evolution Flashcards
what is evolution
is the cumulative change in a population or species over time
what is natural selection
the process where species adapt to their environment by producing advantagous phenotypes to be best suited to their ecological area/ environment
what is adaptation
adaptation is the biological mechanism by which organisms adjust to new environments or to changes in their current environment.
when does adaptation occurs
when there are
- environmental changes
- some individuals carry advantageous alleles
what individuals favour natural selection
Natural selection favoured the individuals that best suited their environments
what happens over time due to natural selection
evolution
what is the difference between natural selection and evolution
Natural selection Is a driver of evolution and acts on heritable variation within a population
whereas
* Evolution is the cumulative change in a population or species over time
what is microevolution
studies the evolutionary agents of change that shape the genome of a species
what is macroevolution
changes that occur among large taxonomic groups
what are the agents of change
natural selection
mutation
sexual reproduction
genetic drift
gene flow
what is a population
A population is a group of organisms that interact and share genetic information
what is a gene pool
Is the genetic information in a population carried by a population and is dynamic
a large gene pool means
greater diversity
a small gene pool means
less genetic diversity
what does genetic diversity decribe
Genetic diversity is a way to describe genetic variation within a gene pool of a population
what does the hardy weinburg theorm explain
The hardy Weinberg theorem explains why dominate genes are not the phenotype in a population
what does the HW give us
The HW gives us the genotype frequencies expected for any possible set of allele frequencies
a population will remain in equilibrium if what HW conditions are met
1) No change in the DNA sequence,
(2) No migration
(3) A very large population size
(4) Random mating
5) No natural selection
what is the HW equation
P^2+ 2pq+ q^2 =1
what do allele frequences always add up to
1
what is the equation for allele frequences
p+q=1
what is the equation of p frequencies
f(BB) + 0.5(FBb)
what is the equation for q frequencies
f(bb) + 0.5(Bb)
what are the 3 main points of natural selection
variation
heredity
selection
what ways can selection act on a population
direction selection (positive)
stabilizing selection
distruptive selection
what is direction selection
Favours individuals on one end of the distribution of phenotypes
for example small fish have higher fitness then large fish
what is stabilizing selection
Favours individuals in the middle of the distribution of phenotypes present in a population for example acting against individuals at either extreme
what is disruptive selection
Favours individuals at wither end of the distribution
does selection favour dominant alleles or recessive alleles
Selection acts on dominate alleles faster then recessive alleles
what is fitness
Fitness: the success of an organism at surviving and reproducing and thus contributing offspring to future generations
what are the 2 types of mutations
induced and spontaneous
what type of cells can mutation effect
somatic and germline cells
how does a mutation affect a somatic cell
- Affects all daughter cells of a single cell
Not heritable
how does a mutation affect a germline cell
- Affects gametes
- Mutations transmitted via sexual reproduction
Mutations in the germline create new variation (alleles) and can be heritable
how do mutations affect a population
They may impact on an organisms phenotype
what is a small change mutation
a mutation that affects the sequence of nucleotides
what is a large change mutation
a mutation that affects a chromosome
small change mutations
- More common but less genetic consequence
- Single base changes=substitution
= point mutations
Insertion and deletion affects the amino acid sequence
large change mutation
- If DNA is copied twice or flipped around
- Chromosomes are joined together or gained/lost (aneuploidy)
Entire genomes are duplicated
mutations on regulatory regions affect
affect expression
mutations in the coding regions affects
affects protein function
what are the 2 modes of transferring genetic infomation
asexual and sexual
what is random mating
equal probability that mating will occur between any two indivduals in a population
what is non random mating
mating where there is a probability of bias
how can mating systems influence evolution
mating systems can influence evolution by assortive mating and disasortative mating
what is assortative mating
positive assortative (mating between like and like so white horse with white horse
- Inbreeding
- Less genotype diversity
- Increase homozygosity
what is disassortative mating
- Disassortative mating: negative assortive (making between a white horse and a black horse)
- Increase genetic diversity
More heterozygosity
- Increase genetic diversity
what is genetic drift
changesin allele frequencies of an allele variant due to random chance
how does genetic drift influence small populations
genetic drift is a stronger evolutionary agent of change
* Outcomes are more unpredictable
Probability of larger change is greater
how does genetic drift affect larger populations
- Larger populations buffer genetic drift making it a less significant agent of change
Populations don’t need to be infinite size but large enough that random sampling effects do not impact allele frequencies
what populations does genetic drift affect more
· Genetic drift affects small populations over larger populations
what is the bottle neck affect
Population goes through a severe reduction where only a few member survive
what is the founder effect
Smaller group from a larger population creates a new distinct population
results in migration
what is the consequences of gene flow
Introduce new genetic variation
Reintroduce old genetic material from re-existing alleles
what is migration
between distinct populations and occurs at larger levels
what is movement
between subset populations
how does gene flow occur
· Individuals needs to interbreed and produce viable offspring
If individuals like to mate disassortative gene flow is more likely to be achieved
-this is done by migration of populations which introduce new allele frequencies
what is the equation for the change in frequency of the resident population after one genetation of migration
/\p=m(x-p)
m= migration rate
x=frequency of a population f(A) - migrants
p=frequency of residents
gene flow has a large impact on the gene pool when a population
-migration rate (m) is high
when allele frequencies in residents (p) is migrates (x) differ
what are barriers preventing gene flow
premating isolation
prezygotic isolation
postzygotic isolation
what is premating isolation
geographical isolation and behavioural isolation
what is prezygotic isolation
mating time differences and ecological differences
what is postzygotic isolation
fertilized egg/offspring inviable
what is allopatric speciation
speciation in different geographical locations
what is sympatric speciation
speciation in the same location
what are the 2 types of sequencing
moleular and genomics
how do you sequence a reference genome
Extract DNA
create sample DNA
sample
analylse
(ellie created sex addicts)
