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Exam 4: Heredity, Population Genetics, and Community Ecology - Coggle…

- - - - Each chromosome pairs up
      - Homologous chromosomes
      - Resemble each other in size, shape & 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 2n
    - - 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:
      - Multiple deleterious alleles can be bunched together and eliminated
      - Escape host-parasite negative impacts
      - Pollination
      - Cross pollination vs
      - Self pollination
      - Genetic diversity
      - Bet-hedging to novel environments
  - - - 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
    - - 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
      - Inherit a homologous chromosome
      - During meiosis, 2 members of a gene pair separate from each other
      - Each gamete has an equal chance to inherit either one of the genes
    - - 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 2 alleles
    - - Punnett square
      - Visual representation of the offspring inheritance patterns
      - Monohybrid is a cross between 2 homozygous parents with different alleles.
    - - Incomplete Dominance
        
        Phenotype of heterozygote is intermediate between those of parent homozygotes
        
        Snapdragons
        
        Red x white = pink
      - Multiple Alleles
        
        Many populations have more than 2 alleles for a particular locus
        
        Punnett square theoretical crossing works similar
        
        Breeding experiments to determine dominance
      - Mutations #
        
        Changes in the genetic makeup of an individual
        
        Point mutation
        
        Single nucleotide change
        
        Chromosome mutation
        
        Deletion
        
        Segments of chromosome 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
      - No Crossing Over
        
        Fail to mix alleles across homologs
        
        Chromosome inherited same as parent
        
        Only 2 gamete types possible rather than 4
      - Polygenic Inheritance
        
        Multiple genes for one character
        
        Phenotype is cumulative result of combined effects of many genes
        
        Most traits
        
        Continuous variation
        
        Populations tend to have normal distribution
      - Epistasis
        
        One gene interacts with another
        
        May interfere or mask
        
        Ex: digitalis petal color
      - Linkage
        
        4 haploid genotypes
        
        Not produced in equal numbers
        
        Recombinants less abundant
        
        Parentals more abundant
      - Pleiotropy
        
        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 greater yield than those without awns
      - Polyploidy
        
        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
        
        Evolutionary Significance
        
        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 with unlimited resources, population keeps growing
    - - Population with limited resources, population self-regulates
    - - Overshoot results in die-off due to limited resources
  - - - Grow exponentially
      - Disturbed areas
      - Weedy
      - Annuals
      - Little investment in defense
      - Many, small fruits
    - - 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 at age x
      - lx(Fx)x = average number of offspring per capita at time x, weighted by age x
      - Survivorship Curves/Age Structures
        
        Visual representation of survivorship
        
        Type I, typical of K-selected species
        
        Type III, typical of r-selected species
        
        Dependent on environment
        
        Same species can display all 3
  - - - Beneficial interactions +
      - Negative interaction -
      - Facilitation (+/+)
      - Benefits both
      - Mutualism
      - Pollination
      - Commensalism (0/+)
      - Benefits one, neutral to the other
      - Amensalism (0/-)
      - Negative to one & neutral to other
      - Competition (-/-)
      - Both are negatively impacted
      - Competition for resources
      - Predation (+/-)
      - Herbivory
      - Parasitism
      - Predator-Prey Cycle Modeling #
        
        At low prey and predator population sizes, prey increase exponentially
        
        As more food for predators is available, predator survival and reproductive success increases, resulting in predator population growth following that of their prey
        
        As predator populations increase, prey death rate exceeds birth rate, resulting in prey decline
        
        As prey number declines, there is not enough food to sustain a high predator population and thus predator death rate exceeds that of birth rate
        
        Lotka-Volterra Models
        
        dN/dt = rN-aNP
        
        dN/dt=rate of change with time of the prey population
        
        r=intrinsic rate of increase for prey
        
        N=number of prey individuals
        
        a=predator’s per capita attack rate
        
        Number of prey eaten per predator per unit time
        
        P= number of predator individuals
        
        dP/dt = faNP-qP
        
        dP/dt= rate of change with time of predator population
        
        f=constant, indicating predator’s efficiency at converting the prey it has eaten into new predators
        
        q=predator’s per capita mortality rate
- - - - 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 Frequencies
        
        Allele frequency
        
        Number of copies of an allele in a population
        
        Divided by
        
        The total number of all alleles for that gene in a population
        
        Allele relative frequencies:
        
        Frequency of R: # copies of allele R
        
        Total number of alleles (R & r)
        
        Number of copies of an allele in a population divided by the total number of 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 all individuals in a population
        
        Number of individuals with a particular genotype in a population divided by the total number of individuals in a population
    - - No new mutations
        
        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
        
        Polymorphism
        
        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
      - No genetic drift. The population is so large allele frequencies do not change due to random sampling effects
        
        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
      - No migration
        
        Movement of alleles into and out of a population
        
        Immigration
        
        Into
        
        Emigration
        
        Out of
        
        Can be impeded by
        
        The environment
        
        Life history
        
        Repercussions for
        
        GMO and
        
        climate change
        
        speciation
      - No natural selection #
        
        One allele selectively advantageous
        
        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 population size
        
        Artificial Selection
        
        Selection by humans
        
        Increased frequency of desired trait
        
        Elimination of undesired traits
        
        Crop breeders for thousands of years
      - Random mating #
        
        Plants “choose” their mates
        
        Male-male competition
        
        Excess of pollen grains
        
        Pollen tubes can interfere with one another
        
        Female choice
        
        Barriers on stigma surface preventing germination
        
        Pollinator vectors
        
        Pollination syndromes
        
        Some of the individuals reproduce more than others
        
        Based on individual phenotypes
    - - p2+2pq+q2=1
      - p2= genotypic frequency of RR
      - 2pq= genotypic frequency of Rr
      - q2= genotypic frequency of rr