Populations
Demography
Hardy-Weinberg equilibrium
Species Interaction
Communities
age distribution
Table parts
Growth
Assumptions/conditions of HW
Patterns of natural selection
Stabilizing selection
Genetic variation #
Mandellian Genetics
Mendel's principles extended
Incomplete dominance
Types of growth 
Exponential (R species)
Logistic (K species)
j-shaped curve, unlimited resources
s-shaped curve, self regulates, has carrying capacity (K)
If species reach K they will start to die off due to limited resources
Growth Models
Formula parts
r=intrinsic growth rate, N=Population size, K=carrying capacity, dN/dt= population change over time,
Formula
Formula
dN/dt = r (N) #
dN /dt =( r )(N) (1-N/K)
#
Traits
Traits
Annuals
perennials
weedy
Disturbed areas
Little investment in defense
many small fruits
Invest in defense
Fairly stable habitat
resource-intensive fruits
Fluctuates around K
early maturity
late maturity
plant strategies
grimes model 
Stress
Disturbance
Resource availability
biotic
Growth inhibitors
nutrient
light
water
toxins
temperature
abiotic
Herbivory
fire
pathogens
anthropogenic (pollution)
wind
3 life-stages
S - Stress tolerators
R - Ruderals
C - Competitors
x=age, Nx=number of individuals alive at age x, Sx=proportion of individuals of age x that that survive to age x+1, Ix=proportion of individuals that survive from birth (0) to age x, Fx= average number of offspring born to a female while she is age x, IxFx= average number of offspring per capita at age x, Ix(Fx)(x)= average number of offspring per capita at time x, weighted by age x
Ro
Ro=individual fecundity, Represents the expected number of offspring an individual will produce over its lifetime in the population.
How to calculate = (survivorship column)(fecundity) or (Lx)(Fx)
if R0=1, then population size does not change
If R0>1, the population size increases.
G
If R0<1, the population size decreases
G=mean generation time, Represents average time between two consecutive generations in the lineage of a cohort
(The average age between parent and offspring)
Calculate by taking the sum of the Age-weighted fecundity column and then dividing by the net reproductive rate
r
r=Intrinsic growth rate
Calculated by taking the natural log of the net reproductive rate divided by the mean generation time.
(Natural log of Ro)/G
If r>0, the population size increases.
If r<0, the population size decreases
if r=1, then population size does not change.
Survivorship curve 
Visual representation of survivorship (how long did individuals survive)
Types
Type2
Type3 #
Type1 #
Most individuals survive until old age
Individuals have a constant chance of dying throughout their lives
Most individuals die young
typical of K-selected species
typical of r-selected species
Some species can display all three, dependent on environment
Plotted logarithmically
Take survivorship (lx) and multiply by 1000, take the log 10 of this value and plot it against age to produce your figure
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
biotic interactions that occur between species
Abiotic enviroment
Range of interactions (+=beneficial, -=negative)
Commensalism (0,+)
amensalism (0,-)
Facilitation(+,+)
Competition (-,-)
predation (+,-)
Benefits both; mutualism; pollination
Benefits one, neutral to other
Negative to one, neutral to other
both are negatively impacted, competition for resources
Herbivory, parasitism
Predator vs prey interaction
Predator = P
Prey = N
-impact on prey, + impacted by prey
+impact on predator, - impacted by predator
Both influence population size
Cycling
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
Gene pool
All of the alleles of every gene in a population make up the gene pool
Relative Frequency
Allele
genotype
Number of copies of an allele in a population divided by the total number of alleles for that gene in a population
Number of individuals with a particular genotype in a population divided by the total number of individuals in a population (population should be half the allele amount since each person has 2)
- 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
Frequencies in populations should add up to 1
Mean = x
HW vs Punnett
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.
click to edit
HW equations
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
p+q=1
(p+q)^2=1^2
p^2+2pq+q^2=1
p^2= genotypic frequency of RR
2pq= genotypic frequency of Rr
q^2= genotypic frequency of rr
Directional selection
Disruptive selection
occurs when individuals with traits on one side of the mean in their population survive better or reproduce more than those on the other.
occurs when the population stabilizes on a particular trait value and genetic diversity decreases.
occurs when individuals of intermediate phenotype are less fit than those of both higher and lower phenotype, such that extremes are favored.
mode of negative natural selection in which an extreme phenotype is favored over other phenotypes, causing the allele frequency to shift over time in the direction of that phenotype.
population mean stabilizes on a particular non-extreme trait value; pushes population towards average trait
extreme values for a trait are favored over intermediate values. In this case, the variance of the trait increases and the population is divided into two distinct groups
x0≠x1
var0=var1
x0=x1
var0>var1
x0=x1
var0<var1
Diploid individual
Trait
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
Each chromosome has a partner
Undergoes
Meiosis (produces sperm or egg from gametes)
Phases
Metaphase II
Prophase I
Metaphase I
Orientation of bivalents is random
Orientation of sister chromatids is random
In general, the possibilities are 2n
Ex: human with 46 chromosomes
2^46 = 7.04 x 1013
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
Sexual reproduction
results in
New combination of alleles from each parent
Promotes heterozygosity
Advantages
genetic diversity
Bet-hedging to novel environments
Multiple deleterious alleles can be bunched together and eliminated
Escape host-parasite negative impacts
3 principles
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
Types of dominance
Heterozygosity (Aa)
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 (AA)(aa)
both alleles are the same
Alleles are segregated, separated, from one another during meiosis
Each gamete (egg or sperm) contains only one allele for each gene
Offspring inherit 2 alleles for a gene
offspring inherit One from each parent
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
Phenotype of heterozygote is intermediate between those of parent homozygotes EX: RedxWhite=Pink
multiple alleles
Many populations have more than 2 alleles for a particular locus
Breeding experiments to determine dominance
Figuring out alleles is complex
Mutations
Changes in the genetic makeup of an individual
Types
point mutation
chromosome mutation
Single nucleotide change
Deletion
Duplication
Inversion
Translocation
Transposons
segments of chromosome lost
Part of the chromosome has doubled
pieces rotate 180
Exchange of parts between 2 nonhomologous chromosomes
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 (most traits are this kind)
Multiple genes for one character
Phenotype is cumulative result of combined effects of many genes
Populations tend to have normal distribution and continuous variation
Epistasis
One gene interacts with another (may interfere or mask)
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
polyploidy
Having more than two copies (2n) of a chromosome
2 types
allo
auto
Failed meiosis
Self fertilization
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