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Test four - Coggle Diagram

- - - - each chromosome has a parnter
      - homologous chromosomes
      - resemble each other in size, shape, and hereditary information
      - each homolog is from a different parent
      - interactions of genes on each sets of chromosomes determines the genetic characteristics
    - - During Metaphase I
        
        Orientation of bivalents is random
      - During Metaphase II
        
        Orientation of sister chromatids is random
      - in general the possibilities are 2^n
        
        Ex: human with 46 chromosomes
        
        2^46= 7.04 x 10^13
    - - During Prophase I
      - Synaptonemal complex forms
      - mixes the genes present in homologous chromosomes
      - results in new combinations not present in the chromosomes of the parental cells
      - usually at least one chiasma occurs between every pair of homologous chromosomes
    - - New combination of alleles from each parent
      - Promotes heterozygosity
      - Advantages include
        
        genetic diversity
        
        bet-hedging to novel environments
        
        multiple deleterious alleles can be bunched together and eliminated
        
        escape host-parasite negative impacts
      - pollination
        
        cross pollination vs self pollination
  - - - Dominance
        
        principle of dominance
        
        Each individual has a unique genotype
        
        genotype is made up of alleles
        
        phenotypes determined by these alleles (and the environment)
        
        There is no guarantee that an allele will manifest
        
        heterozygosity
        
        one of 2 genes (dominant allele) has a detectable effect on an organism's appearance
        
        The other gene has no discernable effect (recessive allele)
        
        homozygosity
        
        both alleles are the same
      - Segregation
        
        principle of segregation
        
        alleles are segregated, separated, from one another during meiosis
        
        each gamete contains only one allele for each gene
        
        offspring inherit 2 alleles for a gene one from each parent
        
        one from each parent
        
        inherit a homologous chromosome
        
        during meiosis, 2 members of a gene pair separate from each other
        
        Each gamete had an equal chance to inherit either one of the genes
      - Independent assortment
        
        Principle of independent assortment
        
        gene pairs that are not related (homologs) segregate independently
        
        gene pairs that are not linked segregate independently
        
        evidence provided from a dihybrid cross
        
        3:1 phenotypic ratio for each of the two alleles
        
        Dihybrid example
        
        parental
        
        true breeding
        
        homozygous
        
        F1
        
        first filial generation
        
        heterozygous
        
        genotypic ratio
        
        allele combinations
        
        phenotypic ratio
        
        trait combinations
    - - Punnett square
      - visual representation of the offspring inheritance patterns
      - monohybrid cross is a cross between 2 homozygous parents with different alleles
  - - - phenotype of heterozygote is intermediate between those of parent homozygotes
      - snapdragons
        
        red x white = pink
    - - many populations have more than 2 alleles for a particular locus
      - Punnett square theoretical crossing works similar
      - breeding experiments to determine dominance
      - figuring out alleles is complex
    - - Changes in the genetic makeup of an individual
      - point mutation
        
        single nucleotide change
      - chromosome mutation
        
        deletion
        
        segments of chromosomes are lost
        
        duplication
        
        part of the chromosome has doubled
        
        inversion
        
        piece rotates 180
        
        translocation
        
        exchange of parts between 2 nonhomologous chromosomes
        
        transposons
        
        movable genetic element
        
        jumping genes
    - - Fail to mix alleles across homologs
      - chromosome inherited same as parent
      - only 2 gamete types possible rather than 4
    - - multiple genes for one character
      - phenotype is cumulative result of combined effects of many genes
      - example abscisic acid
      - most traits
      - continuous variation
      - populations tend to have normal distribution
    - - one gene interacts with another
      - may interfere or mask
      - Ex: digitalis petal color
        
        one gene impacts red intensity
        
        d light red
        
        D dark red
        
        pigment location
        
        w throughout corolla
        
        W spots of nectar guide
    - - 4 haploid genotypes
      - not produced in equal numbers
        
        recombinants less abundant
        
        parentals more abundant
    - - single gene with multiple effects on the phenotype
      - inheritance of a single gene which visibly influences several traits
      - Ex: awn of wheat
        
        Wheat with awns have a greater yield than those without awns
    - - selfer
        
        small petals
        
        flower early
        
        seasonal drought
        
        physiologically escape
      - outcrosser
        
        large petals
        
        flower late
        
        seasonal drought
        
        physiologically tolerant
    - - having more than two copies (2n) of a chromosome
      - autopolyploid
        
        failed meiosis
        
        self fertilization
      - allopolyploid
        
        meiotic error
        
        mismatch during mating
        
        second mating creates matched pairs
      - polyploid example
        
        wheat
        
        result if sequential hybrid doubling and quadrupling
        
        original ancestral species had 14 chromosome
        
        Durum wheat
        
        28 chromosomes
        
        tetraploid
        
        pasta
        
        Bread wheat
        
        42 chromosome
        
        hexaploid
        
        gluten for lofty bread
        
        strawberry
        
        chemically induced
        
        prevent microtubule formation
        
        produce diploid gametes
        
        During fertilization 2 diploid gametes fuse
        
        results in tetraploid (4n)
    - - polyploid mask deleterious recessive alleles
      - Relax selection pressure
        
        accumulate mutations that eventually result in beneficial trait
      - 2 groups of ancient duplications
        
        common ancestor of seed plants
        
        common ancestor of extant angiosperms
- - - - population size (N)
      - Exponential growth
        
        J-shaped curve
        
        unlimited resources
      - logistic growth
        
        S-shaped curve
        
        typical of a population that
        
        self regulates
        
        has a carrying capacity (K)
        
        reaching carrying capacity
        
        overshoot K
        
        result in die off
        
        limited resources
      - growth models
        
        r = intrinsic growth rate
        
        N= population size
        
        K= carrying capacity
        
        dN/dt =population change over time
        
        exponential growth
        
        dN over dt equals r times N
        
        dN/dt=rN
        
        Logistic growth
        
        dN over dt equals r times N times the quantity one minus N divided by K
        
        dN/dt=rN[(K-N)/K]
        
        rN(1-N/K)
        
        r- vs K- selected species
        
        r-selection
        
        grow exponentially
        
        disturbed areas
        
        weedy
        
        annuals
        
        Little investment in defense
        
        many, small fruits
        
        K-selected
        
        fluctuate around carrying capacity
        
        fairly stable habitats
        
        perennials
        
        invest in defenses
        
        resource - intensive fruits
  - - - stress
        
        resource availability
        
        water
        
        nutrients
        
        light
        
        growth inhibitors
        
        temperature
        
        toxins
      - disturbance
        
        biotic
        
        herbivory
        
        pathogens
        
        anthropogenic
        
        abiotic
        
        fire
        
        wind
      - 3 life stages
        
        C- competitors
        
        S- stress tolerators
        
        R- ruderals
  - - - x=age
      - Nx= number of individuals alive at age x
      - Sx= proportion of individuals of age x that survive to age x+1
        
        Nx+1/Nx
      - Lx=proportion of individuals that survive from birth (age 0) to age x
        
        Nx/N0
      - Fx=average number of offspring born to a female while she is age x
      - Lx(Fx)= average number of offspring per capita age x
      - Lx(Fx)X= average number of offspring per capita at time X weighted by age x
      - R0
        
        calculated by the sum of the offspring or individual column
        
        represents the expected number of offspring an individual will produce over its lifetime in the population
        
        if R0>1 population increases
        
        If R0<1 the population size decreases
        
        If R0=1 population does not change
- - - - all of the alleles of every gene in a population make up the gene pool
      - a population is a group of individuals of the same species that occupy the same region and can interbreed with each other
      - Allele and genotype relative frequencies
        
        allele frequency
        
        number copies of an allele in a population divided by the total number of alleles for that gene in a population
        
        allele relative frequency
        
        number of copies of an allele in a population
        
        divided by
        
        the total number of all alleles for that gene in a population
        
        genotype frequency
        
        number of individuals with a particular genotype in a population divided by the total number of individuals on a population
        
        number of individuals with a particular genotype in a population
        
        divided by
        
        the total number of all individuals in a population
    - - No New mutations
      - no genetic drift. The population is so large allele frequencies do not change due to random sampling affects
        
        No Migration
        
        No natural selection
        
        random mating
      - Provides a quantitative relationships between the allele and genotype frequencies
    - - consider a dimorphic population (2 alleles) such as our red and white flowers with alleles R & r
      - all alleles in the population add up to 100% or 1
      - all genotypes in the population add up to 100% or 1
      - Red & White flower examples
        
        allele frequencies
        
        r=0.38
        
        R=0.62
        
        0.38+0.62=1
        
        genotypic frequencies
        
        rr= 0.25 RR= 0.48 Rr= 0.27
        
        0.25+0.48+0.27=1
    - - genotypic frequency
        
        RR=0.38
        
        Rr= 0.24+0.24= 0.48
        
        rr=0.14
      - the frequency of gametes carrying a particular allele is equal to the allele frequency for a population in Hardy-Weinberg equilibrium
      - multiplying the allele frequencies gives the proportion of each allele combination in the population
    - - p^2= genotypic frequency of RR
      - 2pq=genotypic frequency of Rr
      - q^2=genotypic frequency of rr
    - - microevolution
        
        changes in a population's gene pool from generation to generation
        
        factors
        
        no mutation
        
        mutation
        
        change in one of the nucleic acids
        
        some are apparent in phenotype
        
        source of all new alleles
        
        must be in gametes to be inherited
        
        male pollen sperm
        
        female ovule egg
        
        no natural selection
        
        natural selection
        
        one allele selectively advantagous
        
        In this example, 2 (triangle) has more vigorous offspring
        
        over time individuals with the 2 genotype are able to reproduce more and grow in numbers
        
        the overall vigor of the population grows
        
        so does the population size
        
        artificial selection
        
        selection by humans
        
        2 more items...
        
        crop breeders for thousands of years
        
        Example Brassica
        
        genetic drift
        
        random loss of alleles
        
        acts most strongly in small populations relative to large
        
        bottleneck effect
        
        large population diminished suddenly
        
        natural catastrophe
        
        migration
        
        may increase in size again but unlikely to regain original diversity
        
        adaptive radiation
        
        bottleneck from long distance dispersal
        
        followed by adaptive radiation
        
        Example: Hawaiian lobeliads
        
        migration
        
        gene flow
        
        movement of alleles into and out of a population
        
        immigration
        
        1 more item...
        
        emigration
        
        1 more item...
        
        can be impeded by
        
        the environment
        
        life history
        
        repercussions for
        
        GMO
        
        climate change
        
        speciation
        
        nonrandom mating
        
        plants "choose" their mates
        
        pollinator vectors
        
        pollination syndromes
        
        some individuals reproduce more than others
        
        based on individual phenotypes
        
        sexual selection
        
        Male-male competition
        
        excess pollen grains
        
        pollen tubes can interfere with one another
        
        female choice
        
        barriers on stigma surface preventing germination
    - - dimorphic
        
        2 phenotypes
        
        Dominant-recessive systems
      - polymorph= many phenotypes in a population
      - Example:Aquilegia
      - color variation
      - spur-length variation
      - can be due to a single nucleotide polymorphism
  - - - death does not mean natural selection has occurred
      - differential survival
      - survival due to phenotypes that are heritable
        
        phenotype coded by genotype
      - Natural selection related to molecular genetics
        
        within a population there is allelic variation arising from various factors such as mutations causing differences in DNA sequences
        
        Distinct alleles may encode proteins of differing functions
        
        some alleles may encode proteins that enhance an individual's survival or reproductive capacity
        
        individuals with beneficial alleles are more likely to survive and reproduce
        
        over the course of many generations allele frequencies of many different genes may change through natural selection
        
        this significantly alters the characteristics of a species
        
        the net result of natural selection is a population that is better adapted to its environment and/or more successful at reproduction