Studied by 2 peoplewhat factors influences population growth?
for population size, what does it mean when r > 0?
population is increasing over time
for population size, what does it mean when r = 0?
population remains the same
for population size, what does it mean when r < 0?
population is decreasing
what is one method for estimating population size?
mark/recapture
what happens in mark/recapture?
mark: capture some individuals and visually tag or mark them
recapture: release the ind. into the wild, wait long enough for them to evenly spread through the population, and then, recapture a second set of ind. to see how many are marked.
R/C = M/N, where:
N = total pop. size
M = the # of caught, marked, and released (1st sampling)
C = # caught in second sampling
R = the # of marked ind. recaptured in 2nd sampling
the ratio of tagged ind. in our second sampling should equal # of tagged ind. in FULL population
can population size increase exponentially forever? why or why not?
no because at some point, some kind of factor will limit size of popuation
density independent controls
factors (usually abiotic) affecting pop. size that DO NOT depend on the # of organisms in the population
factors affect pop. in the same way, regardless of how many ind. there are
density dependent controls
factors (usually biotic) affecting pop. size that DO depend on the number of organisms in the population
has a stronger impact on pop., when there are more individuals in pop.
alcohol is produced as a byproduct of fermentation of sugar by yeast. the maximum ABV% that a solution can achieve is ~15% because yeast cannot survive in higher concentrations of waste products. this is an example of…
a. density dependent control
b. density independent control
a. density dependent control
this is because more individuals → more waste
wildfire is an example of…
a. density independent control
b. density dependent control
b. density dependent control
this is because we are talking about the species that are the fuel. the answer would be ‘a’ if we are referencing the species that are not the fuel.
when N_0 is large, (K - N_0) = 0 (approx.), (K - N_0)/K = 0 (approx) and…
growth is slow
when N_0 is small, (K - N_0) = K (approx.), (K - N_0)/K = 1 (approx) and…
growth is mostly exponential
survivorship
the proportion of individuals surviving from birth to age class x, represented by l_x
fecundity
the avg. # of offspring an individual will produce during age class x, represented by m_x
tells us how much reproduction is occurring per individual
not how many babies were produced per individual
R_0
the net reproductive rate; the mean # of offspring produced per individual across their lifetime
represented by Σlxmx (a.k.a. survivorship x fecundity)
G
generation time; average age of parents across all offspring produced
average age of production
G = xl_xm_x (for ind.)
what is r in terms of R_0 and G?
r is approx. [ln(R_0)]/G
R_0 and r are (positively/negatively/not) related
positively
if R_0 = 1
the population is not changing
each ind. only has ONE offspring, replacing itself in next gen.
higher survivorship at large juvenile stages leads to
higher reprodctive power later on
r is correlated with the number of individuals at the
reproductive age
if there is a large proportion of ind. at reproductive ages,
large r
how could the fossil record provide evidence for gradualism?
gradual difference in the fossils over time
descent with modification produces
homologous traits
homologous traits
traits that are similar in different organisms because they were inherited from common ancestor
convergent evolution produces
analogous traits
analogous traits
traits similar in different organisms because of similar selective pressure
arew wings analogous or homologous?
analagous
common ancestor of all mammals did not have wings as not every mammal has wings
which of the following evolves (in scienctific terms)?
a. some populations
b. all populations
b. all populations - evolving at all times
evolution
genetic change over time
adaptation
a type of evolution that occurs through natural selection
microevolution (within ____)
species; changes in genetic variants over generations
macroevolution
speciation; btwn. species; accumulation of many microevolutionary changes, such that new groups arise
4 conditions for natural selection
reproduction, variation, inheritance, success
what kind of selection is this?
stabilizing selection
Stabilizing selection
Phenotypes nearest the mean have the highest fitness. The mean stays the same and variation is reduced.
what kind of selection is shown below?
Directional selection
Directional selection
Phenotypes at one extreme have the highest fitness, and the mean trends toward that extreme.
What kind of selection is shown below?
Disruptive (diversifying) selection
Disruptive (diversifying) selection
Phenotypes at both extremes have higher fitness than the mean. variation is increased, and bimodal pattern emerges
intermediate have lowest fitness
Balancing selection is also known as
Frequency dependent selection
Balancing selection maintains
variation in a population
Frequency-dependent selection
Rarer phenotypes have the highest fitness. frequency of a given phenotype oscillates.
will always see oscillation over time
variation is maintained
Sexual selection is selection driven by
Competition for mates
mate choice
Altruism
A behaviour that reduces individual fitness and increases the fitness of other individuals
Kin selection
Favors behaviors that increase the reproductive success of relatives
Inclusive fitness
The sum of an individual's own fitness, and its contribution to the duchess success/survival of relatives
hamilton’s rule
rB = C, where:
r = coefficient of relatedness: the fraction of genes shared between relatives
B = benefit to relative: the increase in offspring for the relative
C = cost to the altruist: the loss in offspring for the altruist
reciprocal altruism
when the altruist has a reasonable expectation that the sacrifice will be reciprocated in the future
need to have repeated interactions with the same individual
What are constraints of natural selection?
laws of physics, evolutionary history, trade offs, lack of variation
At what scale do human differ in their genetic make up?
A. Alleles
B. Genes
C. Chromosomes
D. Genomes
A. Alleles
Alleles
Different versions of a gene
Gene
A section of DNA that codes for a particular trait
Chromosomes
A long strand of DNA containing hundreds to thousands of genes
How many pairs of chromosomes does a person have?
23
Genome
All the genetic material an individual carries
Nucleotides
Organic molecules that make up DNA and RNA
what are the possible nucleotides in DNA?
adenine, guanine, thymine, cytosine
What are the possible nucleotides in RNA?
adenine, uracil, cytosine, and guanine
what are the nucleotide pairings in DNA?
thymine pairs with adenine, and cytosine pairs with guanine
What are the nucleotide pairings in RNA?
Uracil pairs with adenine, and cytosine pairs with guanine
The Central dogma
The flow in of genetic information through the two-step process of transcription (DNA → RNA) and translation (RNA → proteins)
DNA is (__) stranded
Double
The sense strand and the antisense strand should look the () except the ()
same; Us and Ts
what happens to the antisense strand?
It gets transcribed into RNA
What happens during translation, and where does it occur?
RNA → protein, occurs in the cytoplasm with the help of tRNA
In translation, the anticodon
binds in to the mRNA and adds their amino acid
the anticodon should be (__) to the mRNA
complementary
The genetic code won’t work well if:
there is no start/stop codon
if the stop codon is too early
Primary protein structure
Sequence of a chain of amino acids
Secondary protein structure
Hydrogen bonding of the peptide backbone causes the amino acids to fold into a repeating pattern
tertiary protein structure
3D Folding pattern of a protein due to side chain interactions
Quaternary protein structure
Protein consisting of more than one amino acid chain
Different alleles produce
Different phenotypes of the same trait
Different phenotypes can result from the
Amount of mRNA transcribed (produce more mRNA, could produce more protein → different phenotype)
different amino acid sequences
What are three of types mutations?
substitution: a nucleotide is exchanged
insertion: a nucleotide is added
deletion: a nucleotide is removed
Mutations are more likely to have an effect if they happen in
Protein coding regions
The E. coli genome is 87.8% protein coding (compared to 1.5% in humans). Which of the following would you expect to be true?
A. Mutations are mortar likely to be beneficial (increase fitness) in humans.
B. Mutations are more likely to be deleterious (causes lower fitness) in E. coli.
C. There are probably more mutations in humans
D. there are probably more mutations in E. coli
B. Mutations are more likely to be deleterious (causes lower fitness) in E. coli.
Particulate model of inheritance
Traits passed down as discrete units rather than being blended together
Law of segregation
When any individual produces gametes, the 2 copies of the genes separate so that each gamete receives only one copy
Law of independent assortment
Alleles of different genes assort independently of one another during gamete formation
what happens to one gene doesn’t affect what happens to another gene
Diploid
Having 2 copies of each chromosome (2n)
Meiosis is used for
Making gametes
What is the result of meiosis 1?
2 cells containing duplicates of 1 chromosome
What is the result of meiosis 2?
4 cello containing 1 chromosome each
What are the 3 types of dominance?
complete dominance
incomplete dominance
codominance
Complete dominance
A single dominant allele produces the dominant phenotype. the homozygous dominant and heterozygous genotypes have the same phenotype
Incomplete dominance
The heterozygote phenotype is intermediate between the two homozygous phenotypes
Codominance
The heterozygote shows both the homozygous phenotypes
Do dominant traits skip generations?
No.
Recombination
The rearrangement of genetic material, especially by crossing over in chromosomes or by artificial joining of segments of DNA from different organisms
occurs when you have two genes on the same chromosome
Is recombination more likely to occur between 2 genes that are closer together or farther apart?
Farther apart
The likelihood of recombination between two genes is proportional to
The distance between the 2 genes (on the chromosomes)
If you have two linked genes, the parental types (same chromosomes as parents) will always
Have more offspring
offspring than those that require recombination
Phenotype of offspring is entirely determined by
What kind of gameto they get from parent
Linkage mapping
Determining the recombination frequency for numerous genes allows us to map each gene's on the chromosome
One gene affects () characteristic(s)
Multiple
The ‘frizzle’ phenotype in chickens is determined by a a single gene (the F gene). Chickens with the frizzle gene also there's to have increased metabolism. What are potential explanations for this phenomenon?
A. The F gene and the metabolism gene(s) must be on different chromosomes.
B. The F gene and the metabolism gene(s) are very close together on the same chromosome
C. Pleiotropy
B. The F gene and the metabolism gene(s) are very close together on the same chromosome
Note
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