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Now that we know the frequency with which we expect A and a alleles to appear in the offspring generation when all individuals in a population have an equal probability of surviving and producing surviving offspring, let's explicitly and consciously compare them to the frequency with which these same alleles appear in the parent population and, finally, reflect on the question titling this section.

a. How does the probability (likelihood) that an allele will make it into the offspring generation compare to the frequency with which that allele occurs in the parental generation?

b. Compare your responses to Problems 1, 2a, 2c, and 3a. What do they suggest about the relationship between the frequency with which an allele appears in the parental generation, its probability of appearing in parental generation gametes, and ultimately its frequency in the offspring generation when mating is random? Why? Please explain.

As is hopefully now clear, when all individuals in a population have an equal probability of surviving and reproducing successfully the probability that an allele ends up in a fertilization event and thus, in the offspring generation is equal to the frequency with which that allele appears in the parent generation. That is, when no agents of evolution are acting on a population, the allele frequencies observed in the offspring generation will be the same as those observed in the population producing them.

In reality, would you expect offspring generation allele frequencies to always be perfectly identical to those of the parental generation when mating is random? Why or why not? Please explain.

Of course in practice, all populations are subject to genetic drift (an agent of evolution) where, just by chance, some individuals will reproduce more frequently than others making a disproportionate contribution to the next generation. This effect will be most pronounced in small populations, like that in the example above, and least in very large ones.

Test your understanding by returning to the scenario depicted in Problem 3 of the previous section. It turns out that the allele associated with increased fertility, referred to as H2, is found in 21% of the loci of people of European descent.

a. If this population is not evolving with respect to this allele, how frequently should this allele occur in this population 200 years from now? Why? Please explain.

b. Draw a figure (graph) illustrating your prediction from part a. Please make sure to label your axes and include a figure legend .

a. In the absence of any evolutionary processes including genetic drift operating on this population, this allele should still occur in 21% of the population 200 years from now. This is expected because the H2 allele currently occurs in 21% of the population's loci, consequently 21% of all 'buckets' in the population contain this allele, leading 21% of the gametes involved in fertilization events to contain the H2 allele, causing the H2 allele to occur in 21% of the loci in the next generation. This will be repeated generation after generation for 200 years in the absence of an evolutionary force.

Expected frequency of the H2 allele over a 200 year period if the European population is not evolving with respect to this allele.


  • frequency - the number of times an event or observation, for example a particular measurement or condition like blue eyes, is observed in a collection of events or observations like those comprising a sample, population or study. In this statistical sense, a frequency is equivalent to a proportion. For example, the frequency of a particular allele is equal to the number of times that allele is observed in a population over the total number of alleles for that locus in the population. Can be expressed as a fraction, a percentage, a decimal, or a probability.
  • genetic equilibrium - state of a population in which allele frequencies remain unchanged from one generation to the next.
  • legend - a one or two sentence description of the variables depicted in a figure (graph).

    Works cited

  • Stefansson, H., Helgason, A., Thorleifsson, G. et al. 2005. A common inversion under selection in Europeans. Nature Genetics . 37:129-137.

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
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for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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