Adaptive Radiation : Marsupials & Placental Mammals - Evolution, Biology, Class 12 Video Lecture

hello friends this video on evolution
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calm no more fear from exam so let us
look at another example of adaptive
radiation so here we are going to talk
about the Australian marsupials so if
you talk about these marsupials this
marsupial started as very small
creatures but later they evolved into
many different species so they are
termed as Australian marsupials because
they arrived in Australia around 55
million years ago a long time back so at
that time there are no mammals existing
in the continent of Australia so if you
look at the variety of species into
which they evolved you actually you can
actually see that they are all diverse
starting from a marsupial rat which you
can see here here you have the tiger if
you have the tiger cat here you have the
mushroom PL kangaroo so this is the moon
so that means you have a variety of
organisms right so it had even the large
animals like the marsupial kangaroo
which you can see here these red some of
the large grazing animals do you eat
there even match should be Lions which
where large predators so this is how it
all started from the marsupials and then
it radiated in so many variety of
different species so this is also an
example of adaptive radiation now there
are many close similarities between the
marsupials and the class until mammals
now first of all what our class until
mammals so there are quite a few
similarities which were seen between the
marsupials and
classical novels are those mammals in
which for the first time the development
of classic nervously back glass endure
is that tissue which connects the mother
to the baby which is present inside the
mother's body so the development of
placenta happened for the first time in
these mammals and they were called
placental mammals so how we will look at
some of the examples where we will see
that how these two went closely related
to each other and how do we know that
they came from the same ancestor long
time back so marsupials in Australia and
placental mammals in North America they
exhibit similarities so we can see that
they both occupy different geographic
location so one of them in Australia the
other one in North America but it has
been seen that both adopted adapted in
similar ways to particular food supply
locomotory skill or climate and also
been looking at their behavior and
looking at their structure the way they
are it can be assumed that they were
separated from some common ancestor
millions of years ago so despite the
geographic separation between the two
both produced varieties of species
leading to similar habitats with similar
range of life so we will see water by
the various varieties of species which
evolved from placental mammals so in the
last slide we saw the marsupials that
how different types of species were
being formed from the marsupials so let
us have a look here so so if you take
the example of mice so whether you
consider a marsupial rat or a placental
mammal Mines
so if you compare both of them you would
see that both of them inhabit the low
shrubs and they move around at night
or insert your food items they both are
also similar in size as well as shape if
you talk about the molds and if you
compare the marsupial rolls with the
plastic salvos you would see that both
of them burrow into the soil and lift
they eat insects they have fur over
their body which help in movement
through the soil so that makes their
movement smooth through them so I you
also take the example of the marsupial
wolf or the mammalian would you class
until wolf there also you will see that
both of them are carnivores they have
limb bones which are adapted for running
and that is why they are able to run
very fast to catch their prey they have
sharp teeth which help in tearing meat
and that is why again it is related to
their food habit that is they are
carnivores
however this Tasmanian wolf have become
extinct in fact the last hasmonean wolf
had died in 1936 so it has become
extinct now but all these marsupial
animals which you see they have a close
relation with the placental mammals even
though they exhibit two different
geographic locations of the world and
why is it so what does this similarity
say they say that they would have shared
a common ancestor normal and back and
after that they would have started
inhabiting different locations so even
after inhabiting different locations
they are continuously evolving and
giving rise to different species in that
particular location so what do we get to
know from our discussion and adaptive
radiation that species branch out to
occupy multiple niches and evolve into
multiple species because all the species
want to survive and in order to survive
they try to search out for more options
they try to adapt to get food they try
to adapt to get shelter for themselves
so adaptive radiation is seen to be most
successful during mass extinctions or
when a species entirely get extinct or
when polarizing and unhappy did Island
for example there of the Galapagos
Islands so this that island was either
not in happy
my the birds so they came for the first
height so they migrated from some other
place due to a storm they had to come
there and when they came there so
adaptive radiation became very
successful with them because there
everything was suitable for them to
survive and as a result they underwent
reproduction very fast so more and more
organisms reproduce when the number of
organisms are more the variety is also
own which can cause evolution which can
give rise to different species of the
organisms so this was all about adaptive
radiation thank you please visit exam
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