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Exploring botanical heredity, population dynamics, and community ecology -…

- - - - each chromosome has partner
      - homologous pairs
      - each homolog from different parent
      - genetic interaction determines characteristics
    - - different genes assort independently because they are located on different chromosomes
      - random alignment of different chromosomes at metaphase plate during meiosis I
    - - happens during prophase I
      - mixes genes present in homologous
      - results in new combinations not present in chromosomes of parental cells
    - - new combination of alleles from each parent
      - promotes heterozygosity
      - Advantages:
        
        genetic diversity
      - pollination
        
        cross pollination vs self-pollination
  - - - each individual has unique genotype
      - genotype made up of alleles
      - phenotypes determined by these alleles and environment
      - no guarantee an allele will manifest
    - - alleles are segregated (separated) from one another during meiosis
      - each gamete contains only one allele for each gene
      - during meiosis 2 members of a gene pair seperate from each other. each gamete equal chance to inherit either one of the genes
    - - gene pairs that are not related (homologs) segregate independently
    - - punnett square
  - - - phenotype of heterozygote is intermediate between those of homozygous parents
      - Example
        
        Snapdragons... red x white = pink
    - - many populations have more than 2 alleles for particular locus
      - punnett square theoretical crossing works similar
    - - changes in genetic makeup of an individual
      - point mutation
        
        single nucleotide change
      - chromosome mutation
        
        deletion
        
        segments of chromosome lost
        
        duplication
        
        part of chromosome doubled
        
        inversion = piece rotates 180
        
        translocation
        
        exchange of parts between 2 non homologous chromosomes
        
        transposons
        
        jumping genes
    - - fail to mix alleles across homologs
      - chromosome inherited same as parent
      - only 2 gamete types possible rather than 4
    - - one gene interacts with another
      - may interfere or mask
      - Examples
    - - 4 haploid genotypes
      - not produced in equal numbers
        
        recombinants less abundant
        
        parentals more abundant
    - - single gene with multiple effects on phenotype
      - inheritance of a single gene which visibly influences several traits
    - - having more than two copies (2n) of a chromosome
      - autopolyploid
        
        failed meiosis
        
        self fertilizagtion
      - allopolyploid
        
        meiotic error
        
        mismatch during mating
        
        second mating creates matched pairs
      - Examples
- - - - all of the alleles of every gene in a populaiton make up the gene pool
      - population = group of individuals of same species that occupy same region and can interbreed w/ each other
      - Allele & genotype relative frequencies
        
        allele frequency
        
        number of copies of an allele in a population divided by total number of alleles for that gene in a population
        
        genotype frequency
        
        number of individuals w/ a particular genotype in a population divided by total number of individuals in a population
  - - - changes in a population's gene pool from generation to generation
      - factors
        
        mutation, natural selection, genetic drift, migration, nonrandom mating
    - - change in one of the nucleic acids
      - some apparent in phenotype
      - source of all new alleles
      - must be in gametes to be heritable
        
        male pollen sperm
        
        female ovule egg
    - - dimorphic
        
        2 phenotypes
      - polymorph = many phenotypes in population
    - - random loss of alleles
      - acts most strongly in small populations relative to large
      - bottleneck effect
    - - plants "choose" mates
      - pollinator vectors
        
        pollination syndromes
      - some individuals reproduce more than others
      - Sexual selection
        
        male-male competition
        
        excess pollen grains, pollen tubes can interfere with one another
        
        female choice
        
        barriers on stigma surface preventing germination
    - - movement of alleles into and out of a population
      - immigration = into
      - emigration = out of
      - can be impeded by environment, life history
      - repercussions for: GMO and climate change, speciation
    - - bottleneck from long distance dispersal
    - - one allele selectively advantageous
    - - selection by humans
        
        increased frequency of desired trait
        
        elimination of undesired traits
      - crop breeders for thousands of years
  - - - death does not mean natural selection has occurred
      - differential survival
      - survival due to heritable phenotypes
        
        phenotype coded by genotype
- - - - population size (N)
      - exponential growth
        
        J curve
        
        no limitations
      - logistic growth
        
        s curve
        
        carrying capacity
    - - overshoot K
        
        results in die off
        
        (limited resources)
      - Human population (WOW)
    - - Exponential growth model
        
        dN/dt = rN
      - Logistic growth
        
        dN/dt = rN(1-N/K)
    - - r-selected
        
        grow exponentially
        
        little investment into defenses
        
        many small fruits
      - K-selected
        
        fluctuate around carrying capacity
        
        fairly stable habitats
        
        perennials
        
        invest into defenses
  - - - how long did individuals survivie
      - visual representation of survivorship
      - Type I, Type II, and Type III
        
        Type I example
        
        Poa annua
  - - - bound together by shared environment and network of influence
      - factors affecting interactions: abiotic environment, biotic interactions between species
    - - facilitation, commensalism, amensalism, competition, predation
      - Predator-prey interactions
        
        predator (denoted P)- negative imact on prey, positively impacted by prey
        
        Prey (denoted N)- positive impact on predator, negatively impacted by predator
        
        population sizes are directly influenced by each other
        
        predator-prey cycling
        
        Lotka-Volterra models