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Download Chapter 16 Evolution and Adapations
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Evolution Biological Evolution Modern humans (Homo sapiens) appear about 2 seconds before midnight Age of reptiles Insects and amphibians invade the land Plants invade the land Age of mammals Recorded human history begins 1/4 second before midnight Origin of life (3.6–3.8 billion years ago) Fossils become abundant Fossils present but rare Evolution and expansion of life Evolution The gradual change in the genetic makeup of a population or species overtime Fossil Record • Most of what we know of the history of life on earth comes from fossils (Stephen Gould). • Gives us physical evidence of organisms. – Show us internal structure. • Uneven and incomplete record of species – We have fossils for 1% of species believed to have lived on earth. – Some organisms left no fossils, others decomposed, others have yet to be found. • Other info from ancient rocks, ice core, DNA. 4 major mechanisms that drive evolution: • Natural Selection- “Survival of the fittest” • Mutations- Change in the gene structure due to an outside influence • Gene Flow- migration into or out of a population of new genetic variations to an existing population • Genetic Drift- changes in the genes over time Unifying Principles of Evolution • Perpetual Change: All species are in a continuous state of change or Evolution. Unifying Principles of Evolution Nature- The combined influences of physical and biological limiting factors acting upon an organism. Natural Selection The process by which populations change in response to their environment as individuals better adapted to the environment leave more offspring. Individual that possess superior physical, behavioral, or intellectual attributes are more likely to survive versus those who have less of these characteristics. Natural Selection Natural selection is driving process of evolution through the accumulation of inherited changes over time. Adaptation • An organisms ability to respond to change • May be structural (how they are built), behavioral (how they act), or physiology (how they function in life). Example: Fish eyes are larger deeper in ocean or even bioluminescent for those at the bottom Bird beak size to change feeding habits based on food types, Migration of birds south, Homologous structures, camouflage. The Case of the Peppered Moths Adaptation • Industrial revolution –Pollution darkened tree trunks • Camouflage of moths increases survival from predators • Natural selection caused a shift away from light-gray towards dark-gray moths Fig. 18.5, p. 287 Fox Adaptations Make a list of the adaptations a fox would have to make to have the best chances of survival if one fox species lives in the Arctic and the other species lives in the Tropics. Arctic Fox Tropics Fox Fox Structural Adaptation Northern population Early fox population Spreads northward and southward and separates Arctic Fox Different environmental conditions lead to different selective pressures and evolution into two different species. Southern population Gray Fox Adapted to cold through heavier fur, short ears, short legs, short nose. White fur matches snow for camouflage. Adapted to heat through lightweight fur and long ears, legs, and nose, which give off more heat. Avian Dinosaurs: Birds Based on taxonomy classification, all birds evolved from dinosaur ancestors. Archaeopteryx is believed to be the link of birds with dinosaurs. Dinosaurs are REPTILES. Figure 06A & B: Archaeopteryx Reproduced from Heilmann, G. The Origin of Birds. Appleton, 1927 (Reprinted Dover Publication, 1972) How did birds have to adapt to move away from the dinosaur classification to the classification of BIRDS? What had to evolve for birds to fly? 1. Feathers had to evolve from scales. 2. Bones became hollow to reduce weight 3. Strong breast muscles for flight 4. Four chambered heart for increased oxygen to muscles The Origin of Feathers • Feathers evolved from reptilian scales for insulation and display – Three major hypotheses for their origin: • Feathers were an adaptation for insulating the (presumed) warm-blooded and grounddwelling reptilian ancestors of birds • Ancestral birds were tree-dwelling reptiles that used their developing wings to glide from branch to branch • Ancestral birds were ground-dwelling runners whose feathers formed planing surfaces increasing their speed Invading the Air: Flying Reptiles • Known adaptations for sustained powered flight have appeared only three times in the evolution of terrestrial vertebrates: in pterosaurs, birds and bats. – Pterosaurs and Pterodactyls Figure 05: Pteranodon © Paul B. Moore/ShutterStock, Inc. Figure 04A: Pterodactyloids Genetic Variation • Provide material for natural selection • Brought about by mutation • Provides genetic diversity –Allows a species to adapt a new niche in its environment • Leads to Natural Selection • Leads to New Species (speciation) Jean Baptiste Lamarck Lamarck believed that if the giraffes’ neck became longer from stretching it could be inherited by their offspring or by not using a trait it could disappear from their offspring. He believed in “acquired characteristics”. This theory is totally untrue. Example baseball player passing his acquired abilities to his son, a boxer passing his acquired skills to his son, or a PHD passing their knowledge to their children. Galapagos Finches • Some 10000 years ago a number of small finches most likely grass quilts made their way from South America 600 miles across the Pacific Ocean to the Galapagos Islands. • Because of the great distance from South America the island was isolated and new species arrive relatively infrequently and when the grass quilts arrived they found a land that was free of completion for them. They developed into many species taking on adaptive beaks to improve their food chances. Galapagos Finches Review • Evolution is driven by Natural Selection or Survival of the Fittest. • Structural Adaptation- long neck, short ears. Behavioral Adaptation- birds and caribou migrating, and animals hibernating. • All living organisms are traced back to a Common Ancestor • Of all the species that have ever lived most are now extinct (99.9%). Review Of all the species that have ever lived most are now extinct (99.9%). Adaptation enhance an organism’s ability to survive and reproduce. With changing tectonic plate locations: 1. Life forms have become extinct 2. New lifeforms have evolved 3. Lifeforms have changed or evolved over time; Speciation Horse Evolution Mnemonic Device Create a Mnemonic device to remember the evolutionary order of Bacteria, Invertebrates, Fish, Amphibians, Reptiles, Insects, and Mammals Bacteria I FARM Extinction True extinction is the elimination of every member of a species. Examples Carrier pigeon, dinosaurs, whooping crane Extinction • Local, mass, and true extinction • The ultimate fate of all species just as death is for all individual organisms • 99.9% of all the species that have ever existed are now extinct Extinction Extinctions open up new opportunities for speciation and adaptive changes. Generally after a mass extinction the species that survive have fewer predators and possibly more food sources thus more chance for their populations to grow quickly and adding diversity to their species. Local extinction- species has disappeared from a local area due to loss of habitat, food, or out numbered by predators. Mass extinction– 25-90% of total species – Five great mass extinctions in which numerous new species evolved to fill new or vacated niches in changed environments (at end of Precambrian, Ordovician, Devonian, Permian[worst of all], and Cretaceous). – 10 million years or more for adaptive changes to rebuild biological diversity following a mass extinction Extinctions • Habitat Disruption – Volcanic Eruptions – Asteroid Impacts – Sea Level Change • Habitat Modification – – – – – Climate Change Mountain-Building Sea Level Change Precipitation Change Toxic Materials • “Exotic” Species Introductions – Continental Drift Extinction in the Context of Evolution IF 1. The environment changes rapidly and 2. The species living in these environments do not already possess genes which enable survival in the face of such change and 3. Random mutations do not accumulate quickly enough then or 4. New predators introduced or major food source lost then All members of the unlucky species may die Extinction The greater the diversity of genotypes and phenotypes among a population the less likely an extinction will occur. Comparative Anatomy Comparative Anatomy includes Homologous, Analogous and Vestigial structures. Comparisons of anatomical features in different organisms often provides evidence to support the theory of evolution. As Organisms are often classed together according to similarities in their structures. Homologous Structures • Homologous structure are structures that share a common origin but may serve different functions in modern species. • These structures are evidence that organisms with similar structure evolved from a common ancestor. • Examples include the forelimbs of a variety of mammals. For example, human, cat, whale and bat. Homologous Structures • These species show the basic same skeletal elements . • However these skeletal elements have been modified over time to suit the different functions suitable for the type of mammal. • Homologous structures result from divergent evolution meaning their ancestral lines started out fairly similar, but evolved along different paths, becoming more different over time. • Structures that are similar due to evolutionary origin, such as the forearm bones of humans, birds, porpoises, and elephants, are called homologous. However, structures that evolve separately to perform a similar function are called analogous. The wings of birds, bats, and insects, for example, have different embryological origins but are all designed for flight. Homologous Structures Birds and Reptiles • Both have scales • Reptile fossils most common to modern birds 5/1/2017 Homologous structures in Cow and Human eyes Humans and cows share homologous structures in the eyes of the iris, cornea, lens, and optic nerve. They are similar structures in two different animals that serve the same purpose. Analogous Structures However, structures that evolve separately to perform a similar function are called analogous. The wings of birds, bats, and insects, for example, have different embryological origins but are all designed for flight. Analogous Structures • Analogous structures are a contrast to homologous structures. • They serve the same function between organisms but are different in internal anatomy. www.encarta.co m Such as the wings of birds and butterflies or the eyes of lobsters and fish. • These structures are of no use in classifying organisms or in working out their evolutionary relationships with each other. Figure 4 Vestigial Structures Bones or other structures that are present in an organism but are reduced in size, have no use or a less prominent function than in other organisms. Examples: the human tail bone(coccyx), wings of the flightless cormorant, wings of an ostrich. Flightless Cormorant Embryonic Development Genotype/Phenotype Genotype- how an organism is made up of the genes from its parents: genetic makeup cannot be seen (ATCGTACGTTACG). Phenotype- how an organism looks: the observable traits of an organism; picture What kind of structures are these What kind of structures are these Aristotle Aristotle (384-322 B.C.) was a philosopher and a naturalist who first tried to group plants and animals into groups based on categories. The Greeks and Romans tried to also classify organisms into basic categories. Carl Linnaeus was the first to really publish a system of classification. He is famous for the use of Binomial Nomenclature. Carl Linnaeus Was a Swedish biologist who became interested in how to classify organisms. The science of classification is called Taxonomy. Carl Linnaeus(1707-1778) introduced the system of binomial nomenclature that used genus and species to identify a organism. Taxonomy Uses 1) helps scientists organize info for identification around the world 2) easy to ID creatures 3) makes it easy to ID new species Taxonomy Major Classifications Broad Narrow Kingdom Phyla Class Order Family Genus Species Create a Mnemonic Device 1-You will have to Know how to place the categories of Taxonomy in Order for the Unit Test 2-Kitchen Patrol Cooks Orders For General Staff 3-Keep Plates Clean Or Families Get Sick 4-Kids Playing Chess Occasionally Fa_ _ Green Slime Genus is always capitalized and species is always lower case. Both are italicized. • • • • Apis mellifera- European honeybee Canis familiaris- Common dog Homo sapiens- Modern man Felinus catus- Cat • Using Genus and Species name is called Binomial Nomenclature Species • A species is a group of organisms that can interbreed and produce fertile offspring. The key is fertile offspring to carry on the species. • Horse and donkey can mate but produce a sterile organism called a mule. • • • • • • • Human Taxonomy Kingdom- Animalia Phylum- Chordata Class- Mammalia Order- Primata Family- Hominidae Genus- Homo Species- Homo sapiens Homo sapiens means “wise man” Killer Whale Taxonomy • • • • • • • Kingdom-Animalia Phyla- Chordate Class-Mammalia Order-Cetacea Family-Delphinidea Genus-Orcinus Species-Orcinus orca Honeybee Taxonomy • • • • • • • Kingdom- Animalia Phylum- Anthropoda Class- Insect Order- Hymenoptera Family- Apidea Genus- Apis Species- Apis mellifera Human DNA is similar to a chimpanzee(98.4%) and to a banana (60%). DNA is becoming the tool for modern scientist to classify organisms with. Geologic Order of Organisms 1- Bacteria- first life on Earth 2- Invertebrates-no backbone 3-Fish-the first vertebrates 4-Amphibians-land and water animal 5-Reptiles-the first true land animal 6-Mammals Mnemonic device= Bacteria I FARM Man’s Greatest Changes Bipedal-walk upright Opposable thumbs- able to grasp and pick up objects Binocular vision-two eyes that focus together for depth vision. Theories on How Life Originated 1.Spontaneous Origin2.Divine Creation3.Extraterrestrial Origin4.Evolution- Spontaneous Origin All things are made up of the same basic elements. Carbon, Nitrogen, Oxygen, and Hydrogen. Through chemical and physical processes life formed in very simple life forms and grew to more complex forms through the billions of years of Earth’s history. Poof; Life just appeared by mixing the elements. Stanley Miller experiments. Divine Creation A divine creator made life out of the elements that were present when Earth formed. Divine creation believes that man was created versus evolving. Extraterrestrial Origin This theory suggests that life was carried to Earth by a meteorite or asteroid and life did not form on Earth at all. A book from the 1970’s called “Chariots of the Gods” discusses Earth being visited by Aliens. Evolution Life formed and evolved through natural selection, adaptations, and mutations to DNA that lead to more and more complex life. Tectonic Plate Movement The greatest event causing diversity in species is the movement of the tectonic plates causing the species to be isolated from each other and thus creating more opportunity for diversity within the species. Tectonic Plate Movement Caused Climate change Isolation of species More opportunity for diversity of species Genotype Genotype is the make up of the genes in an organism that determines it characteristics. Genotype can be changed by mutations that accumulate over time. Phenotype Phenotype is what we see as the characteristics of an organism.