THEORY OF EVOLUTION 1 11242020 SB 5 a

THEORY OF EVOLUTION 1 11/24/2020 SB 5 a and d

STANDARD AND ELEMENT SB 5. Students will evaluate the role of natural selection in the development of theory of evolution. a. Trace the history of theory. d. Relate natural selection to changes in organisms. 2 11/24/2020 SB 5 a and d

ESSENTIAL QUESTIONS How did Darwin’s contributions change the view of theory of evolution? What causes genetic variation? Why can’t we get rid of all pests like roaches, flies and mosquitoes? 3 11/24/2020 SB 5 a and d

WHAT IS EVOLUTION? Theory of Evolution explains the process by which modern organisms have descended from ancient organisms. 4 11/24/2020 SB 5 a and d

HISTORY BEHIND THEORY Proposed by Charles Darwin (Darwinism) and Alfred Wallace in 1858 Earlier concepts of evolution Carolus Linnaeus (a Swedish botanist who laid the foundations for the modern scheme of nomenclature). Georges Louis Leclerc de Button- challenged many of the accepted ideas of the day. Proposed that species shared ancestors instead of rising separately. Eramus Darwin- Darwin’s grandfather. Proposed that all living things were descended from a common ancestor and that more complex forms of life arose from less complex forms. 11/24/2020 SB 5 a and d 5

EARLIER CONCEPTS ON EVOLUTION CONT. Jean-Baptiste Lamarck (Lamarckism)-Proposed that by selective use or disuse of organs, organisms acquired or lost certain traits during their lifetime. This is known as the Inheritance of acquired traits Thomas Malthus (economist)- Reasoned that if the human population continued to go unchecked, sooner or later there would be insufficient living food and space for everyone. George Cuvier- Proposed theory of catastrophism that natural disasters such as floods and volcanic eruptions have happened often during Earth’s long history. These events shaped landforms and caused species to become extinct in the process 6 11/24/2020 SB 5 a and d

EARLIER CONCEPTS OF EVOLUTION CONT. James Hutton (geologist)- Proposed that changes he observed in landforms resulted from slow changes over a long period of time, known as gradualism. Argued that the laying down of soil or the creation of canyons by rivers cutting through rock were not the result of large events, rather slow processes that happened in the past. Charles Lyell (geologist)- Expanded Hutton’s theory of gradualism into theory of uniformitarianism. Proposes that the geologic process that shapes Earth are uniform through time. Observed processes that made small changes in Earth. 7 11/24/2020 SB 5 a and d

DARWIN’S OBSERVATIONS Great diversity among species Animals were well adapted to habitat Different species live in similar ecosystems Animals on the Galapagos islands varied according to where they lived Tortoises Finches 8 11/24/2020 SB 5 a and d

DARWIN’S FINCHES 9 11/24/2020 SB 5 a and d

DARWIN’S CONCLUSION Darwin published a book titled “On the Origin of Species” in which he proposed a mechanism for evolution that he called natural selection. He presented evidence that demonstrated that the process of evolution had been taking place for millions of years and continues in all living things 11 11/24/2020 SB 5 a and d

NATURAL SELECTION VS. ARTIFICIAL SELECTION Artificial Selection- The process by which humans change a species by breeding it for certain traits. Humans determine which traits are favorable and breed individuals that show those traits. Natural Selection- The mechanism by which individuals that have inherited beneficial adaptations produce more offspring than do other individuals. The environment is the selective agent, therefore, characteristics are selected only if they give advantages to individuals in the environment as it is right now. 12 11/24/2020 SB 5 a and d

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STRUGGLE FOR SURVIVAL The Struggle for Existence Proposed by Thomas Malthus Members of each species compete regularly to obtain food, living space, and other necessities of life These resources are limiting factors Disease and limited food supply keeps populations small. Populations consist of all the individuals of a species that live in an area. 14 11/24/2020 SB 5 a and d

THE PROCESS OF EVOLUTION BY NATURAL SELECTION Variation Differences among individuals result from differences in the genetic material of the organisms, whether inherited from a parent or resulting from a genetic mutation. Overproduction More organisms than can survive are produced, this increases the chance that some will survive. Adaptation Certain variations allows an individual to survive better than other individuals it competes against in its environment. Descent with modifications Natural selection will result in species with adaptations that are well suited for survival and reproduction. Offspring will have these traits it environmental conditions do not change. 15 11/24/2020 SB 5 a and d

DESCENT WITH MODIFICATION 16 16 11/24/2020 SB 5 a and d

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WHY DO WE LOOK DIFFERENT FROM OUR ANCESTORS? The principle of common descent states that “all species, living and extinct, - were derived from common ancestors. ” Over long periods, natural selection produces organisms that have different structures. Each species has descended with changes from other species with time. As a result, species today look different from their ancestors. 18 11/24/2020 SB 5 a and d

THE PROCESS OF EVOLUTION BY NATURAL SELECTION Survival of the Fittest Individuals not suited to their environment either die. Individuals that are better survive and reproduce Over time natural selection results in changes in the inherited characteristics of a population. These changes increase a species’ fitness in its environment 19 11/24/2020 SB 5 a and d

Natural Selection/ Survival of the Fittest Recognize that: -Natural Selection brings about changes over a long period of time (in this case several generations) -Example: - Although the green beetles are reproducing because they are being eaten by the birds, over a long period of time, they have become extinct - The green beetles have a low level of fitness while the orange beetles 20 have a high level of fitness 11/24/2020 SB 5 a and d

EXAMPLE OF NATURAL SELECTION Peppered Moth 1. Moths were either pale or black 2. Pale moths held an advantage over the black moths as the perched on the pale trees 3. Trees became blackened (Industrial Revolution); black moths were now better camouflaged 4. Over time black moths were naturally selected to survive and became far more numerous in urban areas than the pale variety 21 11/24/2020 SB 5 a and d

EXAMPLE OF NATURAL SELECTION 22 11/24/2020 SB 5 a and d

WORDS TO KNOW Fitness is the ability of an organism to survive and reproduce in its specific environment An Adaptation is any inherited characteristic that increased an organisms chance of survival Adaptations Can Be: Physical Speed, Camouflage, Claws, Quills, etc. Behavioral Solitary, Herds, Packs, Activity, etc. 23 11/24/2020 SB 5 a and d

NATURAL SELECTION ON EXISTING VARIATION Natural selection acts on phenotypes, rather than genetic material itself. New alleles are NOT made by natural selection, they occur by genetic mutations. Can only act on traits that already exist. Changing Environment Drought in 1977 suddenly reduced the amount of small, soft seeds that the finches preferred. There were plenty of large, tough shelled seeds. The large beaked finches were able to crack open the seeds increasing their fitness whereas the small beaked finches were not. Adaptations as Compromises Some structures may take on new functions. Ex: Pandas “thumb” 11/24/2020 SB 5 a and d 24

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REVIEWEVOLUTION BY NATURAL SELECTION CONCEPTS The Struggle for Existence (compete for food, mates, space, water, etc. ) Survival of the Fittest (strongest able to survive and reproduce) Descent with Modification (new species arise from common ancestor replacing less fit species) Remember: Natural Selection Cannot Be Seen Directly It Can Only Be Observed As Changes In A Population Over Many Successive Generations 26 26 11/24/2020 SB 5 a and d