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Evolution…. There is nothing constant in the universe, all ebb and flow, and every shape that is born bears in its womb the seeds of change. -Ovid Genetic Diversity is… Variety of genes in a population Brought on by change, mutation or evolution Evolution is… Change of an organism over time Can be genetic, physical, metabolic, etc. How did the debate of evolution begin? HMS Beagle Take a trip in 1831 Charles Darwin (pg 394) Naturalist Amazed by diversity of life What is diversity? Studied anatomy The World News in 1831 Earth’s Earth’s Populatio Population n Exceeds Its Exceeds Product Product! Could it be true? Knew that species reproduce more offspring then necessary. Why? Not all survive. Why? A struggle exists. What kind? Which ones are selected for survival/reproductio n? Fitness All organisms have traits, traits that vary throughout the population. Fitness is the ability of an organism to survive and reproduce (pass their genes on) http://www.techapps.net/interactives/pepperMoths.swf Selection Artificial selection Farmers use this technique to breed particularly desired traits If farmers select, why can’t nature? Natural selection Survival of the fittest Manner of change that occurs when organisms with favorable traits for their environment survive and reproduce So who does nature select for? Organisms that have qualities that make an organism successful or an organism that has qualities that make an organism unsuccessful? Pg 395 HUGE DEAL!!! Before Darwin, people believed that the Earth and everything on it remained unchanged. Darwin was suggesting that new species changed slowly over time from pre-existing organisms. English Peppered Moth http://www.techapps.net/interactives/pepperMoths.swf Scientist studied in industrial areas And rural areas Usually white rural Black is favored industrial Why? Fitness was the answer! Black moths were more fit in industrial areas Pollution Coal burning (blackens trees) White moths were favored in rural areas Adaptation Physical and behavioral traits that enable an organism to survive and reproduce Types Structural Adaptations Changes in “body” parts Tailbone Thorns on a rose Horse Hoof Physiological adaptations Changes in metabolism Ancestors of the horse walked on spread-out toes, a useful trait for walking on the soft, moist grounds of primeval forests. As grasses began to appear, diets shifted from foliage to grasses, thus leading to larger and more durable teeth. At the same time, horse's needed to be capable of greater speeds in order to outrun predators. This was attained through the lengthening of limbs and the lifting of some toes from the ground in such a way that the weight of the body was gradually placed on one of the longest toes, the third (thus the lost of the minor digits) Structural adaptations Mimicry-organism copies appearance of another species Plant or Animal? Mimicry Monarch or Viceroy? Owl moth Structural Adaptation Camouflage-organism blends in with the surroundings Camouflage Camouflage PS lab on page 398 Rate of Adaptation Depends on the type of adaptation and rate of reproduction Physiological adaptations Changes in metabolism EXN Science Wire... Daily news from the world of science. Penicillin usually kills all bacteria, but now…. Fighting antibiotic-resistant bacterial Pg 399 www.unitedstreaming.com Bacteria Fight Back Bacterial resistance http://www.pbs.org/wgbh/evolution/educ ators/lessons/lesson6/act1notes.html Resistant to Round-up? Darwin’s Finches Darwin Collected birds He thought he had various types Closer inspection suggested that they were all finches Skeletal and DNA Each had own adaptations Why? (success) What is a species? A species is a group of organisms that look alike and can interbreed (making fertile offspring) Speciation Generation of a new species (occurs only when interbreeding or the production of fertile offspring are prevented) Pg 409 Physical barriers Volcanoes split populations as lava flows Sea level changes can equal water level barriers Geographic isolation Physical barrier separates a population into groups At first, organisms are the same Then organisms begin to change (adapt) and their gene pool changes, therefore creating a new species Reproductive Isolation Formerly interbreeding organisms are prevented from producing fertile offspring DNA is so different that fertilization can’t happen Chromosome # differs Behavioral One group of frogs mates in fall, other in summer Order of events Geographic isolation Reproductive Isolation Speciation Visual of Speciation The creation of a new species challenges scientists to ORGANIZE Cladogram Chart Demonstrates how organisms relate to one another over long/complex history of change(s) Reconstructs evolutionary change(s) Cladogram Evidence for Evolution Fossils Anatomical Studies Functionless structures Embryo development DNA (5) DNA Same genes, different function 100% Chimps 90% Sheep 71% Snails 57% Parsnip (4) Embryo development Similarities in structure In early development, we all have tails and gill slits Which is the human? (3) Functionless Structures Vestigial structures Example: wings of flightless birds, the limb girdles of snakes, and the ear muscles of humans Why do vestigial structures continue to be inherited? Answer Common ancestors did use them and speciation hasn’t occurred far enough to eliminate them completely Vestigial or Not? Appendix? (located on the lower right hand side of the abdomen) Was thought to function in filtering waste and other materials Now… Purpose of appendix believed found The function of the appendix seems related to the massive amount of bacteria populating the human digestive system. There are more bacteria than human cells in the typical body. Most are good and help digest food. But sometimes the flora of bacteria in the intestines die or are purged. Diseases such as cholera or amoebic dysentery would clear the gut of useful bacteria. The appendix's job is to reboot the digestive system in that case. Whale (2) Anatomical Studies (pg 401) Do these forelimbs look similar? Homologous structure Skeleton is the same in structure but NOT in function (homologous structure) Example: Bone structure of a bird wing and a human arm Bird Wing and Human arm (pg 401) Anatomical Studies Suggests common ancestor with same basic structure Over time, ancestor moved into different environments so structures were used for different functions because of different needs for survival Analogous Structure If structures are similar in function, but NOT in structure (analogous structure) Do not suggest a common ancestor Examples: Bird wings and butterfly wings Analogous Structures http://www.fieldmuseum .org/evolvingplanet/prec ambrian_14.asp Is there proof? As the physical processes of Earth changed, rock was constantly formed and destroyed Oldest rocks are 3.9 billion years old Fossils (1) Fossils Evidence of an organism that lived long ago Paleontologists Study fossils to tell a story (CSI) Fossil teeth can indicate the size of an animal, how they moved, and what they ate Fossils like Figure 14.1 (pg 371) could suggest ideas on climate PS lab pg 372 How do fossils form? Figure 14.3 on page 373 http://www.fieldmuseum.org/evolvingpla net/cambrian_14.asp Dating a fossil () Figure 14.2 on page 372 Relative dating Radiometric dating Radioactive isotopes in rocks Unstable Atoms that break down in predictable ways. Based on these, an age can be obtained for a fossil Similar to what you see in CSI when an autopsy is done and age is determined by presence of wisdom teeth, growth plates, etc. Geographic timeline Timeline of Earth’s history Divisions are based on organisms that lived during that time Mass extinctions lead to a new division or era A period of time where a large group of organisms DISAPPEARS from the fossil record Eras Precambrian Cyanobacteria Prokaryotes only at first At the end of the era, the first eukaryotes appear AND multicellular eukaryotes like sponges and jellyfish Paleozoic Worms, sea stars, arthropods (oceans) Fish appear Early seed plants Amphibians and reptiles Eras Mesozoic Mammals appear Cenozoic (Your Era) Small and mouse-like Dinosaurs Birds at the end of this era Flowering plants Continental drift Mammals began to flourish Primates appear Humans (1) Fossils Fossil record is full of skeletal remains that seem to be changing Camel Whale (land dwelling, dog-like) How? (page 402) http://www.pbs.org/wgbh/evolution/educato rs/teachstuds/unit3.html Fossil record suggests a geological timeline 4.5 Billion years ago…. What happened? Suggested that the Earth formed Primitive Earth did not have… It did not have oxygen It did not have an ozone It did not have any life What changed? Earth was very hot Volcanoes spewed lava and gas (relieving some of Earth’s core pressure) Gases help create original atmosphere Next… Earth began to cool and water vapor condensed = rain Lightning brought nitrogen to the “soil” Series of suggested events Atmosphere changes Organic molecules form Molecules organized into proteins, carbs, lipids and NAs Cells appear (protocells, then prokaryotes, then eukaryotes) Protocell-Chains of AA linked together=membrane; able to complete some basic functions (make ATP, PS without ribosomes) Endosymbiont theory Endosymbiont Theory First eukaryotes came from prokaryotes? How? Page 385 (figure 14.15) Symbiotic Relationship Choroplasts and mitochondria have: Their own DNA Ribosomes Ability to reproduce on their own Biogenesis: Life comes from life However, how did life begin on Earth? So far, no one has yet to scientifically prove how life on Earth began. Several theories exist The fossil record suggests that the earliest organisms were… Prokaryotes What are those? They appeared 3.5-4 billion years ago For food, they used organic molecules What are organic molecules? Eventually, the food will run out! So… Evolution generates… Organisms that can make their own food First form of competition (between producers and consumers) The Earth Changes… As photosynthetic bacteria increase, so does the amount of OXYGEN With OXYGEN comes the OZONE OZONE blocks UV and increases the amount of LIFE that can survive on EARTH (more evolution) Next to appear were… Eukaryote organisms 1-2 billion years ago Sequence of life was… Bacteria Protist Fungi Plants and Animals (seem to overlap) Sequence of animal life was… Fish Amphibians Reptiles Mammals What about us? Have we evolved? How fast do new species form? Gradualism (Darwin believed in this) Idea that species originate through gradual buildup of new adaptations Camels Horses Another idea was Punctuated equilibrium The idea that speciation occurs in bursts (rapid) with long periods of stability in between Elephant Mechanisms of Evolution Populations evolve;individuals don’t Changes in genetic equilibrium equal evolution Natural Selection Populations evolve; individuals do not Gene pool-entire collection of genes in a population Allele frequency-percent of a particular allele in a population Genetic equilibrium-allele frequency doesn’t change from generation to generation (so no evolution) Changes in genetic equilibrium equal evolution Mutation-change in the gene pool (DNA change) Most are harmful and selected against in a population = no change, but sometimes a mutation is selected FOR and = a change Genetic Drift-change in allele frequency by chance in a species (small populations are more impacted) How can you change genetic equilibrium? Cause the allele frequency to change How do you change an allele frequency? Move organisms in and out of a population (gain or lose genes) “Altering the gene pool” (Discussion) What Darwin couldn’t explain Darwin knew that changes occurred in a population (evolution), but he couldn’t prove HOW they were happening genetically. What scientist genetically proved Darwin’s theory of evolution with the discovery of genes and alleles? Gregor Mendel Natural Selection (acts on a population) Selects which organisms pass their genes on so allele frequency changes from one generation to another Types of Natural Selection (pg 408) Stabalizing selection Directional selection Disruptive selection Stabalizing selection Selection favors “average” individuals resulting in a decrease of variation in a population Example: Human babies Stabalizing Selection Directional selection Selection favoring individuals with extreme forms of a trait Can equal rapid evolution of a population Example: Finches and their bird beak Directional Selection Disruptive selection Selection favors individuals at both ends of extreme forms of a trait Eliminate the intermediate Can equal evolution of TWO new species Example: Insects that mimic vs. a random insect Disruptive Selection Patterns of Evolution Adaptive Radiation Divergent Evolution Convergent evolution Adaptive radiation (pg 412) Process of evolution of an ancestral species into an array of species that occupy different niches (Newly evolved species evolve into different species very fast) Hawaiian Creepers What could cause adaptive radiation? Geographic isolation Happens on Islands a lot Form of Divergent evolution Divergent Evolution Pattern of evolution in which species that once were all similar to the ancestor become more and more distinct (same become different) (become less and less alike due to changes base on environmental needsn.s.) Adaptive radiation is A form of divergent evolution Example of Divergent Evolution Darwin’s Finches Hawaiian Creepers Convergent Evolution (pg 413) Pattern of evolution in which distantly related organisms evolve similar traits Different become similar Happens when unrelated organism occupy similar environments and face similar selection pressures Convergent Examples Dolphins and fish Swim in a streamlined environment Convergent Examples Birds, bats and insects Fly Convergent Examples Woodpeckers and opossums How they obtain food Critical Thinking Hummingbird moths are night-flying insects whose behavior and appearance are similar to those of hummingbirds. Explain how these two organisms demonstrate convergent evolution. Skill Review Biologists discovered two squirrel species living on opposite sides of the Grand Canyon. They hypothesize that the species evolved from a common ancestor. What observations or experiments could provide evidence for this hypothesis? What geographic isolation event could have started it all? Another theory associated with evolution is how/where did life come from. Origin of life Spontaneous Generation Idea that nonliving materials could produce life Observation: Every year in the spring, the Nile River flooded areas of Egypt along the river, leaving behind nutrient-rich mud that enabled the people to grow that year’s crop of food. However, along with the muddy soil, large numbers of frogs appeared that weren’t around in drier times. Conclusion: It was perfectly obvious to people back then that muddy soil gave rise to the frogs. Observation: In many parts of Europe, medieval farmers stored grain in barns with thatched roofs (like Shakespeare’s house). As a roof aged, it was not uncommon for it to start leaking. This could lead to spoiled or moldy grain, and of course there were lots of mice around. Conclusion: It was obvious to them that the mice came from the moldy grain. Disproving the theory Redi’s experiments Pg 380 Figure 14.10 Pasteur’s experiments Pg 381 Figure 14.11