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Botany Exam 4, Mendelian genetics, Genetic Variation OIP (1) - Coggle…

- - - - To predict if a population will grow or shrink, ecologists need to know birth and death rates for organisms at different ages as well as the current age and sex makeup of the population.
      - Life tables summarize birth and death rates for organisms at different stages of their lives.
      - Population age structure—Are there lots of: young individuals? Old individuals? Reproductive age individuals?; and similar questions
      - Population growth rate—How fast is the population size growing (or shrinking)? Population survivorship patterns—Does most mortality occur in the very young? The very old? Or equally across all ages?
    - - 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
    - - Calculate the net reproductive rate (R0)
      - Calculated by taking the sum of the offspring/individual column.
      - Represents the expected number of offspring an individual will produce over its lifetime in the population.
        
        If R0>1, the population size increases.
        
        If R0<1, the population size decreases, and
        
        if R0=1, then population size does not change.
    - - Calculate the mean generation time (G)
      - Calculated by taking the sum of the Age-weighted fecundity column and then dividing by the net reproductive rate
      - Represents average time between two consecutive generations in the lineage of a cohort
      - The average age between parent and offspring
      - For humans, typically 20-35 years of age
    - - Calculate the intrinsic growth rate (r)
      - Calculated by taking the natural log of the net reproductive rate divided by the mean generation time.
        
        If r>0, the population size increases.
        
        If r<0, the population size decreases, and
        
        if r=1, then population size does not change.
    - - How long did individuals survive
      - 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
    - - Survivorship curves are plotted logarithmically
      - Take survivorship (lx) and multiply by 1000
      - Take the log10 of this value
      - Plot against age to produce a figure
      - Example: Type I curve
  - - - a group of actually or potentially interacting species living in the same location.
      - bound together by a shared environment and a network of influence each species has on the other.
      - factors affecting interactions include
      - abiotic environment
      - biotic interactions that occur between species
    - - Range of interactions
      - 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
      - P
      - Negative impact on prey
      - Positively impacted by prey
      - Prey
      - N
      - Positive impact on predator
      - Negatively impacted by predator
      - Population sizes are influenced by each other
    - - r = intrinsic growth rate
      - N = population size
      - K = carrying capacity
      - dN/dt = population change over time
      - Exponential growth
      - Logistic growth
      - Can similar model predator-prey growth and the impact each has on the other
    - - 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
    - - 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
    - - Prey population change
      - The number of prey N = 1200,
      - rate of capture or the predation constant a = 0.004,
      - Intrinsic growth rate, r = 0.7 = and
      - Number of predators, P = 130?
      - dN/dt = rN-aNP
      - Predator population change
      - N = 1200,
      - a = 0.004,
      - f = 0.025 predator birth constant,
      - q = 0.12 predator death constant
      - and P = 130 number of predators
      - dP/dt = faNP-qP
  - - - 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)
    - - Overshoot K
      - Result in die off
      - Population size:
        
        01April2019 10am: 7,694,293,260
      - 31March2020 6:46am: 7,774,589,054
      - 04Nov2020 7:46am: 7,849,224,195
      - 16April2022 2:04pm: 7,940,768,458
    - - r = intrinsic growth rate
      - Relevant for r > 0
      - N = population size
      - K = carrying capacity
      - dN/dt = population change over time
      - Exponential growth
      - dN over dt equals r times N
      - Logistic growth
      - dN over dt equals r times N times the quantity one minus N divided by K
    - - Exponential growth
      - dN/dt = rN
      - Logistic growth
      - dN/dt = rN[(K-N)/K] =
      - rN(1-N/K)
    - - r-selected
      - 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
    - - Plants must make trade-offs due to environmental necessities
      - Many strategies exist
      - Grime’s model
      - 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
- - - - A population is a group of individuals of the same species that occupy the same region and can interbreed with each other
      - All of the alleles of every gene in a population make up the gene pool
    - - Allele frequency
      - 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 individuals in a population
    - - Number of copies of an allele in a population
      - Divided by
      - The total number of all alleles for that gene in 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 effects
      - No migration
      - No natural selection
      - Random mating
    - - Consider the following phenotypes & genotypes
      - 45 red flowered, homozygous plants
      - 25 red flowered, heterozygous plants
      - 23 white flowered plants
      - 45 RR
      - 25 Rr
      - 23 rr
    - - Freq of individuals with rr genotype:
      - individuals homozygous recessive
      - total # of individuals within population
      - Freq of individual with RR genotype
      - individuals homozygous dominant
      - total # of individuals within population
      - Freq of individuals with Rr genotype
      - individuals that are heterozygous
      - total # of individuals within population
    - - 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.
    - - The frequency of the dominant allele is represented by p
      - The frequency of the recessive allele is represented by q
      - Thus p+q=1
      - Therefore (p+q)2=12;
      - And p2+2pq+q2=1
      - p2= genotypic frequency of RR
      - 2pq= genotypic frequency of Rr
      - q2= genotypic frequency of rr
    - - Actual frequencies
      - Allele
      - r = 0.38,
      - R = 0.62
      - Genotype
      - rr = 0.25,
      - RR = 0.48,
      - Rr = 0.27
  - - - 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 are apparent in phenotype
      - Source of all new alleles
      - Must be in gametes to be inherited
      - Male pollen sperm
      - Female ovule egg
    - - 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
    - - 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
    - - Plants “choose” their mates
      - Pollinator vectors
      - Pollination syndromes
      - Some of the individuals reproduce more than others
      - Based on individual phenotypes
    - - Male-male competition
      - Excess of 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
      - The environment
      - Life history
      - Repercussions for
      - GMO and
      - climate change
      - speciation
    - - Bottleneck from long distance dispersal
      - Followed by adaptive radiation
      - Example: Hawaiian lobeliads
    - - 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
    - - Selection by humans
      - Increased frequency of desired trait
      - Elimination of undesired traits
      - Crop breeders for thousands of years
      - Example Brassica
  - - - Review how to make a frequency histogram
      - Steps summarized
      - Find your Min & Max values
      - Determine the number of bins
      - Count the number of observations for each bin
      - Draw bars for each bin with the frequency
    - - Death does not mean natural selection has occurred
      - Differential survival
      - Survival due to phenotypes that are heritable
      - Phenotype coded by genotype
    - - 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
- - - - 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 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
    - - 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 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
    - - Wheat
      - Result of sequential hybrid doubling and quadrupling
      - Original ancestral species had 14 chromosomes
      - Durum wheat
      - 28 chromosome
      - Tetraploid
      - pasta
      - Bread wheat
      - 42 chromosome
      - Hexaploid
      - Gluten for lofty bread
    - - 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