41
• Evolution is the generation to generation change in the proportion of different inherited genes in a population that accounts for all the changes that have transformed life over an immense time
• Two ideas about life on Earth before Darwin1. Species are fixed, or permanent2. Earth is less than 10,000 years old and is also
relatively unchanging
Georges Buffon• French naturalist, Georges Buffon suggested that
earth might be much older than a few thousand years
• he observed that specific fossils and some living animals were similar but they weren’t exactly alike
Jean Baptiste Lamarck
• French naturalist, Jean Baptiste Lamarck made an explanation of Buffon’s observations
• he said that life evolves, or changes
• he figured that species are not permanent
• he explained that evolution is a process of adaptation
• adaptation is an inherited characteristic that improves an organism’s ability to survive and reproduce in a particular environment
Inheritance of Acquired Characteristics
• Lamarck said that by using or not using certain body parts, an organism develops certain characteristics
• he thought that these characteristics would be passed on to the offspring
• He called that idea, inheritance of acquired characteristics
Darwin’s Journey around the World
• The Beagle left for a voyage around the world in 1831
• Charles Darwin was a 22-year-old who went on the voyage
• Darwin observed and collected thousands of specimens of South American plants and animals from diverse environments
The Voyage of the Beagle
Darwin’s Journey around the World
• Darwin studied organisms on the Galapagos Islands
• He observed that some of the species on the islands were similar to, but different from the plants and animals of the nearby mainland
• He figured that the mainland species had changed after they colonized the islands and adapted to their new environments
• Darwin read a lot of writings of geologist Charles Lyell
• Charles Lyell said that gradual and observable geologic processes, for example erosion, can explain the physical features of Earth
• Darwin thought that earthquakes moved fossils
Darwin Publishes His Theory
• Darwin read an essay by Thomas Malthus on human populations
• Malthus wrote that population can grow a lot faster than the rate supplies and food can be produced
• Darwin wrote a 200-page essay on his idea in 1844 put he didn’t publish it
• British naturalist, Alfred Wallace, had the same ideas as Darwin
• Darwin combined his work and Wallace’s and wrote the book, The Origin of Species
Darwin’s Two Main Points
• Darwin’s first idea was descent with modification• Descent with modification is a process by which
descendants of ancestral organisms spread into various habitats and accumulate adaptations to diverse ways of life
• His second idea was natural selection• Natural Selection is a process by which individuals
with inherited characteristics well-suited to the environment leave more offspring than do other individuals
• Fossils are preserved remains or marking left by an organism that lived in the past
• Most fossils are found in sedimentary rocks• Rock layers form when the rates of
sedimentation or types of particles that form the sediments, vary over time
Fossils
Rock Layers
Fossil Record• Younger rock layers are usually on top of older
ones• Fossil Record is the chronological collection of
life’s remains in sedimentary rock layers• Provides evidence of Earth’s changing life• The oldest rocks are found in Greenland,
which are about 3.5 billion years old
• Some fossils show organisms that have become extinct
• Extinct is that something is no longer existing as a living species on Earth
• Darwin’s observations tells that organism’s today, evolved from ancestral forms
• Australia is home to many pouched animals but few placental animals because the island was separated from the mainland and evolved differently
• Homologous structures are similar structures found in more than one species that share a common ancestor
• Some have a major function in one species but are less important in a related species
• Vestigial structures are remnant of a structure that may have had an important function in a species’ ancestors, but has no clear function in the modern species
Similarities in Structure
• If two organisms have very similar genes, they are more closely related
• Humans are more closely related to primates than to other vertebrates
• Population is a group of individuals of the same species living in a particular area at the same time
• Darwin collected finches from different islands in the Galapagos
• These finches contributed to the thoery of natural selection
Darwin’s Theory
• Darwin found 13 species of finches that were unique to the Galapagos islands
• They resemble one finch found on the South American mainland
• Each finch had a unique beak which adapted to specific food found on the different islands
• Darwin realized that organisms produce a great number of offspring
• The production of more individuals than the environment can support, lead to struggle for existence
• Only a small number of offspring will survive
Darwin’s First Observation
Darwin’s Second Observation
• Darwin found variation among the organisms of a population
• Variation is the difference among members of a species
• A lot of the variation is passed on from generation to generation
Theory of Natural Selection
• Overproduction of offspring and variation among the individuals of a population led to the theory of Natural Selection
• Natural Selection happens over many generations and it can create two different species from one ancestor
• Artificial Selection is the selective breeding of domesticated plants and animals to produce offspring with desired genetic traits
• Can produce a great deal of change in a species in a short time
• Dogs are an example of artificial selection
Artificial Selection
• Pesticides are poisons used to kill insects that are pests in plants and humans
• Some of the insects are naturally resistant to the pesticide so they have more offspring and all the population becomes resistant
Pesticides
• Evolution occurs because of population not because of the individual
• Gene Pool is all of the alleles in all the individuals that make up a population
• It is where genetic variation, or the raw material of evolution, is stored
Changes in Gene Pools
Random/ Not Random
• The following are random: -mutations -sexual recombination
• The following are not random: -evolution -natural selection
Microevolution vs. Hardy-Weinberg Equilibrium
• Microevolution is evolution on the smallest scale- a generation-to-generation change in the frequencies of alleles within a population
• Unlike microevolution, Hardy-Weinberg equilibrium is condition that occurs when the frequency of alleles in a particular gene pool remain constant over time
Hardy-Weinberg Equilibrium
• Genetic Drift is the change in the gene pool of a population due to chance
• The smaller the population is, the more impact genetic drift has on it
• Genetic drift is likely to happen where a new organism comes to a new habitat
• Gene Flow is the exchange of genes between populations
• Occurs when fertile individuals or their gametes migrate between populations
• Natural selection and genetic drift can influence whether the frequency of a new mutation increases or not in a population
Gene Flow and Mutation
Mutation
• Natural selection is sometimes known as “struggle for existence” and “survival of the fittest”
• Fitness is contribution that an individual makes to the gene pool of the next generation compared to the contributions of other individuals
• If an organism is more fit and is more contributed, it will produce more offspring
• It happens when red blood cells are shaped wrong in individuals
• People are weak, have pain, have damaged organs, and can die
• Caused by recessive allele• Heterozygous individuals do not get the
disease
• Antibiotic is a medicine that kills or slows the growth of bacteria
• Saved lives of millions of people• It is dangerous to use too much because it can
cause new resistant strains to appear
Bibliography• http://glitterkiss.com• http://cooltext.com• http://www.ansp.org/museum/jefferson/images/Buffon_younger.jpeg• http://cnho.files.wordpress.com/2009/08/lamarck296.jpg• http://www.oum.ox.ac.uk/learning/htmls/images/map.gif• http://anxietyindex.com/anxietyindex/wp-content/uploads/2009/02/origin-of-the-species.jp
g• http://img165.imageshack.us/i/homologymy6.jpg/• http://biology.unm.edu/ccouncil/Biology_112/Images/FinchTypes.jpg• http://www.bbc.co.uk/schools/gcsebitesize/science/images/dogs.jpg• http://www1.flamingtext.com• http://faculty.southwest.tn.edu/rburkett/GB%20Pro15.jpg• http://collectionscanada.ca/obj/021018/f4/nlc011152-v6.gif
