breed to enhance desired traits among stock or crops. 32

This idea abandoned the theory that species were perfect & unchanging. Farmers have used variation to improve crops & livestock for years. The process by which humans change a species by breeding it for certain traits is called artificial selection. In order for artificial or natural - selection to occur, the trait must be heritable. Heritability is the ability of a trait to be passed down from one generation to the next. 33

When breeding livestock, humans choose the parents with traits they want in the offspring. Ex: dogs, cows, horses, pigeons 35

Evolution Unit 36

Darwin used what he knew about artificial selection (human s selecting useful traits for their own benefit) for his theory of natural selection: Mechanism by which individuals that have inherited beneficial adaptations produce more offspring on average than do other individuals. In nature, the environment is the selective agent. Therefore, in nature, characteristics are selected only if they give advantages to individuals in the environment as it is right now. 37

Malthus Influence: Observed babies were being born faster than people were dying. Office of Population Research, Princeton University High birth rates & limited resources would force life & death competition War Famine Disease worked against growing populations Population size was limited by resources such as the food supply Each Species Struggles For: Food Living Space Mates

Malthus reasoned that if the human population continued to grow unchecked, sooner or later there would be insufficient living space & food for everyone. Plants & animals produce far more offspring than can be supported. Most will die If they didn t, the Earth would be overrun! Death rate will increase to balance the population size and the limited food supply in the environment. 39

Upon his return to England, Darwin developed his observations into the Theory of Evolution, but he did not publish for 25 years... Darwin knew that his theory was extremely controversial and would be attacked. His theory challenged both the established religious & scientific beliefs, particularly about the creation of man. 40

Alfred Russell Wallace independently came to same conclusion as Darwin that species changed over time because of their struggle for existence. When Darwin read Wallace s essay, he knew he had to publish his findings. Darwin made four main points in his book: 1. overproduction 2. variation 3. selection 4. adaptation 41

overproduction while having many offspring raises the chance that some will survive, it also results in competition for resources 42

variation the differences that exist in every population (defined as all the individuals of a species that live in an area) are the basis for natural selection. Differences result from characteristics inherited from parents or result from mutations. 43

In a given environment, having a particular trait can make individuals more or less likely to survive and have successful offspring. So, some individuals leave more offspring than others do. 44

Adaptation sometimes a certain variation or trait allows an individual to survive better than other individuals it competes against in its environment. More successful individuals are said to be more fit. 45

An Inherited trait present in a population because it helps individuals survive AND reproduce in a given environment. Adaptations are what individual organisms have, like longer beaks, darker fur, lighter skin, better oxygen carrying capacity, etc. Evolution is the change in a population over time. Individuals may have adaptations, but they DO NOT CREATE adaptations through use. (That s Loser Lamarck!)

Fitness ability of an individual to survive & reproduce Individuals with low fitness die & produce few offspring Adaptation inherited characteristic that increases fitness (an organisms chance for survival) Adaptations can be: Physical speed, camouflage, claws, etc. Behavioral solitary, herds, packs, activity, etc. 47

Survival of the Fittest is also known as Natural Selection It s the driving force for evolution. During the struggle for resources, the strongest will survive & reproduce.. 48

Natural Selection The unequal ability of individuals to survive and reproduce leads to a gradual change in a population with favorable characteristics accumulating (building up) over generations. New species evolve 49

Darwin proposed that organisms descended from common ancestors. This implies all living organisms are related, that all organisms come from a single tree of life. Idea states that organisms change with time. These changes cause the evolution of new species. 50

Species today look different from their ancestors. Organisms have descended with changes from other species over time. 51

Natural selection acts on phenotypes, or physical traits, rather than on genetic material itself. New alleles are not made by natural selection, they occur by genetic mutations. Natural selection can act only on traits that already exist. 52

Ex: Finches on the Galapagos Islands Drought in 1977 reduced the amount of small soft seeds finches preferred. Because large-beaked finches were able to crack the large, tough seeds, they did not starve. The next year, there was a big increase of large-beaked hatchlings and most of the small beaked finches died. 53

Each type of finch occupies a different niche (ecological role) so competition is reduced. 54