hello! since being stuck at home, I have
decided to take up an interest in
reading, and I would like to improve my
book population. I have several different
lengths of books in my collection, but I
want to become a better reader and
increase the amount of pages per book. I
have selected the top 10% of my
population to breed, which are the books
with the most pages. the broad sense and
realized heritability of my phenotype of
interest are given. the trait for page
numbers resembles a normal distribution,
so to help explain my mass selection experiment,
I made a histogram with the terms and
calculations labeled. the orange curve
represents the original population and
the green curve represents the offspring
population after breeding. my original
population has a mean of 214 pages and a
standard deviation value of 55.8. this XT
symbol represents the truncation point,
which shows the standard method in
selective breeding that I used to select
the 10% of the population to be made for
the next generation. I calculated it by
using the standardized selection point (z)
for 10% of the population and then the
standard deviation and mean, which is
equal to 285.54 pages. the S symbol
represents the selection differential
and it shows the difference between the
mean of the selected parents and the
mean of the original population. I can
calculate by using the selection
intensity value (I) for 10% along with the
standard deviation to give me 97.93.
now I can find
the mean of the selected parents of the
top 10% and it's identified using the
selection differential and the mean of
the original book population. next we
have the response from selection, which
shows the difference between the
original population mean and the mean of
the offspring. I calculated using the
realized heritability of the phenotype
and the selection differential to give
us 65.61.
and from all the previous
calculations, we can now find the mean of
the offspring using the mean of the
original population and the response
value. and this is 279.61 pages, which
is a greater value than the original
population, indicating there is a higher
number of pages per book in the
offspring population. which is what we
wanted! assuming I can continue this mass
selection experiment indefinitely, the
later rounds of selection will have a
decrease in the R value or a response,
because there will be a decrease in the
genetic variance of the population, where
all the books will have the similar
trait of having more pages. so the mean
of the offspring will not be as
different from the mean of the original
population.
