Transcript Evolution
What is Evolution? Evolution- the genetic change of populations over time Population- group of organisms of the SAME species that occupies certain area Species- organisms that can interbreed and produce FERTILE offspring – Ex) populations in Sauerman Woods Crown Point -whitetail rabbits -sparrows -deer -squirrels Liger (lion and tiger)-infertile Cama (camel and llama)-infertile How Do We Know Populations Evolve? Population Sampling- technique uses part of population to represent whole population Capture 100 random rabbits – These rabbits are a representation of all the rabbits in the area. – We can study many things within this group… Genetics of the Population… Gene Pool- all of the genes of every individual in population sample Frequency- how often something occurs Population genetics involves studying the frequency with which certain alleles occur in a population’s gene pool In 50 years, will the allele frequencies be the same? Hardy-Weinberg • Hardy-Weinberg Equilibrium Principle – frequencies of the dominant and recessive alleles in a population change in time due to 5 things: • Mutations • Migration • Natural selection (survival of fittest) • Small population • Non-random mutation • If these things occur, then the frequencies change and a population evolves History of Evolutionary Thought Before 1850, most people believed… – Earth formed by supernatural events and never changed – Earth only a few thousand years old – Each species was made to fit its environment – Species never changed and did not go extinct Early Scientists’ Ideas Darwin deserves credit for the Theory of Evolution as we know it today He was not the first to come up with the idea: – Carl Linnaeus proposed a new system of organization for plants and animals based on their similarities (noticed relationships) – Erasmus Darwin considered how organisms could evolve through mechanisms such as competition – Jean-Baptiste Lamarck presented evolution as occurring due to environmental change over long periods of time Carl Linnaeus Developed a classification system for the huge variety of living things he found – Wrote book Systema Naturae in 1735 to reveal his classification system – My closet! – There are currently 1.9 million species that have been identified using his method – Linnaeus’s system of classification reflects evolutionary relationships Jean Baptiste Lamarck – – – – A French naturalist who proposed that populations of species evolve His idea proposed: Changes in an environment cause an organism’s behavior to change, leading to greater use or disuse of a structure or organ The organism would pass on these acquired changes to its offspring, so a species would change in time Idea called “Evolution by inheritance of acquired characteristics” Wrong on several accounts Charles Darwin At 22, was invited to sail on the “HMS Beagle” – Was going to school to be a minister-believed God created each species to match its habitat and they never changed – Thought Earth was about 6,000 years old and didn’t change, just like everyone else Darwin’s Observations One place of note that he visited was the Galapagos Islands During journey, he made observations and recorded them in a journal Darwin observed fossil and geologic evidence supporting an ancient Earth Darwin’s Finches When Darwin traveled to the Galapagos he took interest in the finches He noticed the finch species on the islands were different, but all resembled one from S. America Darwin thought some migrated and new species evolved Darwin’s Finches This is what Darwin proposed: – Finches migrated from South America to the islands – Populations on different islands adapted to different environments and food sources they found – Those that could survive passed on their genes – Those that couldn’t survive perished Darwin’s Finches Over time different mutations accumulated in the different finch populations on the different islands The populations diverged, or became more and more different from each other Darwin’s Finches The populations on the islands became so different they no longer mated if they met Several new finch species evolved from a common ancestor from S. America This is an example of macroevolution Recent finch research Speciation Geographical isolation- members of a population are separated geographically – Major step that leads to speciation – Due to volcanoes, earthquakes, flooding, etc. – Can lead to divergence and then speciation Artificial Selection Artificial selection- human intervention in animal or plant reproduction to ensure that certain desirable traits are passed on Instead of NATURE selecting which traits are favorable, HUMANS selectively breed those animals with favorable traits Ex. dogs or racehorses Darwin bred pigeons to explore this idea Darwin’s Results In 1859, Darwin published The Origin of Species His book stirred up controversy Idea called “Evolution by natural selection” Darwin Video Darwin’s Book Explained Natural Selection Natural selection- organisms best suited to their environment survive and reproduce – – – Darwin’s proposed mechanism of evolution Survival depends on the particular environmental conditions a species finds itself in—nature! If the environment changes, so do the populations that live there Adaptation- using inherited genetic characteristics to increase chance of survival in new environment Natural Selection and Salamanders Natural Selection Three conditions necessary for natural selection to occur: – Genetic variation: Individuals within a population must be genetically different ****Random mutations are the raw material for evolution to occur!!!!!!! – Overproduction of offspring: More organisms are born than can survive – Differential reproduction: Certain traits enable individuals to survive and have more offspring than others Result of Natural Selection - Genes that help a population survive in their conditions stay in their gene pool, while “unfavorable” genes gradually decrease in frequency - This causes changes in the genetics of populations EVOLUTION!!!!! - As new mutations accumulate over a long time, the new populations no longer can mate with the original they started as. New species have formed! - Natural Selection Animation Whose idea for evolution is this? What We Know Now Evolution is a Scientific Theory Not a hypothesis, or an educated guess, or a “theory” in layman’s terms Unending amount of evidence to support it and NONE to reject it Evolution is called “the unifying principle of Biology” Isn't Evolution JUST a Theory? Types of Evolution Evolution - genetic change of a population of organisms over time descent with modification Microevolution: Small genetic changes of a population Shorter amount of time Bengal tiger simulation was microevolution Types of Evolution MACROevolution-When new species are formed over long periods of time – Due to tremendous amounts of accumulated genetic changes in a population – Speciation- formation of new species due to accumulated microevolution and mutations How does macroevolution work? dibosirdsaur GEOGRAPHIC ISOLATION dibosirdsaur dibosirdsaur 10 million years of accumulated mutations diosirdsaur ibosirdsaur 10 million years of accumulated mutations diosirdsaur iboirdsaur 10 million years of accumulated mutations dinoirdsaur boirdsaur 10 million years of accumulated mutations dinordsaur boirdsur 10 million years of accumulated mutations dinodsaur boirdsu 10 million years of accumulated mutations dinodsaurs boirds 10 million years of accumulated mutations DINOSAURS BIRDS EVOLUTION by natural selection Microevolution Changes in gene frequencies in a population Shorter times Examples: Peppered moth and Bengal tiger MACROevolution Accumulated microevolution and mutations to form whole new species Longer times Examples: Darwin’s finches and geographical isolation Evidence for Evolution Three types of evidence: – Fossils – Anatomical – Molecular Fossil Evidence • Fossils- any traces of dead organisms – – – – dinosaur bones insects trapped in tree sap leaf impressions footprints Fossil Evidence • Transitional species- species that have been found in the fossil record that are intermediates between two other species in the evolutionary process – – Radiometric dating- a dating technique that measures amount of radioactive material in a rock or fossil Relative dating- a dating technique that estimates the date of a fossil by relating it to the age of the layers of rock around it Fossil Evidence • To fossilize an organism must be buried by sediment – In swamps, mud, tar pits, or the ocean bottom – Hard stuff fossilizes (bones, nails) – Radiometric and relative dating are used to find out how old the fossil is Relative Dating Radiometric Dating Fossil Evidence • Fossils show: – – Life has been around for millions of years Transitional species link older to newer species – Darwin proposed the idea of transitional species, though he had no evidence – Today we have evidence: • Archaeopteryx • Tiktaalik Fossil, etc. • Whales Fossil Evidence-Archaeopteryx WINGS BEAK Fossil Evidence • Whales--60 million years of evolution – Descended from 4-legged wolflike animals that were also ancestors to cows and horses – Fossil evidence shows slow loss of legs – Pelvis still remains with no rear legs Anatomical Evidence • Anatomical evidence- evidence for evolution which is based on similarities and differences between the physical structures of different species. • What can we tell about the relatedness of the three species below? Anatomical Evidence • Homologous structures-Bone structure the same (homo) but not function –Bird wing, dolphin fin, and a human arm –Function these structures is not the same! –Show that these species shared a common ancestor –Similar structures resulted from accumulated mutations and modifications Homologous Structures Anatomical Evidence • Analogous structures- Bone structure different but serve the same function –Function = flight –Butterfly wing, bat wing, fly wing –These structures, although they have the same function, are not built the same! –Show different species evolved structures with similar function through different evolutionary pathways –EVOLUTION IS NOT RANDOM! Anatomical Evidence Anatomical Evidence • Vestigial structuresstructures that no longer serve a function • These structures are the remnants of an evolutionary past and show common anatomy with other species Molecular Evidence • Molecular evidenceevidence concerning the comparison of DNA and protein molecules between species • Ultimate tools for scientists studying evolution • Same genetic basis for all organisms: A, C, T, and G shows we are all related Molecular Evidence • Mutations and sexual reproduction are a cause of variation in a species’ DNA • DNAmRNAprotein – Transcription- copying the DNA code into mRNA – Translation- converting the code of mRNA into a long chain of amino acidsprotein – Differences in DNA are seen in differences in protein and therefore, traits Molecular Evidence • Species with more similar DNA are more closely related on the evolutionary tree – Less time since they split to accumulate mutations (and, therefore, differences) – Common ancestorany species in the past from which two or more related species has evolved – Evidence for Evolution = speciation event = mutation • Earth is estimated to be about 4.6 billion years old • Atmosphere was harsh – Very Hot – Lots of water vapor – Volcanoes – NO BREATHABLE OXYGEN GAS! – CO2, ammonia, methane present Finding Evidence of Early Life Stromatolites Scientists had hard time finding evidence of early life 45 years ago we found out why…. Most ancient life was microscopic=microfossils in stromatolites 1st organisms to evolve were prokaryotes Oldest microfossil3.5 billion years old!! Cyanobacteria fossil about 1,000,000,000 (1 billion) years old found in stromatolites How did life begin? 1.)Extraterrestrial origin 2.)Creation—”divine forces” 3.)From non-living matter (“Chemical Evolution”)-Organic compounds assembled creating 1st bacterial cell Early Earth’s atoms and molecules Life’s Chemicals: Proteins, Lipids, Carbs, Nucleic Acids First Prokaryotic Cells Origin of Life’s Chemicals Miller-Urey Experiment Hypothesis: Can organic compounds form in early Earth conditions? Experiment recreated atmosphere of early Earth Results: building blocks of life were formed Amino acids (proteins) Nucleotides (DNA, RNA) Lipids Carbohydrates Origin of Life’s Chemicals The first genetic material was RNA Earth’s early surface was inhospitable due to immense UV radiation that destroys nucleic acids Deep sea vents may have provided sheltered location for nucleic acids, as well as life, to evolve Oldest living prokaryotes found there today… RNA can form under conditions similar to deep sea vents Life’s Chemicals: Early Earth’s Proteins, atoms and Lipids, Carbs, molecules Nucleic Acids Miller Urey and deep sea vents First Prokaryotic Cells Origin of Cells • Some molecules can spontaneously form into droplets and hollow spheres • Solution with lipids and proteins will self assemble into a lipid bilayer like a cell membrane • First cell membrane and beginning of prokaryotic life took 1 billion years Life’s Chemicals: Early Earth’s First Proteins, atoms and Prokaryotic Lipids, Carbs, molecules Cells Nucleic Acids Miller Self Urey and assembly and deep sea 1 billion vents years Road to Modern Organisms 1st life was bacteria unicellular prokaryotes Cyanobacteria- photosynthetic blue-green prokaryotes later changed Earth’s atmospherereleased O2! 2nd was unicellular eukaryotes Endosymbiotic Theory 3rd was multicellular eukaryotic organisms Endosymbiotic Theory—3min How Modern Day Biologists Classify • • • • • 1. Comparing anatomy (physical traits) 2. Looking at genetic similarities & differences 3. Biochemical make-ups 4. Behavioral similarities Origin of Life Video Cladograms • Cladogram- a branching diagram that shows evolutionary relationships • We use taxonomy – the science of classifying living things, to help us determine the cladogram Writing Scientific Names • Binomial nomenclature- unique 2-word Latin naming system used by scientists • 1st word is the genus, 2nd is the species – Genus is always capitalized – Species is always lower case – The whole name is underlined if written or italicized if typed • Example: Homo sapiens: – Homo = genus – sapiens = species – Common name = humans Scientific Naming Examples • Genus- group of organisms that share similar characteristics • Species- group of organisms that can successfully breed within their group, but not others – Panthera leo-lion – Panthera pardus-leopard 6 Kingdoms • There are six kingdoms all living things are classified into: – Animals – Plants – Fungi – Protists – Eubacteria – Archeabacteria Classification • Scientists have determined seven levels of classification: – Kingdom = Kings – Phylum = Pass – Class = Classes – Order = to Order – Family = Families – Genus = and their Good – Species = Sons around Classification of Modern Humans • • • • • • • Kingdom = Animalia Phylum = Chordata Class = Mammalia Order = Primates Family = Hominidae Genus = Homo Species = sapiens Evolution of Primates • Primate- mammal with 5 flexible fingers • Earliest dwelled in trees-arboreal and evolved special adaptations for this: • Opposable thumb….Why? • Binocular vision- eyes in front of head in which field of vision of eyes overlap—depth perception….Why? • Rotating Shoulders 2 Types of Primates • Primates are divided into 2 groups: 1. prosimians and 2. anthropoids • Prosimians- nocturnal primates that were the first to evolve – i.e. Loris and Bush Baby – 30-40 million year fossils show they were common – Nighttime hunters…How can you tell? 2 Types of Primates • Anthropoids- day active primates – – – – – Monkeys, apes, and humans Smaller eyes Color vision Larger brains Replaced prosimians rapidly 2 Types of Primates • Anthropoids—3 categories – Monkeys • Have tails • Old World—Asia and Africa • New World—Central and S. America – Apes • NO TAILS • Larger brains than monkeys • Chimps, gibbons, orangutans, bonobo, etc. – Humans • Our closest genetic primate relative is? Evolution of Humans • Vocab: – Bipedal- walk upright on two legs – Hominid- bipedal primates such as humans and their closest fossil relatives Hominids • Hominids are the ONLY bipedal primates: – Locking knee joints – Spine enters skull at bottom of head – Femurs (thigh bone) tapers in – Big toe in line with others Laetoli Footprints Hominid vs. Chimpanzee • Chimps most closely related primate to humans— 95% similarity in the sequence of our genes! • Differences: – Human’s jaw arc shaped with smaller canines; chimps’ are U shaped with larger canines and larger gaps. Hominid vs. Chimpanzee – Hominid spine S– chimps’ is C shaped – Hominid pelvis is bowl-shaped, chimps’ long – Hominid thigh bones taper in—chimps’ out – Human Evolution Video Clip Early Hominids • Darwin’s Descent of Man – 1871 – African apes are close genetic relatives of modern humans – Said fossilized remains of ape and human common ancestor should be found in Africa Early Hominids • Genus Australopithecus A. afarensis • Genus Homo Time Homo habilis Homo erectus Homo sapiens NOT A COMPLETE LIST! THERE ARE OTHERS! Australopithecus • Genus Australopithecus – LucyAustralopithecus afarensis – Fossil found in Africa – They were hominids • Shape of pelvis and femurs showed they were bipedal. • Locking knee joints – Short—3’6’’ – Brain size of chimps – Jaws more rounded than apes – Teeth like humans LUCY • • • • 3.5 million years old 40% complete Female Showed us: – Walked upright first – Brain size grew LATER. SKULLS A. afarensis (Lucy) Homo sapien • SKULLS Lucy had a small skull like an ape, but she wasn’t one LUCY APE APES Homo sapiens transitional species Homo erectus Homo habilis Australopithecus afarensis common ancestor to ape and H. sapiens Homo habilis • Means: “handy man” • Small structure like Lucy • Skull 2X’s the size of Lucy • 2- 1.8 mya in Africa • Tools made of bone and stone Homo erectus • • • • • • Peking man Africa / Asia / Europe Larger than H. habilis Larger brain Excellent tools, used fire 1.5 mya – “immediate” ancestor Where Did H. sapiens evolve? • Out of Africa hypthothesis- idea like Darwin’s which states H. sapiens evolved IN Africa and spread to H..sapiens rest of world • Out of Africa hypothesis H. erectus supported by fossils of modern-like humans found in Africa Early H. sapiens • Homo neanderthalensis discovered in Neander Valley in Belgium • Massive skulls and protruding brows • 400,000-100,000 years ago Early H. sapiens Great controversy: did they die off (genes no longer) or did they interbreed with us so their genes are still in our gene pool? Modern H. sapiens probably evolved in Africa and replaced Neanderthals. Mated???? APES Homo neanderthalensis transitional species Homo sapiens Homo erectus Homo habilis Australopithecus afarensis common ancestor to ape and H. sapiens Recent Discoveries • 2009 Recent analysis of Ardipithecus ramidus… aka “Ardi” found in 1994 – A hominid with opposable big toes like chimps and apes – 1.2 million years OLDER than Lucy, and our oldest known common ancestor with other primates (4.4 mya)! – 47 inches tall – Show that chimps have actually evolved MORE than humans since our common ancestor Mated???? APES Homo neanderthalensis transitional species Homo sapiens Homo erectus Homo habilis Australopithecus afarensis common ancestor to ape and H. sapiens ARDI????? Evolution Summary • The Theory of Evolution by Natural Selection holds the high status of near certainty: it’s a scientific theory • There are no observations of life, living or extinct, that evolution cannot explain • Why is evolution controversial anyway?