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