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Exam 4 - Coggle Diagram

- - - - 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
      - Limited resources
      - Human population size: http://www.worldometers.info/world-population/
      - 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
  - - - 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
- - - - 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 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
    - - predicts an equilibrium-unchanging allele and genotype frequencies from generation to generation-if certain conditions exist 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
      - provides a quantitative relationship 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.
    - - If, instead, we always use p and q rather than choosing an upper and lowercase letter to represent alleles:
      - 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
    - - HW predicted frequencies
        
        Allele
        
        r, q = 0.497,
        
        R, p = 0.50
        
        Genotype
        
        rr, q2 = 0.247,
        
        RR, p2 = 0.2527,
        
        Rr, 2pq = 0.500
      - 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
      - Data for practice
    - - 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
- - - - Each chromosome has a partner
      - 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
        
        Ex: human with 46 chromosomes
        
        246 = 7.04 x 1013
    - - 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
      - Segregation
      - Independent Assortment
    - - 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
    - - Punnett square
      - Visual representation of the offspring inheritance patterns
      - Monohybrid is a cross between 2 homozygous parents with different alleles.
    - - 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
    - - Same as previous video
      - For reference
      - Parental
        
        True breeding
        
        Homozygous
      - F1
        
        First filial generation
        
        Heterozygotes
      - Genotypic ratio
        
        Allele combinations
      - Phenotypic ratio
        
        Trait combinations
  - - - 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
    - - Strawberry
      - Chemically induced
      - Prevent microtubule formation
      - Required for meiosis to occur properly
      - 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