Evolution

• Evolution is the genetic change in a population or species over time

  • Descendants that are different from their ancestors
• A population is a group of individuals of the same species in an area
• What did Charles Darwin do?

  Darwin was the first person to talk about HOW evolution occurs
• Fossils are most often found in layers of sedimentary rocks - compressed sand

  • Under specific pressures
  • Simple organisms are found in lower layers than the more complex organisms
• Prokaryotic Cells are simple than Eukaryotic Cells

  • They would be more likely to be in the greatest depth of sedimentary rocks
• Prokaryotic Cells are older and deeper in sedimentary rocks
• DNA carries genetic information

  • passed onto offspring
  • codes for proteins required to survive
  • Grow and reproduce
  • Determines characteristics
• Differences in DNA results in differences in components of proteins (amino acids) produced (hemoglobin protein)
• Darwin found individuals to be varied within a population by

  • environmental factors
  • heritable traits that benefit individuals to be most successful (produce the greatest amount of offspring)
• Evolution at different levels

  • Microevolution - Evolution of a population
  • Macroevolution - Evolution on a large scale
  • Speciation - Evolution of a new species
• Darwin was the first person to talk about how evolution occurs

  • Population in that moment in time
  • Bird is eating the lighter beetles and lower the population
  • Over time, the survivors reproduce and reduce, or even eliminate the other coloured beetles
• Fossils are most often found in layers of sedimentary rocks (compressed sand)

  • Under specific pressures
  • Simpler organisms are found in the lower layers than more complex organisms
• Prokaryotic

  • Only contains DNA
  • Does what it does and does not increase in size
• Eukaryotic: True nucleus

  • Contains organelles that each have their own functions
  • Increase in size
• Prokaryotic Organisms

  • Domain Bacteria
  • Domain Archaea

  Weird organisms are found in places that no other organisms can survive
• Eukaryotic Organisms: Domain Eukarya

  • Kingdom Animalia
  • Protists
  • Plants (Kingdom Plantae)
  • Kingdom Fungi
• Biogeography

  • Darwin knew about groupings and used his evidence to support his theories
  • Biogeography was used to compare the organisms to other organisms in neighbouring and/or farther lands further support his theory
• Comparative Anatomy

  • Homologous Structures of Mammals
  • Similar forelimb structures but are different due to different functions required
• Comparative Embryology

  • Human vs. Chick Embryos
  • Pharyngeal pouches and tail are found in all vertebrate embryos
• What is microevolution?

  Microevolution is a change in a population's gene pool over generations
• What is a population?

  A population is a group of the same species living in the same geographic area
• What is a gene?

  A gene is a unit of hereditary information containing a specific nucleotide sequence in DNA/RNA
• What is an allele?

  An allele is an alternate version of a gene that determines an organism's appearance and features
• What can cause microevolution to occur?

  1. Natural Selection
  2. Genetic Drift
  3. Geneflow
  4. Mutation
• Sexual Reproduction does not result in change in allele frequencies but does not result in variation
• Conditions required for Hardy-Weinberg Equilibrium

  1. Very large population
  2. Isolated population (no gene flow between populations)
  3. No mutation
  4. Random mating
  5. Equal reproductive success (no natural selection)
• Two effects in Genetic Drift

  1. Bottleneck Effect: Event
  2. Founder Effect: Colonization
• Gene Flow

  • Addition/loss of alleles in a population can alter allele frequencies
  • Results in increased similarity between neighbouring populations
• Mutation

  • Any mutant is rare
  • Creating a new allele is very rare, has little effect in single generation
  • May be important in long term since ultimate source of genetic variation
• Non-Random Mating

  Many species reproduce by random mating (assumption met) BUT certain species choose mate(s)

  Change in mating behaviour unlikely to change between generations (possibly long term)
• Natural Selection requires genetic variation between individuals

  Increased genetic variation with increased number possible allele combinations for a trait 

  • Alleles in blood
  • Phenotype that is dependent on many genes

  Can result in different phenotypes (morphs) of a characteristic → polymorphic population
• Natural selection acts on PHENOTYPE (so indirectly on genotype → alleles); only assumption that can lead to adaptive  changes in allele frequencies

  • Three different easy phenotype altered
• The three types of natural selection

  1. Directional Selection: Evolution of a phenotype in a particular direction (increased frequency of one allele over another)
  2. Stabilizing Selection: Intermediates of phenotypes selected for (against extremes)
  3. Disruptive Selection: Extremes of phenotypes selected for (against intermediates)
• How does Genetic Variation Occur?

  1 - Mutation: The ultimate source of genetic variation

  2 - Sexual Recombination: Type of selection that acts phenotypes which help animal mate (note term: sexual dimorphism)

  • Intrasexual Selection
  • Intersexual Selection
• If natural selection favors one phenotype over another (and therefore genotype), how is variation maintained in a population (what prevents unfavorable genotypes from disappearing from the population)?
• There are three main reasons for evolution occurring

  1. Genetic Drift → Event
  2. Gene Flow → How close are other populations
  3. Natural Selection → What’s in the environment
• Macroevolution is evolution on a larger scale that relies heavily on geologic data and fossils

  • Continental Drift
  • Mass Extinction
  • Adaptive Radiation
• Continental Drift is the moving of tectonic plates relative to one another
• Mass Extinctions are random events that act on species indiscriminately

  • Ends with holes of species
  • Leads to adaptive radiation
• Adaptive Radiation is a period of rapid evolution of many new species from a common ancestor