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Category: Biology
Tags: adaptationecologyevolutionfitnessselection
Entities: adaptationbee hummingbirdcheetahecologyevolutionGalapagos finchesimpalanatural selectionpeppered mothzebra
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[Music] [Music] namaste we are the products of evolution
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life began on this earth roughly 4 billion years back and whatever life forms we observed now whether it's trees whether it's Birds animals even us we are all the products of evolution now in this lecture we are going to have a look whether ecology has any relation with
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evolution so let us begin with some key terms as we saw before ecology is the scientific study of interaction among organisms and their environments and here we need to emphasize on the word interactions so we are studying the
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interactions among the organisms and their environment where is evolution the process through which we have all been made it is the genetic adaptation of organisms to their environment now in this case we need to look into these two
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terms genetic adaptation what is genetic what is adaptation and how are these related to evolution now adaptation is any alteration in the structure or function of an organism by which the organism becomes better able to survive
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and multiply in its environment so adaptation is any alteration alteration is changes any change in the structure of an organism or the function of an organism so for instance if in place of hands if I develop wings so that would
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be a change in the structure or for instance a change in the function would be in place of using my hands for writing if maybe I start using it for something else so probably for instance I develop some other sense organs on this hand so that
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I can spell these objects by taking them so that would be a change in the function of an organ now any such changes in any organism or any Ahlan of the organism by which the organism becomes better able to survive n
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multiply unit cell so any changes will not be adaptation a change or an alteration is an adaptation only when it permits the organism to better survive in that environment better survive and to better multiply in
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that environment so for instance classical examples of adaptations are now the camel lives in a desert environment now in that desert environment you have mounds and mounds of sand and there you have a camel now
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what are the kinds of adaptations that you will find in this animal one is that it has a hump now why does it have a hump the hump stores energy in the form
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of facts and water oh no why why is that required because when you are living in a desert environment you don't have a very ready access to water and food so if you have ever seen a camel drinking it would
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drink buckets in buckets of water and store all of that into its body and the urine that this animal releases out is a very concentrated unit because it is
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trying to save all of that water inside its body if it loses out that water it won't have access to that water again similarly if you look at the blood of the animal it has the characteristic
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that even if it has lost quite a lot of water it will still be able to pump this blood into the body and be able to to bring nutrients to the cells and take out the waste materials similarly if you look at the legs so the legs are padded
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now why are they padded because if you consider a leg that is say like this and a leg that is padded and has a larger surface area so now if this area is a and this area is capital a we are
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talking about these areas if the weight of the animal is say X kg the amount of downwards force that that is being put on the legs is X into G where G is the acceleration due to
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gravity approximately nine point eight meter per second square now this much amount of force that is acting downwards is divided in by the four legs so and the the pressure that
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would be exerted by this force that is X into G by 4 on each interface between the leg and the sand would be given by X by G by X into G by 4a in the first case
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and X into G by four eight in the second case now in this particular example if a is large so in that case the pressure would be less so if you have less amount of pressure how it helps is that if you
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have this sand and if you have a pointed leg it will go inside the sand whereas if you have a padded leg then because the the amount of pressure is less so the animal will be able to walk on this sand so this is also another adaptation that is there in the animal then if you
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look at the eyes of the animal you would observe that the eyes have very large eyelashes now these eyelashes prevent sand from getting into the eyes of the animal if you look at its tongue or even
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its mouth it will be be very well-suited to eat the kinds of vegetation that are present in the desert environment so these are all different kinds of of adaptations that this animal has and all these adaptations are permitting this animal to better survive in this
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environment now genetic means relating to genes or heredity so basically all of these adaptations they should be of such a manner that they get passed on from
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one organism to its offspring to their offspring and so on so which means that all of these adaptations have to be heritable adaptations so if you have a camel that
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for instance has feet that are even better adapted then most of its companions and if this trait is not able to be be passed down to its offspring it won't be called a genetic adaptation so what we want in the case of evolution is
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genetic adaptations or inheritable fitnesses that permit the anvil to better survive and better reproduce now we have introduced this term fitness and fitness refers to the ability of a particular organism to live descendants
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in future generations relative to other organisms and evolution tends to maximize Fitness through the process of natural selection so basically Fitness's the ability of an animal or an organism to live descendants in the future generations
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relative to other organisms which means that it should be able to leave more number of descendants as compared to any other organism of the same species that is there in the environment so for instance you have two individuals you have this individual a and this
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individual B and suppose you have individual a that has produced ten offsprings individual B has produced hundred offsprings and all of these are able to survive to their maturity so
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here you have ten and here you have 100 so in this case we would say that organism B has a better amount of fitness as compared to organism E because it left 100 offsprings whereas a was only able to live ten offsprings but
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suppose out of these 10 offsprings nine were able to survive and out of these hundred offsprings only seven were able to survive why because organism a was able to devote all its time and attention to all
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of its ten offsprings so that nine survived whereas B just produced more number of offsprings and it did not give it any parental care and so only seven survived to the next generation so in that case we would say that a is having more amount of fitness as compared to B because it left more number of
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offsprings to the next generation now why is that important it is important because evolution tends to maximize the fitness through the process of natural selection what we mean by this is that evolution will always prefer evolution
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prefers better fitness why because if organism a has those characteristics which are inheritable and because of which it was able to leave more number
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of offsprings so all of these nine office pairings will also be getting those characters from a and so all of these nine or most of these nine organisms will be able to leave even more number of offsprings in the next generation as compared to B so in the
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case of B out of 100 only seven survived out of these are the in very few number would survive so after a while we would observed that in this system we'll be having more number of organism with a kind of characteristics as
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compared to be kind of characteristic so evolution tends to maximize the fitness that is present now what are the characteristics of this Fitness so Fitness is environment specific so we do not have an absolute value of Fitness it
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is environment specific so for instance in the case of our organisms a and B in one environment it is possible so let us consider an environment in which there is more amount of predation now in this
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environment if you are able to protect your offsprings you will be able to have more number of offsprings in the next generation whereas if you are not able to protect your office Springs most of the office prints would die off but then in an environment in which you do not have any predation
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you have ample resources as compared to the population so in that case you do not require very much amount of parental care that needs to be given to the office Springs so in that case this organism B that was able to have more
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number of offsprings would be said to be be more fit as compared to organism a that only gave 10 individuals because in the absence of predation in the absence of diseases when you have ample amount of resources available most of the office films are able to survive so in
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such situations just producing more number of office films would give you a bit of amount of fitness so in this example we saw that Fitness environment is specific it depends on how harsh the environment is secondly fitnesses species is specific so we do
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not compare Fitness's between two different species high reproductive rate alone does not mean higher fitness but higher survival of more progeny does so as we saw before it if you have more number of offspring it does not mean that you have more amount of Fitness what is important is how many of those
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offsprings are able to survive to the next generation then Fitness should be measured across several generations it is a long-term measure so we cannot determine Fitness in just one or two generations it has to be determined over a long period of time and it works at
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the level of complete organism not on individual traits such as size or speed so essentially if you have two organisms in one organism is faster than the second organism organism will be more fit because we will have to look at all
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the characteristics that are present in that organism so it is possible that the organism that has speed also has more amount of blood pressure and so it dies off quickly as compared to the second organism so in that case we will say
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that speed is alone insufficient to give fitness to the organism so all the characteristics of the organism need to be looked in totality next we said that natural selection is the mechanism through which more fit organisms are
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selected so how do we define national select it is the process in nature by which only those organisms that are best adapted to their environment tend to survive and transmit their genetic characteristics to the succeeding generations while those less adapted
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tend to be eliminated so natural selection is the process through which nature is selecting those organisms that are better fitted to the environment and there are five stages in natural selection the first stage is called variation all individuals are not
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identical they have different characteristics so for instance if we look at a class of students we would find that we have students of different heights or we have students of different weights or different skin color or different color of the hair or different
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eye color so these are all variations that are found in a population now natural selection when it's when it wants to select those organisms that are the best fit so in essence it also means that you need to have some variations if
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all the organisms are one and the same then you cannot select between these two organisms so we have variations that are present in organisms and a classical example is that of peppered moth so this is a moth and it is present in two varieties one is this dark colored moth
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and the second is this light colored version so these belong to the same species but they have different colors the second step of natural selection is over population now over population means that organisms tend to produce excess number of offsprings so for
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example female mosquitoes may lay five hundred a month to 1,000 eggs now if you had a situation in which every two organisms after meeting they only produced two
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office Springs which upon meeting again produced only to offer Springs so in such a situation will observe that
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the population is not growing the population is static because for every two of organisms in this generation say g1 you only have two offsprings in the second generation g2 for these two
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organisms in the second generation you only have these two office Springs so in this case you'll have a situation in which with time the number of organisms
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will remain constant with time they will not be any change however it is observed that if you provide ample amount of resources to any organism it tends to overpopulate so overpopulation means that from one organism in the first or
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say from two organisms in the first generation the second generation may be having certain organisms the next in place of having the first one had two organisms this again had tangent organisms so it was a multiplication factor of five if you do this multiplication factor of five again then
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in place of ten you will be having 50 organisms next you will be having 250 organisms and so you'll have a curve that is arising exponentially now in nature what we observe is that organisms tend to produce excess offspring so most
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of the organisms into for an exponential curve but the problem with that exponential curve is that you do not have ample resources to accommodate all of these organisms so there will be a struggle for existence the resources are
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limited so not all of strings will be accommodated and when that is a situation then you will have some individuals that will have to be eliminated now we went to Kruger National Park in 2018 and they will
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observe cheetahs that were hunting so now let us have a look at how this hunting happens to understand better what is the struggle for existence
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so that is the voice of our tour operator and we are observing cheetahs that are hunting impalas now impalas are deer that are found in South Africa and as we can observe here this cheetah is moving in a stealth pattern so it's
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moving very slowly it's moving very cautiously towards the impalas which are the prey of this animal and now it has started running and the prey or the impalas are also running and there we
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see another cheetah so in fact these cheetahs were hunting in groups so we had four cheetahs in this particular group the impalas were also there in a group the cheetahs tried to run after the impalas but even after running and even after
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spitting quite a large amount of energy doing the stealth operation and running they were not able to catch any Impala so that tells us the struggle for existence we have four cheetahs here but they will not get food every day so out
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of this struggle for existence if there is out of these four cheetahs if there is a cheetah that is not able to tolerate hunger or falls prey to our disease because it's not getting enough amount of food so it will be eliminated from the nature so only those that are
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the best fitted will survive to the next generation which brings us to the fourth step of national selection which is survival of the fittest only those individuals best are able to obtain and use resources will survive and reproduce so for instance even in the case of
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these four cheetahs after hunting a prey if you figured out that one of these four brothers was able to do to get the largest amount of meat and there was another one that was not able to get enough amount of meat so in that case
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you will have the first cheetah that would be able to survive better asking does not get enough amount of food so survival of the fittest means that only those individuals that are besties to obtain and use resources we'll survive and reproduce so getting resources is crucial for the
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survival of an organism and only when this organism survives breeds and produces more number of office Springs will we say that this organism is fit and will be selected in the process of natural selection now the fifth step in natural selection is changes in the gene
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pool so inherited characters increase the frequency of favorite traits in the population now what is changes in the gene pool so we come back to this example of the peppered moth now we saw before that this peppered moth is present in two color variations one is
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the dark color and one is the light color now this example comes from England and before the Industrial Revolution the trees the area was very pollution free so trees had a lot of
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lichens on their surface and these whitish color are the lichens so lichens provided the bark of the tree lighter shade and on this lighter colored bark we can observe this insect but we cannot observe this insect as easily so we also
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have a lighter colored in SiC a lighter colored peppered moth that is there on this bark but we are not able to see it very easily now many industrial division came so there was quite a lot of of air pollution in that area and pollution
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killed of the lichens so if this lichen gets removed from the box so the Box get exposed and probably you'll also find some amount of soot on these box now when that happens this lighter colored version which was earlier very much
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camouflaged on the lichens is now clearly visible where is this dark colored version now it becomes camouflaged in this image as well we have two peppered moths and we are very easily able to see this peppered moth but not this peppered moth now how is
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that important that is important because in these situations when you have an unpolluted atmosphere when you have quite a lot of lichens on the trees these dark-colored individuals are preferentially predated so if there is a
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bird that feeds on peppered moths and if it will it's this tree it would be able to observe this peppered moth but not this one so it will eat up this one and this one will be saved whereas in the case of a polluted environment we would observe that this one is very clearly visible but this one
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gets camouflaged so this will be preferentially Peter so when it was observed that across generations with time what was the proportion of this dark-colored allele and what was
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the proportion of the light-colored allele in the population this is how it went link number or let us say proportion of Elise so let us divide this period into stages so the first
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stages before Industrial Revolution the second one is during and after Industrial Revolution and the third one
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is after Clean Air Act was passed now in the first period before Industrial Revolution we had a situation like this
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one now in this situation it so happened that most of the dark-colored peppered moths were eaten up and so their numbers were very less most of the peppered moths that you would observe would be light in so before Industrial Revolution you have this dark color variety which
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is very less and you have the light-colored variety that is very high now during and after the Industrial Revolution the light ones were were preferentially eaten up and the black ones but were spared so after a few
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generations it so happened that the number of dark-colored moths in the pollution increased and the light colors reduced now once we had quite a lot of
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air pollution and we had situations of public outcry especially after the great Lenin smog we had the passage of a Clean Air Act's through which the amount of pollution in the air was regulated once that happened
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and when once the air cleaned up again the situation again reverted back to this situation so we had less amount of pollutant so lichens again came up on the trees and again we had situations in which the dark-colored must be preferentially eaten so in that case we
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again got to a situation in which the number of dark colored moths reduced in proportion and the number of light colored watts increased in proportion so what we are observing here is changes in the gene pool so this is a very good
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example of how natural selection operates in principle so in this example we can see that there is variation in the organism so different individuals different colors now peppered moths like
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most other organisms also produce a number of Springs so there is overpopulation there is struggle for resources now if this was the only tree that was available and if these two paper wasps were the only two peppered
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moths that were available so this peppered moths would have resided here and this peppered moth would have moved to this location in which case both of these peppered moths would have been spared from predation and both would have been able to live equally well however because there is a
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struggle for resources because we because there is a dearth of resources as compared to the number of organisms that are produced so there was a struggle for existence not every peppered moth could get into a place where it would find out so there was a
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struggle for existence now in this struggle for existence there was survival of the fittest so in the presence of predation in the sort of an environment this one survived better so this would be said survival of this organism was was preferred by
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natural selection in this environment this one was preferred so there was a survival of the fittest and this also resulted in two changes in the gene pool now here it is important to note that whenever there are these changes in the
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gene pool in most of the situations we do not have a situation in which you have 100% organisms that are of one variety and no organism that is there of the second variety so coming back to the drawing board here we observe that even
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in the first situation we had a very few number of individuals that were dark in color but they still remained there in the system variation is very crucial for the system to survive because if it so happened that this number went to zero so there would not have been any more
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variation that was remaining in the system and once the system changed once it moved to a polluted scenario if we in this situation if you only had the light colored moths so in this situation all of those light colored moths would have
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been eaten up so no peppered moths would have existed today whereas nature always prefers to have these variations and so even in these situations we observe that we will have some number of individuals that still
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persist in the system even though they are not the best suited now how does this selection occur we have three different kinds of selections which are called as directional selections stabilizing selection and disruptive
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selection now in this example what we are observing is that here we have the frequency of individuals and here we have different colors that are present in the population so here we have an organism that is very light in color here we have an organism that is very dark in color and these are variations
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in between now suppose the original population was something like this so it the most preferred or the most fit organism was there in the center now in the case of a directional selection this curve would shift either to the right or to the left so what we
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are saying here is that here we have the frequencies of individuals and here we have the color let us call these shades
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as 1 2 3 4 & 5 and the earlier population was something like this so in this case we had most of the organisms that had this color of 3 so this is the most preferred one now if the situation
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changes and if the if this curve shifts to the right so it becomes something like this so in this case we'll have that this all the organisms of shade for
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are more selected so this is a directional shift so essentially the peak of the curve shifts from this to this or it can move to the other side as well so this is a directional selection the second selection is called a disruptive
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selection now in the case of a disruptive selection we have a situation in which these organisms are selected the middle ones are not selected and then the larger ones are selected
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so in this situation we have that the light ones are preferred and the dark ones are preferred but the middle ones are not preferred now when do we have a
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situation like this so suppose you have a forest in which you have some trees that are dark in color
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and then you also have some trees that are light in color now in such a forest if the light colored individual goes and sits on the light colored bark and the dark colored individual goes and sits on the light colored bar both of these are spayed from predation but the middle color whether it goes to
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the dark tree or whether it goes to the light tree it is not that much camouflaged so it becomes apparent and it gets predated upon so such a selection in which nature prefers the two extremes but not things in the
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middle goes by the name of or disruptive selection and third is a stabilizing selection so in the case of a stabilizing selection we have a situation in which earlier the curve was
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like this the other curve was like this in the later generation this curve becomes even more narrow down so for instance earlier
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we had these shades 1 2 3 4 & 5 in generation 1 but in the second generation the shades 1 and 5 get completely removed and now this whole curve has become even more towards the
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center so in this case we have lost two traits and we have even shifted the system towards a center point so this would be called a stabilizing solution and we observe examples of all three of these in the nature so for instance this
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is a study of directional selection so there is a set of islands that go by the name of kenapa goes Islands and here we have birds that have all finches now these birds have beaks and their beak size was studied now there was a draught
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in 1977 and before the draught we had this sort of a curve so what we observe here is that this big depth of 8.8 is the most preferred one now after the dot what happened was that
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during this period most of the nuts that were there became even more harder to break open so here we have this chart of seed hardness versus the big depth now if you have a seed that is harder to
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break open so you require a larger sized beak to break open that seed now in this draught what we observed was that before the draught we had this pattern in which the beak size of 8.8 was more preferred after the the draught it shifted from
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eight point eight to nine point eight so there was a directional shift towards larger sized beaks because of the draught so this is an example of directional selection an example of stabilizing selection is the the weight of human baby head birth so here we'll
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observe that if the weight is around eight pounds so we have minimum amount of mortality that is there in the six in the system and highest amount of survival rate if it shifts to the right or to the left so in those situations these babies die off more easily now
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this is obviously a very old paper and our advances in medicine have enabled other babies to survive today but then if you look at this graph if you only concentrate on this graph will observe that babies of eight pound are selected
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so this is the most optimum weight this is an example of a stabilizing selection so if you shift to the right or to the left you have a lesser probability of survival now this is an example of a disruptive selection so this is again an example from Galapagos Islands in which
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we had a bird population in which these beak sizes were more preferred and then this big size was more preferred but the center ones were were less preferred now why can nobody have a situation like that we can have a situation like this if to have an environment in which you
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have say these nuts that are hard to crack in these nuts that are easy to crack but you do not have any nuts that come in between so if you have a that comes here it won't be able to crack a larger sized or a more harder
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nut but if it tries to crack open these softer nuts so it'll face a lot of competition from their already existing birds which have smaller big sizes are and are probably more adapt or a more amenable to crack
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open those softer nuts so in such a situation we'll have a disruptive selection so we'll observe - so next we have a look at coevolution which is a situation in which there are two species that are evolving at the same time so
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this is the evolution of two or more species that interact closely with one another with each species adapting to changes in the other and a good example is bee hummingbird that is feeding on these flowers now in these flowers they have
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an elongated shape much like a funnel and there is nectar on the inside and the Frog produces nectar to attract these birds so that if this is a flower and here we have the nectar this bird
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reaches and tries to feed on the nectar and in that process it gets the pollens from the flower onto its beak and it when it goes to another flower of the
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same species it is able to transport these pollens from one flower to another flower now if this bird randomly fed on different flowers so it went to say this flower that belonged to species one and then it went to another flood that
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belonged to species two so in that case the pollen grains of a species one would be transmitted to species 2 which would not make any sense because these pollens will not be able to result in fruits in the case of the second flower so nature
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wants to have a situation in which the birds and the flowers are specific so essentially if you have a bird species that is that has this beak it should only go and feed on flower so office species one and the birds that
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go and feed on flowers of species - should be different so species one birds should not be able to get to species two flowers and species two birds should not be able to get to species one flowers so essentially we have this situation in which you have say this is your species
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from one and this is your species - now in the case of species one you have a flower that has the shape and in the case of species two you have a flower that is more elongated now in this case
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a shorter beep would do in this case you will require a very long beak long and slender weak to get to the nectar now consider two individuals of a species -
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so one is this individual and then there is another individual that has an even more elongated flower so this is another individual of the same species species - now if we consider a bird such as this
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bird and let us consider one more variety which is this one now in in such a situation if we consider this bird it will not be able to feed on this flower
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it will not be able to feed on this flower but it might probably feed on this flower whereas this bird would be able to feed on so let us consider this bird it will be able to feed here here here and here
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as well but in this case it will find it more difficult because it is facing competition from this second mode which has a shorter beak now in such a scenario we'll observe that if this is
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species 2 has these different individuals this individual with the longest tube or the or the the long funnel will be much more specific as compared to this individual that has a
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shorter finale so if you want more specificity more specific a more specificity would mean that you have more probability of reproduction because more probability of pollens from the same species reaching into the flower of
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the same species so you want to have more amount of specificity now more specificity is being provided by a longer funnel and not by a shorter funnel so after a while because natural selection is selecting those organisms
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that are best suited or that are the most fit and in this case we are we can intuitively guess that a longer funnel will result in more amount of of a specificity and so more amount of fitness so a longer funnel will be
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preferred and when that happens this bird will also have to evolve because in the next generation if you have even longer funnels so you also require an even longer beak to get to that nectar in that particular flower so this bird
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will also have to evolve at the same time so the evolution of one species is driving the evolution of the second species and now if this bird evolves what will happen is that these individuals of the same species that were having a smaller size or or or a
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shorter funnel they will be they'll become even less fit because now this bird will choose to get into a larger flower a longer flower as compared to a smaller flower and this smaller flower will we'll maybe start getting Birds of
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some other species so in this situation the longer beak of the bird will also result in more amount of evolution in the flowers so this is an example of coevolution another example of
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coevolution is the evolution of horns now in a number of herbivores we observe these horns so this is an example of a cape buffalo and the horns serve as a deterrent from the Predators so if there is a lion and if this line
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observes to Cape Buffalo's there is one Kaiba fellow with a long horn and there is another cape buffalo which does not have a horn say it's a calf so approaching a calf is much more easier as compared to approaching an adult with
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long horns because if this elk tries to fight back with its horns it might even be able to kill the line now if you have a situation in which you have Hans so in that situation the predator will also
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have to evolve some strategy to be able to counter a counter vent these Hans so probably the predator will start approaching the adults from the behind so evolution of horns which was a risk a
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response to the pressure of the Predators would also result in evolution of some other behaviors that are there in the predator another example is evolution of the stripes of zebras now why do zebras have stripes now zebras have stripes so that if there
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is a group of animals and all of these animals are having stripes and then there is a line there is a predator that
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is chasing say this particular zebra if this zebra moves into the group then the line gets confused which zebra was the one that I was chasing now if you have only one zebra which the line is chasing so the line will be very easily able to
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capture this zebra because after a while our zebra will also become tired but if it gets into this group and probably in place in the confusion the line in place of chain in this zebra now shifts its
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attention to another zebra so in this case this zebra will be able to get its breath back and will be able to survive so this is one mechanism that is Abra's in evolved to are to be able to
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circumvent the Predators so here again we see an example of coevolution because we had predators so we had this evolution of the stripes or for instance why do impalas run fast well impalas are run fast because they have to counteract the Cheetahs so here
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we have the impalas here we have the Cheetahs and if these impalas are not able to run fast then these cheetahs will be able to predate on these impalas but then why do cheetahs run fast cheetahs are run fast because they have
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to predate upon the impalas which run fast so essentially these two species because they are interacting so closely with each other they are evolving at the same time so this these are examples of coevolution so what we are observing
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here is that if you have two or more species that interact closely with each other so in those situations the evolution of one species leads to the evolution of the other species and the evolution of any species becomes
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dependent on all the evolutions that are happening in all the other species so they all become linked together now why are these organisms interacting with each other and interacting so closely with each other and that's because of ecology in the case of ecology we saw
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that we have situations of population ecology a population ecology would say that in this group what are the interactions between these different animals if this animal is slow and others are fast then this would be eaten up and its genes would be removed from
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the system so interactions within the population are important similarly interactions between the species are important so here we are talking about community ecology so we have ketta then we have the impalas what are their interactions so ecology becomes very important for
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evolution because the ecological interactions drive the evolution of different species and which is the one of the importance of learning the subject of ecology that we can understand evolution how it happens why
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it happens if we are able to understand the interactions that are happening within a species between the species and between the environment and the species the environments are changing so in this lecture we saw how ecological
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interactions are driving evolution we began with evolution what is evolution how it happens what is what are adaptations what I our genetic adaptations and what are the steps of evolution how does natural selection act
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what are variations why do we have overpopulation why do we have a struggle for resources how does survival of the fittest happen and how does that lead to evolution and then we moved on to the process of coevolution where different species are
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interacting with each other and driving each other's evolution not only the species interact with themselves but they also interact with the environment so any changes in the environment also Drive evolution so all of these in total can be said that ecological interactions
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are driving movie which is a very important reason to understand wildlife ecology so that's all for today thank you for your attention [Music]
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