Warm Up With your partner, write a sentence (20 words or less) using two of the following terms to show your knowledge of genetic engineering: * Transgenic Organisms, Recombinant DNA, Recombinant Bacteria, Selective Breeding, PCR, Gel Electrophoresis, Genetically Modified
Changes Over Time SOL: BIO 8 a-e
Standard BIO 8 a-eThe student will investigate and understand how populations change through time. Key concepts include: • a) evidence found in fossil records; • b) how genetic variation, reproductive strategies, and environmental pressures impact the survival of populations; • c) how natural selection leads to adaptations; • d) emergence of new species; and • e) scientific explanations for biological evolution.
Theory of Evolution • Science is made up of many ideas, theories, and laws. Many of these ideas have gone through many changes throughout the years. • Our job as life-long learners is to examine all the evidence concerning a particular topic. • Evolution is part of the Core Knowledge curriculum for Biology. • The origin of life is a sensitive subject for many people. There are many theories concerning the change in things over time. • You may hold a different view than what will be presented as part of the Core Knowledge curriculum. • Out goal is to explore the theory of evolution from a scientific standpoint, not to discount any other theories on the origin of life.
Charles Darwin The Father of Evolution
History • Darwin’s World (1809 - 1875) • Height of the British colonial period. • Beginning of the Industrial Revolution. • New Ideas: • Taxonomy of Carolus Linnaeus • Lyell’s “Principles of Geology”
Binomial System of Nomenclature Carolus Linnaeus (1707 – 1778) Believed in the “Fixity of Species”
Charles Lyell • Father of Geology
Charles Lyell’s view of the process of formation of sedimentary rock
Suggests that sedimentary rock is very old – therefore the species that are represented in this rock must also be old. • Most fossils are found in sedimentary rock. • Older fossils will be found below younger fossils.
Knowledge Check Who was Linnaeus? Who was Lyell? If Lyell looked at fossils is a cross section of sediment, would the fossils more towards the surface be older or younger than those below? Why?
Charles Darwin At the age of 22, he joined a 5 year expedition aboard the HMS Beagle to map the coast of South America
Charles Darwin’s Theory of Evolution: 1. Members of a population have heritable variations.(Inheritance of traits)
2. In a population, more individuals are produced than the environment can support. They compete for food and shelter. (overpopulation- struggle for survival).
3. Some individuals have adaptive characteristics that enable them to survive and reproduce better than other individuals (survival of the fittest).
4. An increasing number of individuals in succeeding generations have these adaptive characteristics (natural selection)
Knowledge Check Summarize the four components of Darwin’s theory of evolution.
Darwin described his theory in the form of a long essay which he called “On the Origin of Species”.
Concerned about the public’s response to his ideas(remember what happened to Galileo) Arranged to publish his work … AFTER HIS DEATH !!
Charles Darwin At age 50 (1859) At age 65 (1874)
Charles Darwin Before publication After publication
Through his observations made in the Galapagos Islands, Charles Darwin formulated a theory of how species change over time, called natural selection.
Natural selection is governed by the principles of genetics. • The change in the frequency of a gene in a given population leads to a change in a population and may result in the emergence of a new species. • Natural selection operates on populations over many generations.
Knowledge Check What was the name of Darwin’s book? On what island did Darwin make observations that lead him to develop his ideas about natural selection? Explain how natural selection can be observed in a population. (Think Hardy Weinberg)
Evolution • A change in successive generations of organisms, due to random mutation and changes in the organisms’ surroundings
Evolution takes place through a set of processes that include: • mutation, • adaptation, • natural selection, • extinction.
Mutation • Genetic mutations and variety produced by sexual reproduction allow for diversity within a given population. • Many factors can cause a change in a gene over time.
Mutation • Mutations are important in how populations change over time because they result in genetic changes to the gene pool.
Mutations are inheritable changes because a mutation is a change in the DNA code
Mutation- a change in the DNA A mutation may result in a: 1.favorable change or adaptation in genetic information that improves a species’ ability to exist in its environment
Mutation- a change in the DNA 2. an unfavorable change that does not improve a species’ ability to exist in its environment.
Mutation- a change in the DNA 3. in a change in the genetic information that neither harms nor helps the species.
Adaptation • Adaptations are structures, functions, or behaviors that enable a species to survive.
Adaptation • Depending on the rate of adaptation, the rate of reproduction, and the environmental factors present, structural adaptations may take millions of years to develop.
Natural Selection • the survival and reproduction of the individuals in a population that exhibit the traits that best enable them to survive in their environment. • The Survival of the Fittest
Natural Selection • Populations produce more offspring than the environment can support.
Natural Selection • The unequal ability of individuals to survive and reproduce leads to the gradual change in a population, generation after generation over many generations.
Natural Selection • Organisms with certain genetic variations will be favored to survive and pass their variations on to the next generation.
These five canine species evolved from a common ancestor through natural selection Jackal African wilddog Wolf Coyote Fox Thousands tomillions of yearsof natural selection Ancestral canine
When humans choose organisms with specific characteristics as breeding stock, they are performing the role of the environment • This is called “artificial selection” Example of artificial selection in plants: five vegetables derived from wild mustard
Artificial Selection in Animals: Dog Breeding German shepherd Yorkshire terrier English springerspaniel Mini-dachshund Golden retriever Hundreds tothousands of yearsof breeding(artificial selection) Ancestral dog
The evolution of insecticide resistance is an example of natural selection in action Chromosome with geneconferring resistanceto insecticide Additionalapplications of thesame insecticide willbe less effective, andthe frequency ofresistant insects inthe populationwill grow Insecticideapplication Survivor
Knowledge Check What is evolution? Identify the four processes of evolution. Explain how each process can lead to evolutionary change.
Extinction • no longer in existence; "the extinction of a species"
If a species does not include traits that enable it to survive in its environment or to survive changes in the environment, then the species may become extinct.
Individuals of a population exhibit a range of variations in a trait as a result of the variations in their genetic codes.