Genetics and Evolution

Mendelian Inheritance
1. Law of Segregation:
  1. alleles segregate independently when forming gametes
2. Law of Independent Assortment
  1. segregation of one pair of alleles is independent to that of another
3. Homozygous
  1. 2 identical alleles
4. Heterozygous
  1. one dominant and one recessive allele
5. Monohybrid Cross
  1. 3:1 Phenotype Ratio
  2. 1:2:1 Genotype ratio
6. Dihybrid Cross
  1. 9:3:3:1 Phenotype Ratio
  2. 16 different genotypes
Pedigree Analysis
1. Autosomal Dominant
  1. not sex linked
  2. affected parent = affected individual
2. Autosomal Recessive
  1. need 2 alleles to inherit disease
  2. not sex linked
3. X Linked Dominant
  1. dominant gene carried on X chromosome
  2. both sexes affected equally
4. X Linked Recessive
  1. recessive X gene on X chromosome
  2. only 1 sex affected
5. Mitochondrial Inheritance
  1. Inherited via mum
  2. all offspring is affected
Gene Interactions
1. Complete Dominance
  1. classic Mendelian inheritance
2. Incomplete Dominance
  1. Heterozygote phenotype is intermediate
3. Co-Dominance
  1. both homozygotes displayed
4. Epistasis
  1. <4 phenotypes
  2. can produce 9 different ratios
5. Variable Penetrance
  1. no. of individuals carrying particular allele
6. Variable Expressitivity
  1. the extent to which a genotype expresses it's phenotype
Linkage and Recombination
1. Incomplete Linkage
  1. 60% parental, 40% recombination
2. closer together = more likely to be linked
  1. further apart = more likely to have double crossovers which can undo first crossover
3. Linkage- Recom. freq <50%
4. Independent Assortment, = 50% recomb freq
Complex Genetic Traits
1. Continuous Variation
  1. variation from one extreme to another
2. Discontinuous Variation
  1. phenotype is one thing or another
3. Variance
  1. Vp = Vg + Ve
    1. Vg = Va + Vd
  2. Additive
    1. each allele contributes to phenotype additivetly
  3. Dominance
    1. either allele can show dominance
  4. Environmental
    1. Environment has effect on variance along with genetics
4. Heritability
  1. Narrow
    1. h2 = Va / Vp
  2. Broad
    1. H2 = Vg / Vp
5. Meristic Traits
  1. polygenic and environ. determination
  2. phenotype expressed as a whole number
6. Threshold Traits
  1. polygenic and environ. determination
  2. 2 states- affected or unaffected
Genetic Mapping
1. DNA Polymorphisms
  1. RFLPs
  2. SNPs
  3. VNTRs/STRs
Genetic Structure of Populations
1. Population Genetics
  1. applies genetic principles to entire populations of organisms
2. Subpopulation
  1. population unit, a.k.a local population
3. Gene Pool
  1. all alleles in a population
4. Genotype Freq.
  1. proportion of indiv. in population wtih specific genotype
5. Allele Freq.
  1. proportion of each indiv. allele in a population
6. Hardy-Weinberg Principle
  1. p2 + 2pq + q1 =1
Inbreeding
1. combine alleles of common ancestry
2. Leads to genes becoming fixed and loss of variation
3. Commercial use in plants
  1. Heterosis
    1. rapid growth, larger size, bigger crop yield
Forces of Evolutionary Change
1. Mutastion
  1. ultimate source of variation
  2. caused by UV and chemicals
2. Modes of Natural Selection
  1. Stabilizing Selection
    1. intermediate favoured over extreme phenotypes
  2. Directional Selection
    1. change in environ. drives selection towards certain phenotype
  3. Diversifying Selection
    1. creates 2 peaks- 2 outlying phenotypes preferred
  4. Balancing Selection
    1. Heterozygote advantage
  5. Migration
    1. movement of alleles between population
  6. Genetic Drift
    1. can fix genes in population after interbreeding
Selection
1. Evolution
  1. process of change in inherited characters of a population over successive generations
2. Individual Fitness
  1. ability to survive and reproduce
3. Genotype Fitness
  1. mean fitness of all people in the population with genotype
4. Relative Fitness
  1. standardised measure relative to fittest genotype
  2. made up of survival and reproductive components
5. Drivers of Natural Selection
  1. changing environment
  2. random mutation
6. Sexual Selection
  1. selection that favours traits that increase reproductive success
  2. Intra Sexual
    1. competition for mates
  3. Inter Sexual
    1. mate choice
Speciation and Species
1. Micro-evolution
  1. evolution within population/species
2. Macro-evolution
  1. evolution within taxa
3. Speciation
  1. 2 species formed from one and cannot reproduce any more
  2. Allopatric
    1. physical isolation
  3. Peripatric
    1. geographical isolation
4. Mating Mechanisms
  1. Pre
    1. ecological, seasonal, sexual, mechanical
  2. Post
    1. gametic isolation, hybrid viability, hybrid sterility, hybrid breakdown
5. Species
  1. Sibling
    1. 2 species similar in morphology
  2. Sub
    1. distinguishable by more than one character
Phylogeny
1. Cladogenesis
  1. splitting of evolutionary lineages to form clades
    1. Monophyletic
      1. all related
    2. Paraphyletic
      1. ancestor and some descendants related
    3. Polyphyletic
      1. 2 convergent descendants but no common ancestor
2. Anagenesis
  1. change within species over time
3. Terminology
  1. Plesiomorphy
    1. character state found in ancestor of group
  2. Apomorphy
    1. derived character state in descendants
  3. Symplesiomorphy
    1. shared ancestral character state
  4. Synapomorphy
    1. shared derived character state
Altruism
1. An action which increases fitness of another whilst reducing fitness of actor
2. Mechanisms
  1. Group Selection
  2. Kin Selection
  3. Reciprocal Altruism
  4. Status
3. Hamilton's Rule
  1. rb-c > 0
Biodiversity and Conervation
1. Levels
  1. Genetic
  2. Organism
  3. Ecosystem
2. Species-Area Relationship
  1. lower latitude = more diverse
  2. larger areas = more species
3. Threats to biodiversity
  1. Human activity = biggest threat
  2. 6th mass extinctions?

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	Created by glesni.prytherch almost 10 years ago