Transcript Evolution
Evolution The Origin of Species Charles Darwin 1. Natural Selection/Survival of the Fittest • Adaptations-Allow organisms to survive and reproduce in their environment • Variations-Differences 2. Principle of common descent • All organisms come from a common ancestor 3. Book is On the Origin of Species Evolution & Life’s Diversity The physical traits and behavior that enable organisms to survive and reproduce in their environment is fitness Fitness arises from adaptation Common Descent-Each species has descended from other species over time The Age of the Earth The Age of The Earth The Earth is over 4 billion years old; determined by radioactive/radiometric dating(4.6 billion). Relative Dating is a technique used by scientists relative to fossils and other ones in different layers of rock. Half-Life-Length of time it takes ½ of a radioactive element to decay The Age of The Earth Elements with different half lives provide natural “Clocks” that “tick” at different rates When interpreted correctly, they help scientists date rocks and specimen of different ages Uranium 238, Potassium 40, & Argon 40 are a few radioactive elements The Age of The Earth Carbon 14(C14)is used to determine or date material that was once alive, such as bones or objects that contained onceliving materials Is not useful in dating substances more than 60,000 years old The Fossil Record The Fossil Record • Most fossil are found in sedimentary rock. • S. rock results when rain, heat and cold breaks down existing rocks into small particles of sand, silt, and clay. • Paleontologists are scientists who study fossils • Evidence of past life forms The Fossil Record • Fossil records also tell us of major changes in the earth’s climate • Fossil shark teeth were found in Arizona • Giant fossil ferns were found in Canada. Fossil Discoveries • Fossils – remains of dead organisms (in rock, petrified bones and wood, shells, impressions of body forms) Evidence From Living Organisms Evidence From Living Organisms Show active genes (particular sequences of genes) derived from a common ancestor during early stages of development Homologous structures- Structures that develop from the same body part; similar in appearance but have different functions Homologous Structures Vestigial Organs Serve little or no purpose Similarities in chemical compound DNA, RNA, and ATP; Ex: human appendix, tail bone Provides powerful evidence that all living things evolved from common ancestors Developing a Theory of Evolution Developing a Theory of Evolution Jean Baptiste de Lamarck- Thought organisms had an inborn urge to better themselves and become more fit to their environment Desire to Change Use and Disuse Inheritance of Acquired Traits Developing a Theory of Evolution Thomas Malthus- Believed people were being born at a much faster rate than they were dying Charles Lyell- a geologist who said the earth was very old and had changed over time. Artificial selection-When animals are bred for desired traits Evolution by Natural Selection Evolution by Natural Selection • Survival of the fittest-Individuals whose characteristics are well-suited to their environment to survive where as others don’t • A British ecologist,H.B.D. Kettlewell, demonstrated natural selection with dark and light peppered moth Natural Selection and the Peppered Moth Genetics & Evolutionary Theory Genetics & Evolutionary Theory Genes- Units of variations; may occur from Population-A collection of individuals of the mutations same species in a given area whose members can breed with one another Gene Pool-When organism share a common group of genes Relative Frequency-The number of times an allele occurs in a gene pool compared to the # of times other alleles for the same gene occur The Development of New Species The Development of New Species Species – basic unit of taxonomic classification Population of closely related and similar organisms In sexually reproducing organisms, the similar organisms must be able to breed and produce viable, fertile offspring Speciation-How many species evolve from old ones Niche-The combination of an organisms “profession” and the place in which it lives. Reproductive Isolation-The agent for the formation of new species The Development of New Species Darwin’s Finches Step 1: Founding Fathers & Mothers; descendants of a few ancestral finches Step 2: Separation of population. Step 3: Changes in the Gene Pool Step 4: Reproductive Isolation; prefer not to mate because of mating behavior Step 5: Sharing the Same Island; coexistence, extinction, or further evolution Speciation & Adaptive Radiation Adaptive Radiation-Process by which species gives rise to many species; also known as divergent evolution. A number of species diverge or move away from a common ancestral form. Convergent Evolution- Phenomenon in which adaptive radiations among different organisms produce species that are similar in appearance and behavior Convergent Evolution Unrelated species Similar environments Similar adaptations (more alike) Converge or come together Divergent Evolution/Adaptive Radiation Related species Different environment Different adaptations Develop new species Diverge-move apart Evolutionary Theory Evolves The Development of New Species • Genetic Drift-A random change in the frequency of a gene (an allele can become common in a population by chance) Demonstration of Genetic Drift New Species Development • Unchanging Gene Pools- A species remains the same for a long time • Gradual and Rapid Evolutionary Change Gradualism- theory that evolutionary change occurs slowly and gradually Gradualism vs Punctuated Equilibrium Rapid Evolution Can Occur 1. 2. 3. • • Isolation New Environment Dramatic Changes in the earth Mass Extinction-Phenomenon in which many species vanish; some are caused by changes in global climates; others are uncertain Punctuated Equilibria- Long stable periods interrupted by brief periods of change