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Exam 4 - Coggle Diagram

- - - - Homologous chromosomes: same size, shape, genetic info
      - One from each parent
    - - Independent assortment ( Metaphase 1&2)
        
        Random chromosome orientation
        
        2⁴⁶ combinations in humans
      - Crossing Over (Prophase I)
        
        Synaptonemal complex
        
        New allele combinations via chiasmata
      - Sexual Reproduction
        
        New allele combos from two parents
        
        Promotes heterozygosity
        
        Benefits: genetic diversity, removal of harmful alleles, host-parasite defense
        
        Pollination: cross vs self
  - - - Dominance: dominant vs recessive alleles, homozygous/heterozygous
      - Segregation: alleles separate during meiosis; one per gamete
      - Independent Assortment: genes on different chromosomes sort independently
    - - One Trait
      - Punnet square
      - Genotypical & Phenotypical ratios
    - - Two traits
      - Shows Independent Assortment
      - 9:3:3:1 Ratio
  - - - Intermediate phenotype (e.g., red + white = pink)
    - - More than two alleles at a gene locus
    - - Point (single base)
      - Chromosomal: deletion, duplication, inversion, translocation, transposons
    - - Only 2 gamete types
    - - Multiple genes → single trait
      - Continuous variation (e.g., height, skin color)
  - - - One gene affects expression of another
      - Example: petal color in digitalis
    - - Genes close together on chromosome
      - Parent genotypes more common than recombinants
    - - One gene → multiple phenotypic effects (e.g., wheat awns)
  - - - Autopolyploid: self-fertilization error
      - Allopolyploid: interspecies mating + chromosome doubling
    - - Wheat (tetraploid, hexaploid)
      - Strawberry (chemically induced tetraploid)
    - - Masks harmful alleles
      - Allows for mutation accumulation
      - Seen in seed plants and angiosperms
- - - - All alleles in a population
      - Individuals must be same species, able to interbreed
    - - Formula: copies of allele ÷ total alleles
      - Example: 30 brown alleles out of 50 = 0.6
    - - Formula: # of a specific genotype ÷ total individuals
      - Example: 4 homozygous dominant out of 25 = 0.16
  - - - Alleles: p + q = 1
      - Genotypes: p² + 2pq + q² = 1
    - - p² = homozygous dominant (RR)
      - 2pq = heterozygous (Rr)
      - q² = homozygous recessive (rr)
    - - No mutation
      - No migration (gene flow)
      - No natural selection
      - No genetic drift (very large population)
      - Random mating
  - - - Source of new alleles
      - Must occur in gametes to be inherited
    - - Random allele loss in small populations
      - Bottleneck Effect: population shrinks suddenly (e.g., disaster)
    - - Mate choice (e.g., pollinator behavior)
      - Sexual selection (male-male competition, female choice)
    - - Movement of alleles in/out
      - Influences: environment, life history, speciation
  - - - Heritable traits increase fitness → more offspring
      - Changes allele frequencies over generations
    - - Human-directed breeding (e.g., crops like Brassica)
    - - Alleles affect protein function
      - Advantageous proteins increase survival/reproduction
  - - - Favors one extreme
      - Mean trait value shifts
    - - Favors average trait
      - Reduces variation
    - - Favors both extremes
      - Increases variation
- - - - Exponential (J-curve): unlimited resources
      - Logistic (S-curve): levels off at carrying capacity (K)
      - Equations;
        
        Exponential: dN/dt = rN
        
        Logistic: dN/dt = rN(1 - N/K)
    - - Overshooting leads to die-offs
    - - r-selected: many offspring, weedy, fast growth
      - K-selected: fewer offspring, stable environments
  - - - Includes: age (x), survivors (Nx), survival rate (Sx), survivorship (lx), fecundity (Fx), and age-weighted fecundity
    - - R₀: Net reproductive rate
        
        R₀ > 1 = growth; R₀ < 1 = decline
      - G: Mean generation time = age-weighted fecundity ÷ R₀
      - r: Intrinsic growth rate = ln(R₀) / G
    - - Type I: Low early mortality (humans)
      - Type II: Constant mortality (birds)
      - Type III: High early mortality (plants, fish)
  - - - Stress: Low resources, growth inhibitors
      - Disturbance: Herbivory, pathogens, fire, wind
      - Three Types:
        
        C: Competitors
        
        S: Stress-tolerators
        
        R: Ruderals (weeds)
  - - - Mutualism (+/+): Pollination
      - Commensalism (0/+): One benefits, other unaffected
      - Amensalism (0/-): One harmed, other unaffected
      - Competition (-/-): Shared limited resources
      - Predation (+/-): Herbivory, parasitism
    - - Species living and interacting in same area
      - Influenced by abiotic and biotic factors
  - - - Prey: dN/dt = rN - aNP
      - Predator: dP/dt = faNP - qP
      - Variables
        
        r: prey growth rate
        
        a: predator attack rate
        
        f: efficiency of converting prey to predators
        
        q: predator death rate
    - - Prey grows exponentially
      - Predator population rises
      - Prey declines due to predation
      - Predator declines due to lack of food