Microevolution: Variation, mutation, HWE and Natural selection (W2,L4) Flashcards
Microevolution VS. Macroevolution
Natural selection
Rock pocket mouse and relationship with Natural selection
Genotypes VS. phenotype
What is Microevolution?
Changes in genetic characteristics (allele frequencies) of a population over time
What is Macroevolution?
Descent of different species from a common ancestor over many generations
evolution is descent with modification, which implies multiple generation
all individuals from the same population are same species?
A population is a group of individuals of the same species that live in the same geographic area that interbreed with each other. Many species consist of multiple populations dispersed over a few to many geographic areas.
what is Allele? where is allele located at and how many allele does human have?
is a variant form of a gene. For example: Humans are called diploid organisms
because they have two alleles at each genetic locus, with one allele inherited from each
parent. Each pair of alleles represents the genotype of a specific gene.
alleles are matching genes; one from our biological mother, one from our biological father. We have two copies of every gene (strings of code that drive some biological function on our chromosomes). They can be identical, but they can often have slight differences
diploid organisms
Diploid is a term that refers to the presence of two complete sets of chromosomes in an organism’s cells, with each parent contributing a chromosome to each pair. Humans are diploid, and most of the body’s cells contain 23 chromosomes pairs
what does allele are dominant or recessive mean?
Some alleles are dominant or recessive. When an organism is heterozygous at a specific
locus and carries one dominant and one recessive allele, the organism will express the
dominant phenotype. e.g. A,a, B,b
Dominant refers to the relationship between two versions of a gene. Individuals receive two versions of each gene, known as alleles, from each parent. If the alleles of a gene are different, one allele will be expressed; it is the dominant gene. The effect of the other allele, called recessive, is masked.
heterozygous? example?
The presence of two different alleles at a particular gene locus. A heterozygous genotype may include one normal allele and one mutated allele or two different mutated alleles
If the two versions are different, you have a heterozygous genotype for that gene. For example, being heterozygous for hair color could mean you have one allele for red hair and one allele for brown hair. The relationship between the two alleles affects which traits are expressed.
Locus?
(LOH-kus) The physical site or location of a specific gene on a chromosome.
Genetic variation? example?
the number and relative frequency of alleles that are present in a
particular population
For example, if we look at eye colour, people with blue eyes have one allele of the gene for eye colour, whereas people with brown eyes will have a different allele of the gene
How does genetic variation affect on population?
Genetic variations that alter gene activity or protein function can introduce different traits in an organism. If a trait is advantageous and helps the individual survive and reproduce, the genetic variation is more likely to be passed to the next generation (a process known as natural selection).
Mutation
: A mutation is a change in a genetic sequence, i.e. introducing new alleles
Mutations are a source of genetic variation
Mutations are random- they occur irrespective of their potential usefulness (benefit) to an organism
Random processes= indifferent processes
How does mutation effect on population?
Mutations can introduce new alleles into a population of organisms and increase the population’s genetic variation.
Evolution
is a change in the allele frequencies of a population over time
Genotype
the genetic makeup of an organism
Phenotype
is the detectable expression of genotype
physical traits that are a product of the proteins produced
Why is variation in populations important?
If evolution is change in a population’s traits
over time, then traits need to vary in a
population
Rock pocket mouse
(Chaetodipus intermedius): lives in the deserts
of southwestern U.S. most have a sandy, light-colored coat but some have dark coats
how does genetic variation occur?
Genetic variations can arise from gene variants (also called mutations) or from a normal process in which genetic material is rearranged as a cell is getting ready to divide (known as genetic recombination). Genetic variations that alter gene activity or protein function can introduce different traits in an organism.
what process can generate new alleles
mutation
sexual reproduction
sexual reproduction, the production of new organisms by the combination of genetic information of two individuals of different sexes. In most species the genetic information is carried on chromosomes in the nucleus of reproductive cells called gametes, which then fuse to form a diploid zygote.
what is can alter a gene’s products ?
mutation
What is the process of genotype into the phenotype?
what is the information storage?
DNA
What is the information carrier?
mRNA
What is the melanocortin receptor?
proteins
explain transcription step? when does it happen? how does it happen? where does it happen? why does it happen?
explain translation step? when does it happen? how does it happen? where does it happen? why does it happen?
Q1: Most of the deserts have light coloured sand and granite, but here
and there are patches of dark volcanic rock, separated by several
kilometres of lighter sand. Did the appearance of dark-coloured
volcanic rock cause the mutation for black fur to appear in the rock
pocket mouse population? Explain.
Can individuals with different genotypes exhibit the same phenotype?
Since the phenotype is the result of an interaction between genes and the environment, different environments can lead to different traits in individuals with a particular genotype. In addition, different genotypes can lead to the same phenotype. This happens because genes have different alleles.
Can individuals with same genotypes exhibit the different phenotypes?
yes, because of environmental differences and interactions between genes and environment
Null hypothesis?
The statistical hypothesis that states that there will be no differences between observed and expected data.
➢Hardy-Weinberg Equilibrium mean ?
In population genetics, the Hardy–Weinberg principle, also known as the Hardy–Weinberg equilibrium, model, theorem, or law, states that allele and genotype frequencies in a population will remain constant from generation to generation in the absence of other evolutionary influences.
change in genetic characteristics of a population over time is definition of ?
evolution
➢ A gene with two alleles, A1
and A2
➢The frequency of A1
is represented by p and the frequency of A2
is
represented by q in the gene pool.
➢ Because there are only two alleles, p + q = 1. These are the frequencies of
the two alleles, which sum to 1 (or 100% of the population).
Allele frequency?
relative abundance of different alleles for a gene within a population
Genotype frequency
percentage of individuals (relative abundance) in a population possessing each genotype for a given locus (gene)
what is null model use for?
Use controls in experiments to evaluate effects of a particular
condition
✓ Use null models in observational studies (because no suitable control)
Null models → predict what we’d see if particular factor has no impact
