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Exam 5 - Coggle Diagram

- - - - Gene pool
        
        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
    - - 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
    - - 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
    - - Genotypic frequency:
      - 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
  - - - Factors
        
        Mutation
        
        Natural selection
        
        Genetic drift
        
        Migration
        
        Nonrandom mating
      - Changes in a population’s gene pool from generation to generation
    - - Change in one of the nucleic acids
      - Some are apparent in phenotype
      - Source of all new alleles
      - Must be in gametes to be inherited
    - - Polymorph = many phenotypes in a population
      - Example: Aquilegia
      - Color variation
      - Spur-length variation
      - Can be due to a single nucleotide polymorphism
      - Dimorphic
    - - Random loss of alleles
      - Acts most strongly in small populations relative to large
      - Bottleneck effect
    - - Plants “choose” their mates
      - Pollinator vectors
      - Some of the individuals reproduce more than others
    - - Male-male competition
        
        Excess of pollen grains
        
        Pollen tubes can interfere with one another
      - Female choice
        
        Barriers on stigma surface preventing germination
    - - 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
  - - - Death does not mean natural selection has occurred
      - Differential survival
      - Survival due to phenotypes that are heritable
    - - 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
- - - - Population size (N)
      - Exponential growth
      - Logistic growth
    - - r = intrinsic growth rate
      - N = population size
      - K = carrying capacity
      - dN/dt = population change over time
      - Exponential growth
      - Logistic growth
    - - 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
  - - - 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
    - - 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
    - - 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