Evidence from Moths Propagation Video Lecture - Biology Class 12 - NEET

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the next evidence as I said this
evidences from England on population of
months so mods are those insects which
to some extent to example the butter
friends so it was seen this is like a
story now it was seen in some place in
England in around 1850s that the
population of the mods changed over a
period of time now before
industrialization came in that means
before the industry set up and so much
of industrialization had happened that
time the population of wants were little
different but post industrialization it
became just the opposite
so that is that has also acted as an
evidence for evolution so let us see
what had happened the pre
industrialization in a particular area
in England it was found that the white
beamed moths had a bigger population
that the dark winged modes there are
there were two varieties of moths which
were seeing that time but more
widespread was the white wait the moths
which had white wing and to see that
there were very few moths with dark P so
somewhat like this and degenerates moths
are found or the tree box so more of the
white winged moths were present so these
were more prevalent when compared to
them dark winged mode so here you see
they are white wings and here this dark
paint now what happened free
industrializing but later post
industrialization the scenario became
just the opposite so after
industrialization it was seen that the
population of the dark paint wants
was larger when compared to the white
wing wants so the question was how did
industrialize
affect the population of the Mons so how
come the dark winged modes increased in
number and the wiping mods decreased in
number so what went wrong
now what happened was pre
industrialization before
industrialization came into picture so
there was not much of pollution so there
were no spewed from the industries and
also there were white growth of lichens
all over the tree trunks so on the tree
trunks we could see the lichen like in
is nothing but the mutual or symbiotic
association between the fungi and the
algae now due to the presence of those
white white layer you can say the tree
bark
used to be lighter in color now when the
bark was lighter in color it used to
happen that the white colored moths when
length it's visible on them so if you
see this mod is less visible when
compared to this one so this is a dark
mark so which is the contrast color when
compared to the background which is
almost white due to the presence of
light so what happened these became
easier for the Predators so elegantly
natives came for their prey for example
the bats or the outer sphere one of the
Grenadiers which used to feed on the
moths so whenever the owl came in search
of a place it was easier for the album
to find out the brown wig moth because
it was clearly visible but the white
winged month because it had the same
color as that of the background it was
difficult for the owl to find out a
white winged month so I have what
happened most of the time the brown
winged moth was being caught and it was
being eaten up by the out so as a result
the population of the Brown being moths
reduced and as I said the population of
the white wing was relatively increased
and therefore the white wing modes had a
bigger box addition when compared to
them that wing once because the survival
rate of the white winged modes was
greater than that of the dark pink modes
now the situation changed if angels the
opposite post industrialization after
industry
what happened was that due to pollution
and also there was no lichen growth in
presence of the industries so as a
result due to pollution at all the tree
barks became darker so the trunks were
now darker in color so as inside the
brown winged moth now was almost like of
the same color as that of the background
so it was difficult to find out a brown
winged moth but the white moth became
very much noticeable so it could be
easily caught by the predator so now
when the owl came in search of a plane
it could easily spot a white winged
month but the brown big moth was not
caught because it was not distinctly
seen so as inside the out started frames
on them by embankment therefore the
population of the right pane was reduced
and as a result the population of the
brown winged moth increased so here you
can see that as a result of
industrialization or what why is there a
change in the population so now if you
see from the white winged North with
over a period of time with the passage
of time
the white pink North vanished out
because after industrialization they
were all eaten up so gradually their
population kept on decreasing and the
brown wing north kept on increasing so
in a way you can say that brown wing
mark these born from the white winged
mode so while being worked was the past
so it is saying it will become extinct
by the brown pink moth will be there so
this is also an example or this is also
an evidence which talks about evolution
which tells that there can be many
different variety of organisms living at
the same time but there can be many
different environmental factors
environmental factors or the Predators
can also be of course so there can be
many different causes because of which
some of the organisms continue to
survive some of the organisms they are
they just get lost so they just die off
and they become extinct so this is now
example of a value in not example this
is neither evidence which talks about
evolution so this is how also new
organisms can evolve so here you can see
the brown wing moth evolved because
earlier by it being worth less word
prevalent but due to different scenarios
or you do under a special situation the
brown winged moth became more prevalent
so now the last one is the evidence of
resistant variety of organisms now I am
sure that many of you would have seen
the insect repellent cockroach repellent
or the mosquito repellent which you
commonly use in your house in order to
get rid of cockroaches and mosquitoes
you would have also seen or heard of the
insecticides and the best asides which
are normally sprayed in the farms to
kill the incense and the pests now what
happens by then why does it happen that
when you spray it the insects or the
pests they aren't dying that's because
as soon as it is friend they are not
resist their body is not resistant in
those chemicals and as a result it
spoils their their the entire balance of
the body and they die so that is what
normally happens but if you start using
pesticides in an excessive amount if
repeatedly you keep using these kind of
pesticides sometimes what happens is
that some resistant variety of organisms
evolve so some such organisms one or two
who might come up which become resistant
with those sprays so let us suppose that
these are the bugs and you want to get
rid of these bugs
so you use a spray now as soon as you
give this plane so most of them died so
the 90% of them died except for one so
the one survives now why did this one
survived that's because this particular
bug is resistant to this pesticide now
why it became resistant now that can be
due to many reasons it might be possible
that some mutations of genetic mutation
has happened and as a result it has died
resistant resistance against the spring
it is also possible that it is it is
just a matter of chance that by chance
it this one did not die and it could
actually adjust with the strength so
whatever the reason may be the basic
causes that this particular bug is
resistant to this strain and it survived
so that means even if you say this this
particular pesticide on it it is not
going to die at any cost because it is
resistant to it now what wiII happen
this particular insect that will again
reproduce and it will you give birth to
its offsprings right like as we have
studied in genetics so there are chances
that this this particular insect is
going to transfer or it is going to send
or transmit the same thing into his
offsprings now as a result over a period
of time maybe it will produce one or two
more insects which will be resistant
with this particular spray again those
insects will reproduce so they might
also produce a one or two insects which
will be resistant now over a period of
time we will see that a lot of insects
have been produced which is is tend to
this spray so this resistant variety
organisms are produced as a result of
what it is produced as a desired of
evolution that's because initially the
insects which used to be there they were
not resistant to the space used to dive
in this was sprayed but due to some
reason why but here insect was formed
which was resistant to the spray and
then over a period of time that
particular insect gave rise to multiple
other insects so this type of evolution
which is caused by humans is known as
anthropogenic evolution so here you can
see that resistant organisms will appear
over months or years now again as I said
it is not necessary that it will take
millions of years for this resistant
variety of organisms to be produced
generally these insects
got shorter lifespan now when they have
shortened lifespan what happens so one
can say clips its entire lifespan and
meanwhile it produces a lot of tree
produces and a lot of you insects at
reduced right now in this case now these
resistant organisms which are being
introduced they are produced over months
or maximum over years so over the years
itself you can actually see that new
resistant variety of organisms are being
produced that means evolution is taking
place evolution is continuously
happening so it doesn't take centuries
to take to see resistant organisms over
Squam period of time only you can see
these new morality of organisms now it
generally happens due to excessive use
of insecticides or pesticides against
some specific organisms or insects so
this type of evolution is termed as
anthropogenic evolution now what is the
meaning of anthro so anthropogenic this
means something which is caused by
humans or caused by human activity so
here if you see what does the human
activity the use of take insecticides or
thus pesticides so when you use this
insecticides or pesticides if excess
only then these kind of resistant
variety formation take place so that is
why this evolution is called
anthropogenic action so in this section
we saw that there are quite a few
evidences which tell us that evolution
happens and evolution happens
continuously this resistant variety of
organisms being produced over a couple
of months or years that shows that
proves it because these kind of
organisms were not there before so a new
type of organisms are being produced
from the existing organisms so that is
one next is looking at the morphology
and Anatomy you can see that there are
many structures in different types of
organisms which are exactly
similar in structure or exactly similar
in function which shows that there is
some link between those organisms
letters they might share some common
ancestor and that is how we can say that
evolution is happening that means from
the same ancestor so in our ideas of
organisms have in form so that is
evolution we get we also saw that with
regarding the moths evidence we saw that
earlier there there were most divided
winged words and suddenly over a period
of time you could see the herb the dark
colored wings walls and that was also a
result of evolution so all these
examples and also the fossils so all the
examples together tell that if evolution
is not a hypothetical or hell imaginary
concept it is something which is
actually happening and it is happening
continuously so even though you volution
is taking place it has not stopped thank
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