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Evolution. Chapter 16. Early Theory of Evolution Lamarck, a French biologist, proposed: T hat body structures could change according to the actions of the organism. Acquired characteristics could be passed on to any offspring. He was incorrect, but paved the way for Darwin. .

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Chapter 16


Early Theory of Evolution

  • Lamarck, a French biologist, proposed:
    • That body structures could change according to the actions of the organism.
    • Acquired characteristics could be passed on to any offspring.
    • He was incorrect, but paved the way for Darwin.
developing the modern theory of evolution
Developing the Modern Theory of Evolution
  • @Charles Darwin published ideas on how species evolved and they became the basis of modern evolutionary theory@;
    • He took a job as a naturalist on the HMS Beagle where he traveled to South America and the Galapagos Islands collecting samples of specimens
    • He made many observation and after further experimentation he proposed the process of natural selection.
darwin s observations
Darwin’s observations:
  • Finches and tortoises had different beaks and shells/necks depending on diet.
  • However, all the finches and all the tortoises have many similar physical characteristics suggesting a common ancestor for each.
  • The differences in the finches and tortoises was due to adaptation to the food source.
natural selection
Natural Selection
  • @Survival of the fittest, those individuals better suited to survive@
    • Darwin wrote “ On the Origin of Species by means of Natural Selection”, after years of observations and studying evidence he collected on the mechanism of change.
  • 4 principles of Natural Selection:
      • Variation
      • Heritability
      • Overproduction
      • Reproductive advantage
  • @Is cumulative changes in groups of organisms through time.@
  • Natural selection is not evolution but it is the mechanism by which it occurs.
5 types of evidences of evolution
5 Types of Evidences of Evolution
  • Fossils - Recorded for Earth’s history.
5 types of evidences of evolution1
5 Types of Evidences of Evolution
  • Anatomy
        • Homologous structures – Similar structures, Different use or function.
        • Analogous structures – different structure but are similar in function.
        • Vestigial structures – a body part structure that has no function in a present day organism but was useful to an ancestor. (ex human appendix)
5 types of evidences of evolution2
5 Types of Evidences of Evolution
  • Chemistry – reveals relationships between organisms, species, and individuals.
    • Using RNA and DNA.
5 types of evidences of evolution3
5 Types of Evidences of Evolution
  • Embryology – through development of a tail and gill silts can be seen in embryos of birds, reptiles, and mammals.
5 types of evidences of evolution4
5 Types of Evidences of Evolution
  • Distribution – geographical distribution
extra credit question
Extra Credit Question

What is this fish’s name and what TV show is it from?

Blinky. The Simpsons

  • @A trait shaped by natural selection that increases an organisms reproductive success.@
      • Mimicry – is a structural adaptation that enables one species to resemble another; predator may avoid them if they look harmful.
      • Camouflage – an adaptation that enables species to blend with their surroundings.
population genetics
Population Genetics
  • Populations evolve not individuals.
  • Natural selection acts on poor phenotypes that will not benefit the survival of the organism.
  • Genes in the population are called gene pool.
5 mechanisms of evolution1
5 Mechanisms of Evolution
  • Genetic drift – change in frequency of gene variations in a population.
      • Founder’s effect reduction in alleles resulting from a small group settling in a separate location away from the rest of the population.
      • Bottleneck effect is a reduction in alleles resulting from a chance event that drastically decreases population size.
5 mechanisms of evolution2
5 Mechanisms of Evolution
  • Genetic flow – migrating individuals transport genes.
5 mechanisms of evolution3
5 Mechanisms of Evolution
  • Non-random mating – organism mate with individuals in close proximity.
  • Mutation – change in genetic material.
extra credit quote
Extra Credit Quote

Mutation, it is the key to our evolution. It has enabled us to evolve from a single-celled organism into the dominant species on the planet. This process is slow, and normally taking thousands and thousands of years. But every few hundred millennia, evolution leaps forward.

–Professor X (X-Men 1)


-Dr. Jean Gray (X-Men 2)

5 mechanisms of evolution4
5 Mechanisms of Evolution
  • Natural Selection acts on variation – “Survival of the fittest”
  • Types of Natural selection
    • Stabilizing selection – favors average individuals.
    • Directional selection – favors one extreme or the other, example very large or very small.
    • Disruptive selection – favors individuals of both extremes.
    • Sexual selection – changes in

frequencies of traits based on

ability to attract mates.

  • Speciation – evolution of new species.
      • Allopatric speciation – physical barrier divides a population into 2 or more population.
      • Sympatric Speciation – a species evolves into a new species without physical barriers.

Reproductive isolation occurs when formerly interbreeding organisms can no longer mate and produce fertile offspring.

    • Prezygotic isolation – prevent fertilization
      • Geography
      • Behavioral
      • Mating time
      • Physical differences
    • Postzygotic isolation – when fertilization occurs, prevent hybrid organism from reproducing. (sterility)
patterns of evolution
Patterns of Evolution
  • Adaptive radiation (Divergent evolution) – when ancestral species evolve into an array of species to fit number of diverse habitats.
    • patterns in which similar species become increasingly different.
patterns of evolution1
Patterns of Evolution
  • Convergent evolution – patterns of evolution in which distantly related organisms evolve similar traits.
      • Due similar environmental pressures.
rate of speciation

Gradualism is the idea of that species originating through a gradual change of adaptation.

Punctuated equilibrium is rapid speciation, in burst with long periods of genetic equilibrium in between.

Rate of Speciation