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• Friday…wear comfortable clothes to go outside!! • Permission slips needed for Friday as well • TODAY: – Work on model…comp lab 618 around • Darwin and the Beagle: http://www.sciencechannel.com/tv-shows/greatestdiscoveries/videos/100-greatest-discoveries-darwinsstory/ • Bird Mating Dance: https://www.youtube.com/watch?v=wCzZj21Gs4U • Spider Mating Dance: https://www.youtube.com/watch?v=V8-CbmM8pf8 • 10 top weird mating dancing: – https://www.youtube.com/watch?v=kxuijR_KdPg • Write the equation for photosynthesis. – 6CO2 + 6H2O ------> C6H12O6 + 6O2 Agenda: -Warm-Up -Collect lab homework -Evolution video clips -Evolution stations notes -Socrative review game • Write the equation for cellular respiration. – C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy • In which organelle does photosynthesis occur in? – chloroplast • In which organelle does cellular respiration occur in? – mitochondria • Go to the website below: – m.socrative.com • The classroom you are joining is: – CINO Choose your color and begin the review • For MUCH of history, people believed: – Frogs developed from falling drops of rain – Mice arose from sweaty underwear • Spontaneous generation is the incorrect hypothesis that nonliving things are capable of producing life • “All living beings come from seeds of the plants or animals themselves” • However, if someone were to demonstrate even 1 exception to this hypothesis, then Redi’s hypothesis would be rejected. • John Needham’s experiment involved placing a broth into a bottle, heating it and then sealing it. • Days later, Needham found the presence of life, and eventually announced that life had been created from nonliving material. • This supported the incorrect idea that life could come from nonliving things. What he did: 1st experiment Boiled flasks with broth (chopped hay in water) Sealed the flasks after boiling (airtight) What he found: There was NO bacterial growth in the flasks with airtight seals What he did: •Used swan-necked flasks •Flasks allowed in air, but trapped dust (and microbes) in the curve because they couldn’t overcome gravity •Boiled broth to force the air out •Broke the necks off of some of the curved flasks • Descent with Modification • the slow , gradual change in a population of organisms over time Charles Darwin • Born Feb. 12, 1809 • Joined Crew of HMS Beagle, 1831 • 5 Year Voyage around world • Avid Collector of Flora & Fauna • Astounded By Variety of Life • During His Travels, Darwin Made Numerous Observations And Collected Evidence That Led Him To Propose A Revolutionary Hypothesis About The Way Life Changes Over Time • Patterns of Diversity were shown • Unique Adaptations in organisms • Species Not Evenly Distributed • Australia, Kangaroos, but No Rabbits • S. America, Llamas • Production of more individuals than can be supported by the environment leads to a struggle for existence among individuals • Only a fraction of offspring survive each generation • Survival of the Fittest • Individuals who inherit characteristics most fit for their environment are likely to produce more offspring than less fit individuals • Called Natural Selection • The unequal ability of individuals to survive and reproduce leads to a gradual change in a population, with favorable characteristics accumulating over generations (natural selection) • He believed that new species evolve • Darwin’s process of natural selection has four components. – Variation. Organisms (within populations) exhibit individual variation in appearance and behavior. These variations may involve body size, hair color, facial markings, voice properties, or number of offspring. On the other hand, some traits show little to no variation among individuals—for example, number of eyes in vertebrates. – Inheritance. Some traits are consistently passed on from parent to offspring. Such traits are heritable, whereas other traits are strongly influenced by environmental conditions and show weak heritability. – High rate of population growth. Most populations have more offspring each year than local resources can support leading to a struggle for resources. Each generation experiences substantial mortality. – Differential survival and reproduction. Individuals possessing traits well suited for the struggle for local resources will contribute more offspring to the next generation. • Malthus (If human population grows unchecked, there will be insufficient space and food for everyone. Darwin applied this thought to animal and plants.) • Lyell (Geologist who instilled in Darwin knowledge of how Earth changes, which influenced how Darwin thought about life changing.) • Wallace (Publishing his own thoughts on evolution pushed Darwin to do the same.) • Jean-Baptiste Lamarck, 1809 • One Of First Scientists To Understand That Change Occurs Over Time • Stated that Changes Are Adaptations To Environment acquired in an organism’s lifetime • Said acquired changes were passed to offspring • Idea called Law of Use and Disuse • If a body part were used, it got stronger • If body part NOT used, it deteriorated • Blacksmiths & Their Sons (muscular arms) • Giraffe’s Necks Longer from stretching) • Inheritance of Acquired Characteristics • Proposed That By Selective Use Or Disuse Of Organs, Organisms Acquired Or Lost Certain Traits During Their Lifetime • These Traits Could Then Be Passed On To Their Offspring • Over Time This Led To New Species Clipped ears of dogs could be passed to offspring! • Lamarck Did NOT Know how traits were inherited (Traits are passed through genes) • Genes Are NOT Changed By Activities In Life • Change Through Mutation Occurs Before An Organism Is Born • Some scientists believe Earth is about 4.6 billion years old • Lightening, volcanoes, meteorites, and UV light made conditions intolerable for life • Atmosphere was also toxic All life forms from common ancestor First organisms primitive, unicellular type Energy sources broke the gas molecules and simple organic compounds formed Simple molecules washed into oceans and made larger ones What makes molecules organic???? Theory of Chemical Evolution: The formation of complex organic molecules from simpler inorganic molecules through chemical reactions in the oceans during the early history of the Earth. • Primitive pre-cells were combination of polypeptides, nucleotides, and carbohydrates • Could not use energy or reproduce • Source of DNA unknown • Required outside energy source to reproduce • Similar to present day bacteria Autotrophs – capable of making own food Developed when food supply became scarce Photosynthetic organisms evolved from these autotrophs Photosynthesis produced the oxygen for future organisms Oxygen production formed Ozone for atmosphere Blocked UV rays, many new organisms could evolve • a group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding. • Geographic Isolation: The physical separation of members of a population. This can happen when an original population’s habitat is divided by a geographic barrier that can’t be crossed. • Allopatric Speciation: when species arise as a result of geographic isolation. “different homelands” • Reproductive Isolation: The inability of members of a population to successfully interbreed with members of another population of the same or related species. • Can occur because of pre-fertilization (different mating seasons, inability to recognize mating call, incompatible anatomy, etc.) or post-fertilization isolation (offspring doesn’t fully develop or is sterile). • Sympatric speciation: occurs when two subpopulations become reproductively isolated within the same geographic area. Changes in Earth’s landscape leads to and influences how the organisms change… Catastrophism: The belief that the Earth has been affected in the past by sudden, short-lived, violent events, possibly worldwide in scope (great floods, rapid mountain formation, etc.). Uniformitarianism: The idea that slow incremental changes, such as erosion, create the Earth's appearance. Both have contributed to appearance of Earth today… Punctuated Equilibrium: Pattern of evolution where there are long, stable periods of equilibrium (no change) interrupted by brief periods of more rapid change. When would we see this??? (May occur when a small population becomes isolated from the main population, or when a small population migrates to a new environment and organisms evolve to fill new niches, for example. May follow sudden drastic change to environment or mass extinctions where there are new niches to fill.) Gradualism: Pattern of evolution where change is slow, steady, and consistent. Supported by pattern of many fossil records. It seems that both patterns occur, depending on the situation… • Also called migration — is any movement of genes from one population to another. • Includes lots of different kinds of events, such as pollen being blown to a new destination or people moving to new cities or countries. • If genes are carried to a population where those genes previously did not exist, gene flow can be a very important source of genetic variation. • One of the basic mechanisms of evolution. • In each generation, some individuals may, just by chance, leave behind a few more descendents (and genes, of course!) than other individuals. • The genes of the next generation will be the genes of the "lucky" individuals, not necessarily the more fit individuals • Genetic drift affects the genetic makeup of the population but, unlike natural selection, through an entirely random process. So although genetic drift is a mechanism of evolution, it doesn't work to produce adaptations. • Founder Effect – occurs when a new colony is started by a few members of the original population. This small population size means that the colony may have: – reduced genetic variation from the original population. – a non-random sample of the genes in the original population. • severe reduction in population size due to intense selective pressure or a natural calamity (hunting, hurricane, etc.) which alters the allele frequency. If all green beetles are squashed by chance, the allele frequency will be shifted to more brown. • Speciation is the formation of new species as a result of evolution. • Isolation is the key component needed for speciation to occur • Directional Selection – Natural selection favors one extreme of the population for that trait – often happens when environment changes in a consistent waye.g.climate gets colder. • Disruptive Selection – Natural selection favors both extremes selected – Causes species to diverge • Stabilizing Selection – Natural selection favors the average for population selected • Sexual Selection • Neck of Giraffe • Antibiotic resistance of bacteria • Moth color (melanin) • Camouflage/Mimics • Many sexually selected traits • When the extremes of the trait aren’t as well suited Examples • bird clutch size • Elk Antlers size • Giraffe neck length • Tail length in birds • Causes divergence within the species • Occurs when two different types of resources in one area • Results in specialization for each branched group • May lead to formation of new species • E.g. Darwin’s Finches • Fossils are direct or indirect remains of organisms preserved in media such as sedimentary rock, amber, ice, or tar. Fossils have been found that indicate organisms existed well over 3 billion years ago. These organisms were simple, single-celled organisms. About a billion years ago, increasingly complex multi-cellular organisms began to evolve. • The higher up you go in an undisturbed rock stratum (rock layer), the younger the rock layers become and therefore it is believed the fossils within these layers, as compared to lower rock layers, are also younger. • When comparing fossils in undisturbed strata, fossils can be found in upper strata which, although different from fossils in lower strata, resemble those fossils. This suggests links between modern forms and older forms, as well as divergent pathways from common ancestors.