Transcript Darwin
Darwinian Evolution The change of populations over time. Genetic variation So why is there such a variety of life? Evolution When Populations of living things slowly adapt and change over time Does not explain origin of life Evolution theory is a way to show the connection of all life forms Evolution also explains the variety within a kind Ex. Types of cats Origin of Species Where did all the species come from? Macroevolution The formation of new taxonomic groups Kingdoms to species Microevolution Variations within a “type”genus or group Speciation Formation of a new species A species is a population of similar organisms that can reproduce and produce fertile offspring Historical context Carolus Linnaeus 1707-1778 Father of modern taxonomy (classification) Binomial nomenclature genus species Canis Lupus James Hutton - 1788 – Profound change is the product of slow, continuous processes “The present is the key to the past” Ex. Mountains grow slowly now so they always grew slowly! Gradualism Jean Baptiste Lamarck 1744-1829 Evolution through acquired traits Based on fossils, relics or impressions of dead organisms Sedimentary rock, ice, tar, amber Charles Darwin 1809-1882 Evolution by natural selection Also cited fossil evidence Anticipated that intermediates would be found Travelled extensively to observe diversity of life Published “origin of species” In 1859 Evolutionary theories Lamarck VS Darwin Lamarck Individual organisms change. These changes are passed on to offspring Ex Giraffes – stretched their necks to get food and passed longer necks on to offspring Darwin Said species change by Natural Selection. Survival of the fittest. The ones best naturally adapted to survive, have more offspring and pass on the traits to those offspring Darwin’s version of giraffes Some giraffes were born with longer necks and better able to get food. These ones survived and passed longer necks to their offspring Darwin’s big adventure! He sailed around the world He sailed on the Beagle No, Not that beagle!!!!!!! HMS Beagle This one Darwin observed There was a change in diversity as he sailed. There was more diversity close to equator which became less as he sailed toward poles Galapagos islands Darwin’s most famous observations He studied lots of interesting creatures in Galapagos seals, tortoises, iguanas and blue footed boobies Especially finches Darwin’s Finches Finches on different islands developed type beaks due to natural selection according to type of food available. better beaks survived better Finches finch – Seed eater Small tree finch – Insect eater Woodpecker finch – Tool user Ground Lamarck and finches What would he say? Individual finches beaks grew differently to adapt to the food source, this trait was passed on Comparison summary – individual changes to adapt to environment. Passes changes to offspring Lamarck – Certain individuals born with advantages, and passes them to offspring Changes due to random variation and mutation Darwin Darwin or Lamarck? A sea turtle that has more webbing on its feet can swim better and catch more food and survives to have lots of offspring Darwin Darwin or Lamarck? A rabbit living in arctic has a lighter color coat and hides better from the wolf, survives to have offspring better Darwin Darwin or Lamarck? A squirrel grows longer claws to grab tree branches better to keep from falling and when it has offspring, they are born with longer claws to grab branches Lamarck Darwin or Lamarck? Darwin or Lamarck? Similarities of Darwin and Lamarck Both Darwin and Lamarck believed changes were due to environmental pressure and changes (lack of food, shelter, mates etc) Geographic isolation When 2 groups are separated they can have different environments causing natural selection Ex. The flying lizards (genus Draco) of Southeast Asia. Differ in size according to location Darwins “Origin of Species” 2 main points 1) Descent with modification 2) Natural selection – Descent with modification Slight changes can occur from one generation to the next Called gradualism Punctuated equilibrium – Changes occur suddenly (an alternate model that explains lacking fossil evidence) Natural selection A differential success in reproduction caused by an interaction between the environment and the phenotypes of a population Environment selects for favorable traits Artificial selection The breeding of domestic plants and animals Traits are SELECTED by scientists Examples of natural selection 1) Evolution of drug resistance in HIV virus and bacteria Antibiotics “select” for resistant mutations 2) Peppered moth Moths adapt to pollution on tree bark better camouflaged (dark moths) survive Problem: peppered moths do not rest on tree trunks! Evidence for evolution 1) Homologies – Homologous structures Structural resemblance that indicates possible evolutionary relationship of species Ex. Bat wing, cat leg Analogies- Analogous Structures that are similar function but not related species. Do NOT indicate evolutionary relationship. Called Convergent evolution Ex. insect wing, bird wing and bat wing Analogies or homologies Analogy Analogies or homologies Homology Cauliflower and broccoli are genetically engineered mustard flowers Analogies or homologies Homology (distant) Analogies or homologies Analogy Analogies or homologies Homology Analogies or homologies 2) Vestigial structures Structures that have little or no use in an organism. (historical remnants) Ex. Whales and snakes with vestigial hip bones 3) Embryological Homologies Haeckel (1874) all vertebrate classes pass through an identical evolutionarily conserved "phylotypic" stage Proved NOT true Actual photographs 4) Molecular Homologies Similar DNA and Proteins DNA is used more now to determine evolutionary relatedness Convergent evolution When two non related species develop the same structure Fish – The most simple of vertebrates Orca – a mammal. Thought to have evolved from land mammals Divergent evolution When two species have a common ancestor and therefore have common structures Ex. Polar Bear and grizzly bear both had a bear type ancestor