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Lamarck vs. Darwin

Lamarck vs. Darwin. Introduction to change in organisms. What is a theory?. The most probable explanation for a large set of data based on the best available evidence Summarizes a hypothesis or group of hypotheses that have been supported with repeated testing.

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Lamarck vs. Darwin

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  1. Lamarck vs. Darwin Introduction to change in organisms

  2. What is a theory? • The most probable explanation for a large set of data based on the best available evidence • Summarizes a hypothesis or group of hypotheses that have been supported with repeated testing

  3. What is a species?What is a population? • Species – group of a single type of organisms that interbreed and are reproductively isolated • White-tailed deer • Population– refers to a group of organisms of a particular species living in a certain area. • White-tailed deer on Mt. Nebo

  4. Lamarck’s Theory • Jean Baptiste Lamarck: 1800’s • Believed: • Change Occurs Over Time • inheritance of acquired characteristics • acquired changes were passed to offspring • Law of Use and Disuse • If a body part was used, it got stronger • If body part NOT used, it deteriorated • Examples: Body builders or pierced ears

  5. Lamarck’s Theory of Evolution • Giraffes all had SHORT necks originally • Giraffe’s Necks got LONGER from stretching for food • “Acquired” trait (long necks) then passed to offspring • Giraffe population became long-necked

  6. Lamarck’s Theory of Evolution • More examples • Traits Acquired During Ones Lifetime Would Be Passed To Offspring Clipped ears and tails of dogs could be passed to offspring!

  7. Think Back to the bell work question… What is the difference between acquired traits and inherited traits? Which category would the length of a giraffe’s neck fall under? Which category would a dogs clipped ears or tail fall under? Why? What is the real difference between these traits? Think about science and biology.

  8. Lamarck’s Mistakes • Was he correct?? • NO! • Traits are passed down from one generation to the next by GENES, not by an individual’s life experiences or activities • 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

  9. Voyage of the Beagle Charles Darwin • Born Feb. 12, 1809 • Joined Crew of HMS Beagle, 1831 • Naturalist • 5 Year Voyage around world • Astounded By Variety of Life

  10. Voyage of the Beagle 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

  11. Darwin’s Belief’s • Survival of the fittest OR natural selection • Food and resources are limited • So organisms have to COMPETE to get them (lions fight for food, space, mates …) • OVER PRODUCE too many organisms • Not all offspring will survive only the MOST FIT (not always the biggest or strongest!)

  12. What happened to the giraffe’s? • Survival of the fittest or natural selection • Natural selection said the giraffes with short necks had less food to eat • Why? • the food resources changed to leaves only on the upper branches • What happened? • short necks could not reach upper branches and did not survive (couldn’t pass on genes) • Long neck giraffes survived & reproduced because they were able to reach the food

  13. Life is good. I never want anything to change. The trees are getting taller & we aren’t. We need to stretch our necks to reach the food Lamarck I am so glad Junior here doesn’t have to go through the stretching because he was born with a long neck  MUST KEEP STRETCHING!!

  14. Darwin vs Lamarck Pick an animal not discussed in class. Make a comic strip (min. 4 panels each) of the following: Show how your animal may have evolved by way of Lamarck’s hypothesis of acquired traits. Show how this same animal may have evolved by way of Darwin’s hypothesis of natural selection. Make sure to color your comic strip & that it is neat & clearly depicted (use rulers for your panels).

  15. Evidence of Evolution Fossil Records Molecular Records (Carbon Dating and DNA) Embryology Anatomical Records

  16. Fossil Records • Fossils are the preserved remains, tracks, or traces of once-living organisms • Robert Hooke in 1668- 1st to propose that fossils are the remains of plants & animals. • Provides the most direct evidence for macroevolution

  17. Missing Links Ardi (Ardipithecus ramidus) : stood about 47 inches tall and weighed about 110 pounds. Took 15 years to unearth. Lived 4.4 million years ago Lucy (Australopithecus afarensis) : 40 % complete skeleton. Lived 3.2 million years ago

  18. Fig. 13.4 Whale “missing links” • Fossils have been found linking all the major groups • The forms linking mammals to reptiles are particularly well known

  19. More Missing Links Archaeopteryx. The most primitive known bird. Lived ~150 million years ago. Ambulocetus: The walking whale. This animal could walk as well as swim. It lived ~50 million years ago.

  20. Fossil Records Relative Dating (aka Law of Superposition) by Nicolaus Steno

  21. Molecular Records Certain atoms are known to decay (break down) at a specific rate. Scientists can look at these atoms to determine how old an organic object is. Radioactive isotope 14C- gradually decays over time back to 14N (known as Carbon Dating) It takes ~5600 years for half of the 14C present in a sample to be converted to 14N. This length of time is called the half-life. Half life (t1/2): the time needed for half of the atoms of the isotope to decay For fossils older than 50,000 yrs scientists use other isotopes such as, potassium isotope t1/2 of 40K = 1.3 billion years to turn to argon (40Ar)

  22. Molecular Record • New alleles (genes in DNA) arise by mutations and they come to predominance through favorable selection • Thus, evolutionary changes involve a continual accumulation of genetic changes • Distantly-related organisms accumulate a greater number of evolutionary differences than closely-related ones

  23. Fig. 13.5 Molecules reflect evolutionary divergence The greater the evolutionary distance The greater the number of amino acid differences

  24. Embryology • Similar structural forms can be seen in early stages of development of different organisms.

  25. Relict developmental forms Anatomical Record • Similar structural forms can be seen in various living organisms • Ex: Homologous structures, Analogous structures and Vestigial structures • All vertebrates share a basic set of developmental instructions

  26. Homologous structures: Have same structure but not necessarily the same function. They are all derived from the same part of a common ancestor. • As vertebrates have evolved, the same bones are sometimes put to different uses, yet they can still be seen, their presence betraying their evolutionary past.

  27. Analogous structures: Structures of different species having similar or corresponding function but not from the same evolutionary origin • (Different animals adapt in similar fashion when challenged by similar opportunities) • The feature has the same function but looks different. They are the result of convergent evolution

  28. Vestigial structures: • Although they had a purpose & function in the past they are largely or entirely functionless now. • a vestigial structure may retain lesser functions or develop new ones. The blind mole rat has tiny eyes completely covered by a layer of skin. The blue whale has tiny hind leg bones under its tail.

  29. Evolution is the slow, gradual change in a population of organisms over time… a looooooooong time!

  30. What determines survival? • Natural Selection • Adaptations (traits) that help individuals survive • survive predators • survive disease • compete for food • compete for territory • traits that help individuals reproduce • attracting a mate • compete for nesting sites • successfully raise young

  31. PATTERNS OF EVOLUTION Coevolution: Change of two or more species in close association with each other. EXAMPLE: Bumblebees and the flowers they pollinate have co-evolved so that both have become dependent on each other for survival.

  32. Convergent Evolution:organisms that are very similar but are not closely related. This happens because of a change within the environment. Analogous structures are the result of convergent evolution.

  33. DIVERGENT EVOLUTION:Two or more related species that become more dissimilar due to different environments. • This usually produces another species EXAMPLE: GALAPAGOS FINCHES

  34. Artificial Selection: Creating unnatural characteristics by breeding species to promote a certain type of offspring. EXAMPLE: Domestic dogs German Shorthaired Pointer German Shorthaired Pointer Lab (AKA:Rocco) Chocolate lab

  35. EVOLUTIONARY FORCES • Five evolutionary forces can significantly alter the allele frequencies of a population • 1. Mutation • 2. Migration • 3. Genetic drift • 4. Nonrandom mating • 5. Selection

  36. Mutation • The ultimate source of new variation • Errors in DNA replication and change in DNA due to extraneous factors • Mutation rates are too low to significantly alter allele frequencies on their own

  37. Migration • Movement of individuals from one population to another • Immigration: movement into a population • Emigration: movement out of a population A very potent agent of change

  38. Genetic Drift • Random loss of alleles • More likely to occur in smaller population • Founder effect • Small group of individuals establishes a population in a new location • Bottleneck effect • A sudden decrease in population size to natural forces

  39. Nonrandom Mating • Mating that occurs more or less frequently than expected by chance • Inbreeding • Mating with relatives or self • Increases homozygosity • Outbreeding • Mating with non-relatives • Increases heterozygosity

  40. Selection • Some individuals leave behind more offspring than others • Artificial selection • Breeder selects for desired characteristics • Natural selection • Environment selects for adapted characteristics

  41. Fig. 13.3 Evolution in the titanotheres Large blunt horns Small bony protuberance Hoofed mammals

  42. Example of Natural Selection • A classic example of natural selection is the Peppered moths during Industrial Revolution in Europe

  43. Forms of Selection • Selection is a statistical concept • One cannot predict the fate of any single individual • But it is possible to predict which kind of individual will tend to become more common in a population • Three types of natural selection have been identified • Stabilizing selection • Acts to eliminate both extreme phenotypes • Disruptive selection • Acts to eliminate intermediate phenotypes • Directional selection • Acts to eliminate a single extreme phenotype

  44. Fig. 13.12 Three kinds of natural selection

  45. Fig. 13.13 Stabilizing Selection Increase in the frequency of the intermediate phenotype • Acts to eliminate both extreme phenotypes • In humans, infants with intermediate weight at birth have the highest survival rate • In chicken, eggs of intermediate weight have the highest hatching success

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