a big hello to all my wonderful case aspirants I hope you're doing really really great my dear children And today we are going to do one short video for organisms and population and it is going to be really really fun I know that exam is nearing You might be bit worried about things but please be rest assured that you don't have to worry about things You have to work on things and if you're doing so you are going to do crazy good Okay So let's begin One shot So I want your NCERTT uh and also a pen if at all I say that this is something important you can write it down as in everything is important but then some things know you might feel that oho it's not just that important it's just okay it's just there I just have to read it once no you might have to read it twice and I would be telling you those things and also when you have your NCERT with you while I'm teaching you one shot it gives you an idea where am I teaching from okay this this portion is completed okay I'm feeling a bit confident okay so I think we are ready let's start with the first initial paragraphs that we have in the chapter Okay So in that the definition of population is given after the little introduction I'm talking about the next part which is there in that definition of population is given What do you mean by population it's just a group of individuals like us who are of the same species who are there in a specific area my dear children So we say that we are a population of human beings Yeah So they are going to utilize the resources They're also going to potentially interbreed among themselves Now cornins in a wetland lotuses which are there in a pond Okay bacteria which are there in a culture plate all of them is example of population This is population of bacteria This is population of flotus This is population of corans which are there Now exactly what is written in the entirety I just I'm just telling you those examples Now if you compare population with individual for example jasmine ma'am is separate thing and human being population is separate thing So in individuals my dear children individual will experience birth and death Either I can die or I can get born So there is birth and death But when you talk about population there is birth rate and death rate My dear children you you basically calculate it like this So if eight new lotus plants grow in a pond with 20 existing ones So there was a pond my children and there were 20 lotus plants Eight eight of them they grew Now so what is the birth rate over here so we do 8 by 20 which will be 0.4 per lotus per year So there's a time period that we allocate a specific area We're going to calculate that Now there is death rate as well So number of individuals dying in a population per unit time Okay per unit time So how do you calculate it number of deaths which is there upon the total population size So if four fruit flies are dying in a population of 40 what do you do four divided by 40 is equals to what 0.1 per fruitly per week This is what the death rate So population we use birth rate and death rate For individuals we say birth and death only Now apart from that in population we have one more thing that is sex ratio So what does it what do you mean by sex ratio it is just a proportion of males and the females in a population For example I say 60% of them are females and rest 40% will be what males So this gives an idea about how many organisms belonging to one particular sex are there in one particular population works So these are small small attributes that are there in the population I agree the initial part of the chapter is little bit boring but obviously it is important We have to study Now this particular thing that I'm showing you over here is highly important because you get questions every year on the basis of this So age distribution and age pyramid first of all what do you mean by that so population consists of individuals of different ages Don't you agree I'm of different age you are of different age even though I want to be of your age still I am of different age Then some might there might be someone who is more age than me There might be someone who is what say very younger than you You get it so these are the age different ages that we have Now what does age pyramid mean age pyramid shows the age distribution in a population It shows what age distribution in a population So pyramid shape indicates the population growth For example there are three pyramid shape One is expanding the other one is stable and the third one is declining How do I say it's expanding basically the lower bar which is there it indicates the organisms belonging to pre-productive age as in they have not reproducing now They are in the pre-productive age but they will be growing They will be growing they will get matured they will reproduce so if I see that these organisms are more in numbers so obviously I'm sure in future they are going to increase the population they are going to increase the population so here reproductive is less and post reproductive is way lesser than that so if prerective if my future is secure over here if they are going to reproduce my DN I'll say it's expanding type of population now on the other hand if I see the pre-productive and reproductive is almost almost same my dear children it's almost uniform shape that I'm getting over here So I'll say it's a stable it's a stable thing Okay people are there people will reproduce but it's not going overboard Now over here if I see the pre-productive age group is way too less That means in future I would not be seeing so many children out there So obviously the population size is going to go down So I'll call this as declining population growth So with the help of different age pyramids I'm getting to understand what is there about the population growth So is it increasing is it stable is it declining everything So expanding in that you will have a broad base and obviously this indicates there will be high birth rate There's high birth rate which is why it is happening Now stable as in there is a uniform shape and there is equal birth rate as well as death rate my dear children So over here birth rate is very high but death rate is what say death rate is also high but birth rate is also even more higher which is why it is given up over here Now narrow base means low birth rate is there Narrow base means low birth rate there So forget about birth rate over here At least you understand the pre-reproductive age groups If it's way too much expanding if it is same stable if it is less it is declining Okay So we studied about population What do you mean by population we spoke about the birth rate death rate and we also spoke about what the age pyramids which are there Now are there certain factors which affects the population size do you think so so population size is dynamic that is it changes over time due to food availability predation and weather So is the population size the same as it was 20 years back no my dear children because now the food is a limiting resource my dear children what will happen there are people or in the future probably we might just fight for food Okay we might just fight for food and since the food availability is really less and the population size will go less So it changes changes over time because of certain factors like food availability predation okay and also the weather Now fluctuations indicate whether a population is growing or declining Okay fine Now there are four basic processes that are affecting the population density and you have to remember it What are the four bas four basic things natality mortality immigration and immigration Natality means birth rate Number of births in a given period If natality is more if the people are getting more more so obviously the population size is increasing If mortality mortality means death rate Number of death in a given period That is what you mean by mortality Death rate Please make sure you're talking about a given period Okay There's a specific time period Now over here if mortality is more people are dying more Do you think population is increasing no The population is what decreasing What about immigration immigration means for example this is a place lot of people are coming over here So don't you think here when they're coming inside over here the population is going to increase over here Yes So individuals entering the habitat from elsewhere This is a mis immigration Now immigration E for exit my dear children So people are living For example you guys came in my room and now you're living here So population size my dear children it will go decreased So there are two factors which are going to increase the population that population density that is nality and immigration There are two factors that is going to decrease the population density that is mortality and immigration Okay please remember e for exit Now population density formula So if n is the population children n is what the population density at time t then the density at t + 1 is So after some time what will be the density so how do we calculate it this is the present day population density that we have Okay this is the present day population density Plus what we are going to do plus we are going to include the birth rate as well as immigration That means natality as plus as immigration minus death rate plus immigration When you do that okay when you do that suppose over here the birth and the immigration is way too much If birth and the immigration is way too much than death and immigration that means population is going to increase ar people are reproducing more Okay Basically reproduction rate is very much and people are getting uh coming to our particular place obviously population size is going to increase But on the other hand if this is more if death rate and immigration is more okay people are dying and whatever people are there they are going off also then that means population is what decreasing my dear children So this is the formula for population density after time t okay t plus one time t plus one So please remember this formula as well Now influencing factors that is birth and death are the main factors under normal condition You also talk about immigration and immigration as crucial things when you talk about colonization to a new habitat for example from organisms when they're coming from different places and settling over here or going to different location at that point of time even immigration and immigration plays a very very major role works I hope you're understanding are you okay so please remember these are the four basic factors that affects the density population density very very very important and this is the formula that is also very very important Now going ahead exponential growth model and there are two growth models Okay the population of growth if you talk about that there are two models So exponentially growth means for example there is nothing that is limiting my dear children nothing that is limiting food is there water is there everything is there So if everything is there what will happen the organisms keep on growing they will what keep on growing right so if they keep on growing will the graph if this is a time if this is a population density the graph will go shoot up like this will it stop anywhere will it come down anywhere no it is going to increase what do you mean by this basically that means population density is keeping on increasing this is exponential curve my dear children and it is giving rise to a J-shaped curve if you see initially obviously it will take some time to pick up but after it picks up it is just shoots up so this is J-shaped curve that you get when exponential growth is there okay and when do we say exponential growth is there when the resources are unlimited population grows exponentially Here the population follows J-shaped curve Okay So how do you explain it so growth rate is defined by dn by dt dn by dt is equals to b minus d n What does b stand for birth rate What does d stand for death rate What is this basically population growth after some time Okay this is what population growth after some time my dear children And this is the present day population So B minus D when you find it out okay suppose B is more obviously then the population density also growth will also be more if D is more then that means what's a population growth is not that great okay so over here B and D is represented by R my dear children okay B and D it is represented by R it is known as intrinsic rate of natural increase it is what intrinsic rate of natural increase okay now there's an integral formula for the same thing that is NT is equals to N E R T NT is equals to N E R T All these formulas are really really important Please know what does everything stand for This is intrinsic rate of natural increase B is birth rate D is death rate This is present day population size And this is after some time Okay Here NT stands for population size after T N stands for initial population size which is there R stands for intrinsic growth rate and E basically is a natural logathic base that is being used is 2.718 So examples of R value R value is different for different different organism For example for Norway right it is 0.015 Okay Norway right it is 0.015 So in a particular area my de children over there the birth rate is in more than that which is whatever is there it is 0.015 015 for flower beetle it is 0.12 India's human population in 1981 was 0.0205 0205 So depending on it it changes It fluctuates always Okay Now even slow growing species like elephants can reach huge numbers under unchecked exponential growth Yes even slow growing organisms like elephant m their growth is really really slow But they also can show exponential growth if the factors are not limiting Always remember if you're given this question okay that uh basically you are growing bacteria in a culture medium and you are providing what say all the resources what type of growth does it show if you're providing all the resources every now and then my dear children are they going to have limitation of any resources no so what type of growth they're going to show they're going to show exponential growth and this is a J-shaped curve please remember this formula very very very very important okay this is time this This population density works and this is a logarithmic formula Now integral formula now we have okay so this is not exponential growth This is logistic growth Now we have logistic growth model which gives you a sshaped curve and you might be thinking why S-shaped curve ma'am So basically initially it will also take time to pick up Slowly it picks up but then it realizes that there are limiting resources this particular area cannot hold more than these particular organisms Now this limit that you see is known as carrying capacity This is known as what carrying capacity So over here whenever you're calculating the population size you have to include the carrying capacity as well Okay So in logistic growth model and over here if you see it's a Sshaped curve even though not exactly S but there's an S shaped curve over here So in nature my dear in actual sense if you talk about actual sense in nature resources are limited So exponential growth cannot continue indefinitely right as the system becomes scarce competition increases and only one of the fittest will survive and reproduce You know that as well So the maximum potent population size that an environment can support is called the carrying capacity The maximum population size an environment can support is the carrying capacity after beyond which it cannot go there's a maximum population size a plot of n in relation to time results in sigmoid curve now s means sigmoid okay this type of population growth is known as world's pearl logistic growth please remember world pearls logistic growth this is known as worldsp logistic growth there are different phases in this logistic growth one is lag phase where slowly growing slow initial growth then there is acceleration phase m where there is rapid increase in the population then there is deaceleration phase race it will slowly slow down that growth slows as resources become what limited and then asymtote that is population reaches a carrying capacity beyond which it is just stable it is not going to increase not going to decrease nothing so these are the different phases which are there in logistic growth please remember it lag phase then acceleration phase then deacelation phase where the growth actually slows down and then as where there's a stable thing it has reached the carrying capacity it the growth is stabilized over there and what is The formula for this as I told you dn by dt is the population size after some time r is intrinsic rate of natural increase N is the population size as of now Over here k stands for carrying capacity K minus n divided by k is a thing that is there So this is a carrying whatever in the carrying capacity How much amount of population size has it already reached This gives you an idea about that Cool This is how you calculate this So please remember this formula very much important also sshaped curve which is there Okay This is J-shaped curve which is there in exponential growth not in logistic growth works So children there is no point of teaching slowly also why because you will get bored right you will get bored and also in this way you are challenging your brain to understand things in a faster way and I'll tell you you have already studied this in your board examination or probably your preparatory examination and things like that So I want you to basically uh take up this time and utilize it properly Which is why if at all I am in a bit if at all I am speeding up it's because of that I want you to understand that I don't want you to have a long lengthy lecture and get bored and not study anything But I hope but I hope you're understanding things If at all you think that no I'm not able to match this pace what you can do is there's a option to slow down the video as well slow it down a little bit and see if you're able to understand or not Okay and for your doubts children I am here You can put down that in the comment section I will be clearing all of your doubts So be rest assured for that And as I said I don't want to waste any bit of your time So let's get ahead Okay Now there is reproductive fitness and strategies It's a small thing given in your NCT You might not have even seen it Okay So let's see So it is reproductive fitness is also known as Darwinian fitness So high R value means reproductive success So R values is something that will uh make you understand about the reproductive fitness It is it is it is denoted by R Now organisms adapt to maximize reproductive efficiency based on the selection pressures Now type of reproductive strategies there are organisms that breeds only once once in their entire lifetime Example Pacific salmon and bamboo They are known as simil paris organism Now similar paris term is not given in your NCR Okay The single time breeders you don't have to remember it If you want to remember it you can So the single time breeders breeds only once in their lifetime Example is specific salmon and bamboo Now multiple time breeders they known as iteroparis organism They breed many times in life Examples birds and also what mammals might eat like us Okay Now offspring production strategies There are strategies where they produce many small offspring Why because they want to make sure make sure at least a few of them could survive You might have seen puppies Okay there are so many being produced but then there at the end there will be one or two So at over here there are high quantities there the quantity is really high but low survival rate is there which is why which is why they have so many kids example oysters and pelagic fish that is something that is extra and then there is one more strategy where there are few large offsprings So over here for example in the case of human beings there are not 10,000 children only one or two children why low quantity but there are high survival rate my dear children which is why there is no need of producing so many organisms so birds and mammals comes under this so go through it once is not very much important it's just there we never know questions can come yeah okay so let's go ahead over here my dear children we have population interactions which is the most important part of this particular chapter So you know in the population the different organisms are going to have different different types of interactions which are being mentioned over here So mutualism is a type of interaction where basically both the organisms which are participating are getting benefit So this is the best one Then we have competition where one organism and the other organism species A and species Basically two organisms both of them are not going to get any benefit of it So it will be minus minus since they are not getting any benefit both of them it for both of them it will be detrimental it is bad okay if you talk about predation for example tiger and a deer tiger eats the deer so for tiger it got its food so it will be plus but for the deer it died so it will be minus talking about paracetism which is again like predation itself so it will be plus and then minus for example a tick on the body of the dog it is continuously feeding on the blood but is the dog getting benefited No there's a negative effect that has been shown even though it's very little but still So it is minus and plus over here Commensalism is basically when an organism is getting benefit and the other organism which is participating is not getting the benefit nor is it harmed Okay that is commensalism Now amensilism is given in your NCERT textbook So over here amensilism is explained in this manner Apart from that in your NC textbook there is no explanation of amensilism My dear children immensilism is when one organism is getting harmed and the other organism is basically not going to get any benefit or it is basically unharmed as well Okay So one organism definitely it is harmed other organism is neither benefited nor it is harmed So predation parasitism and commensalism my what predation parasitism and commensalism three of them share a common character and what is that the interacting species live closely together They have to live closely together Then only they can show these interactions And this is a really important point This point that you see is a really important point Okay Predation parasitism and commensalism They h have to make sure that the interacted species are basically closely living together Cool Now going ahead we have examples of predition and the uses of predition So what is the use of predation basically for energy transfer it is very much important Predators help transfer energy from auto drops to higher trophic levels So for example there's a auto drop that is a plant Now plant is been eaten up by what uh the grass sorry plant is been eaten up by the rabbit So rabbit is a predator right so whatever energy is there in the plant my dear children isn't isn't the rabbit having it now whatever organism is going to eat the rabbit Suppose the tiger is going to eat the rabbit Now this particular energy is going to get transferred to the next trophic level So obviously they are going to act like a condute Okay What do you call this term as you call this term as condute They are going to act as condute or connecting link between energy transfer Okay The second thing predator maintain the prey population That is if a predator overexploits prey Both the predator and the prey they may become extinct For example there is tiger and it eats on all the deer which is there Now what will eat on what will it survive on both of them If there is no food both of them are going to die So make sure there is one very important thing that you have to remember Natural predators are prudent to avoid this Basically they have that mind Yes I cannot do that I cannot do that because if I if I'm a tiger if I eat all the d what's a deer I would not have the food later on So they are very much prudent my dear children So they are condued because they help as a connecting link between energy transfer They are prudent because they make sure that they are not overexploiting the prey population because at the end they might only suffer because of the same thing Works got it Now there is exotic species and predation So invasive species spread quickly due to absence of natural predators Now what is the use of having predators one use is basically you know what you know invasive species as in some organism which we get from outside It is not indigenous indigenous as in for example organism which are already there So invasive species can come over here and they can basically uh what's it say take up the whole thing if there are no natural predators If there are predators what will happen predator will eat them up and these invasive species would not be spreading So example is prickly pure cactus in Australia It was controlled by a cactus feeding m Okay So prickly pure cactus it was an invasive species which was there Okay This was a invasive species which are there in the a in Australia But then you had cactus feeding moth which basically feeded on this and made sure and made sure that it is not spreading really quick because if the invasive species spread really quick medium what will happen they will use all the resources and everything and it will be a big problem for the indigenous species of organisms which are there Okay So this is one very important use of predation Okay Second thing it is going to act like a biological control So you might have seen in pest control Okay We studied in biotechnology and its application and also microbes and in human welfare that basically there are certain organisms which are going to feed on pest Now if it is going to feed on pest obviously we we can be made sure that the plants and all are safe because there is someone to eat So this here predator is really important because it is acting as a biological control agent Okay Now it helps in maintaining the species diversity How basically if predators reduce competition among the prey species So prey species also if they are way too much in number For example human beings Not human beings for example deer itself If they are way too much in number all of them will need grass to eat the food They will need grass right so they will if their number is increasing they will be fighting among themselves There will be competition happening among themselves my dear children and that is very big problem So what do we do if we have a predator over there if we have predator over there it will control the prey population so that the prey population is not weigh too much Hence it can be feed it can feed on the available resources which are there So starfish removal led to extinction of several species of the American Pacific coast So what were happening there was a starfish that is known as pisaster of my dear children which was a very important predator It was a very important predator Now when this predator was removed it was noticed that there are several species of American that were there in the American Pacific coast that got extinct because they they fought among themselves There was there was no resources left for them to have food because there was so many in number You get it so predators basically help reduce competition How did they understand by removing a predator that was pisaster starfish So here they had two examples All these examples are really really important You might be asked you might be asked what type of relationship does they show So prickly peer cactus Okay which was there it was a prey What was a predator cactus feeding moth It was a good predator because this was a invasive species and we did not want this to spread in Australia Now talking about biological control you have lot of things for example bass stringenesis Okay which is a bacteria It feeds on the pest that is butterfly caterpillars and everything and make it under control Now there is one more thing that is starfish Over here predators are helping in reducing the competition among the prey species So when this pisaster starfish was removed what happened in the American Pacific coast there are several species that got extinct Okay So I hope this is clear Okay Now going ahead there are few more things that is prey defenses against predators So until now we were talking about the use of predators predators and everything but prey also have to make sure that they are safe They also have to make sure that they are safe and they definitely have defensive mechanism for that For example camouflage So there are there is cryptic coloration in insects and frogs my dear children And for example if I wear blue dress and come paint my uh what say face in blue and I stand over here you would not be able to see me even though you would be able to see me but in generally I'm talking in general I'm talking basically I'm I'm camouflaging and with the help of that I am defending myself I I am basically safe from all the predators who are looking for me Now there is there are poisonous species of organisms as well Now example monarch butterfly stores toxins from the poisonous plants So you know monarch butterfly is there It is highly distasteful my dear children It is what highly distasteful Does not taste good at all So how why is the what is the reason behind it basically in its larger stage at that particular point of time it feeds on a plant that releases toxins Okay So these toxins are there stored in their body So whenever they grow up basically any organism that comes and eats it it will be feeding on the toxins which are stored over there So these are poisonous species Obviously no no one would prefer having it So these are the two things that is there for animals My dear children examples of animals One is camouflaging and other one is just having poisonous species Monarch butterfly is really really important Now herpivore in in the case of herbivores also okay the plants also plants if they are the prey they also have to do some defense mechanism right so in plants there are few as morphological defense for example thorns you might morphological as in if they're if they're making some changes in the structure and that is helping in their defense this is known as morphological defense for example they have thorns and all so any organism which comes to eat it oh my god my tongue is paining so basically it's because of thorns example you have acacia and you have cactus You might have seen in cactus you have thorns right now Apart from that there are chemical defenses that is it produces toxins to harm herbivores Basic example is calatropus Now calatropus it contains toxic guardia glycosytes which are avoided by cattle my dear children And I'm pretty sure I forgot to put the picture over here of calatropus but I'm pretty sure you might have seen it any time in your life So you can just Google it and see it once It gives you a sense that oh this is a plant that pal is talking about and you might remember this for a longer time So calatropus it contains toxic cardiac glycoides migration So that is why it is prevented eaten by sorry avoided by cattle Okay Now commercially important plant chemicals are also there So nicotin caffeine quenin and spctin opium all of them they are actually was they were evolved as plant defenses but now has been commercially used as well Okay So in predate in in the prey species defense mechanism two are there for animals that is camouflaging and poisonous species such as monarch butterfly In the case of plants my dear children please remember there is morphological difference that is thorns in the cactus and chemical difference that is seen in calotropies where they store what say toxic cardiac glycosytes which is going to what say affect the cles who feed on them Apart from that there are commercially important plant chemicals such as nicotine and caffeine and all this thing which are mentioned over here They were actually what say originally they were plant defense mechanism but we are utilizing it for our own purpose So 25% of insects are phytofagus What do you mean by phytofagus plant eating So we have to make sure that we plants are safe from the predator that is what the insects that is all about predation Please I want you to remember as I said predation that means one is getting uh periphit the other one is getting harmed So it is a plus minus relation So over here two of them has a plus minus relation that is predation and parasitism Okay now we are going ahead What about competition my dear children competition both of none of them are going to get any benefit of it So let's see what is competition Before that we have case sit series as well as crash course thingy So my dear children I hope you're already aware Just give me a second Okay Okay I hope you're already aware about the test series and the crash course If you're not let me tell you So there is a completely online test series which is there There are 35 full syllabus and chapter wise test which is there There is video solution for all the problems that we are going to give you There will be one short revision videos and also last five year paper analysis Okay you get it so it is you're going to get this in rupees 1499 Okay Now as I said it's completely online Now talking about case crash course here there's a 21-day crash course which is happening at our campuses There is Dsha campuses and it will be taught by the teachers who have a legacy of bringing outward ranks So here also the test papers are set by the same teachers So you not have to be worried about where's the test paper coming from and all Okay But here it's like a crash course So obviously you would be learning a bit more It's not just a test series and it's a 21-day course It's there in Bangalore So if you're someone who is there in Bangalore you can come and attend If you're not there if you're not from Bangalore uh we provide the hostel facility as well else we can come stay and learn as well If you have any questions regarding this please call onto this particular number or else you can go ahead click on the link in the description box You will get more idea about both these things But make sure you're taking an informed decision Okay Now let's talk about competition I told you competition means none of the organism are going to get benefit They're going to fight which is why we say that we should not be fighting with each each other Okay So there are few things that you should be knowing I think we should be going with this particular slide first So competition as I said both of them are getting harmed So according to Darwin's view he said that intpaccific competition is a major force in evolution What do you mean by intpaccific between different species the competition which is there it is going to act like a major force of evolution The one that survive will be evolving better You get it one that does not goes off So there is it is not rem related to please remember please remember the competition which is there it is not just related to related species sorry it's not limited to related species unrelated species can also compete so it is s that human being human being fighting for the same resources that is we are related species so competition is not just limited to this but it can happen between unrelated species as well how ma'am basically you know flamingos that's a bird and fishes Both of them they are going to fight for zoo plantin Both of them they're going to fight for zoo plantin And what is this type of competition this is interference competition Why basically what happens is that because flamingos are there fishes won't be able to eat food properly or because fishes are there flamingos would not be able to have the food properly So just because of the presence of one species it reduces another's efficiency even if resources are abundant by nature At this point also it definitely happens So this is known as interference competition which is shown by flamingos as well as fishes competing for zoo planktons So over there there are two different species unrelated species still competition is happening over there and relive competition major force of evolution This was said by Darwin Now let's talk about evidences of competition in the nature So you know competitive exclusion what do you mean by that so if resources are limited my dear children a superior species eliminates the weaker one This is what you mean by competitive exclusion And it does not just came from like that okay from the sky Basically there was a person who studied about that that is Goss So Goss put down his competitive exclusion principle according to which he said that two species okay remember two species cannot coexist indefinitely if they are competing for the limited resource If both you and me are competing for one dosa which is calculated over here We both cannot coexist together We may not we cannot coexist together indefinitely my dear children However recent studies suggest competition often leads to coexistence strategies But now it is said that they can lead to coexistent strategies as well But initially Goss's competitive exclusion principle said that two species cannot coexist indefinitely Why one species will be competing with the other because there is a limited resource that is there Okay this is what you mean by competitive exclusion I'm going to talk about that then I'll tell the other scenario that is coexistence is also prop is also uh u what say is also possible so I told you one dosa between you and me okay either is that I take it I have it completely that means we cannot coexist okay that means you have to basically exclude go out of this so if resources are limited a superior specy eliminates the weaker one example abnant tortoise extinction due to introduced goats so you know what happened goat Goat and tortoise both were there Okay So initially tortoise was there and tortoise was feeding on the grass which was there Then the goats were introduced but goats were kind of dominant Okay They could eat faster and they could was say reproduce faster So they were the superior species And after one point of time what happened the abden tortoise they became extinct They became extinct So isn't it an example of competitive exclusion yes Isn't what God said is correct yes According to this example it is completely correct Now there is one more thing that is competitive release There's another term okay but before coming to that I have to come to the other scenario I told you either they can go off according to Goss' competitive exclusion principle they cannot coexist indefinitely They are going to compete for the same resources and that's all Okay So this is a perfect example of that Now there's another scenario where basically what I do is that I the dosa which is there we both divide it equally and eat This is known as resource partitioning In that way we can coexist in the nature and that is also seen So resource partitioning is the alternate thing of this where species divide resources to avoid direct competition Okay we do not want to have a competition which is why we do resource partitioning Example macarthur's wobblers foraging at different times location in the same tree So there were five different species of wablers my dear children and all of them they could survive they could survive on the same tree Why because their foraging time was different The area which for example some of the organisms were eating from the down some were eating from the upward some were coming morning some were coming afternoon In that way they were able to what coexist Okay And this process is known as resource partitioning which is completely opposite to what go said Go said it is not possible but here people are showing not people organisms are showing what coexistence strategy as well but make sure they are doing resource partitioning Okay Example is wobblers Example is macarthurus wobblers There are five of them All of them could survive Okay five different groups they could survive Now there is something that is known as competitive release What do you mean by that a species expands its range when a competitor is removed When a competitor is removed what will happen say for example Bellanus was there Okay there was a barnuckle that is Bellanus and there was another barn knuckle that isalamus We call it thealamus only Thalamus was smaller ones and Bellanus was the bigger superior ones So they were living in the same area but then but then the in superior one it said that you cannot live you go away So it excluded the phalamus were excluded from the zone intertital zone Okay from the intertital zone they were completely excluded So the larger and completely superior bernuckle dominated the intercidal area and excluded the smaller buckle from that particular zone So over here when both of them were here together and now when one is going don't you think the other one is going to take the whole space this is known as competitive release A species will expand its rage when the competitor is what removed Cool Now this is a result of this It is a result of competitive exclusion It is a result of competitive exclusion Either you got extent either you go extend otherwise Yeah whenever you go extend basically I get the whole area so this is the result of this got it so first we learn causes competition extension principle which say that two species cannot coexist indefinitely if they're competing for the same resources example is basically abandoned to their extinction was seen because the goats were introduced over there the goats were superior they excluded the other guys now when the other guys were excluded what happened the goats got enough area to have food and everything same thing was seen in an experiment that was done by corners so remember this name is really important Connell's elegant field experiment included what so you should know it was it was a bernakle that is balanis and another bernakle that is what thalmus So bernakle balanis was able to dominate because it was a superior species It dominated the intertital regions whereas the other ones were removed from that particular zone Now the opposite of what gosh's principle says is coexistence So organism nowadays have evolved out coexistence strategies by resource partitioning This is shown by wobblers of Makatu's experiment Okay Done So that's all about competition Okay Now parasism Why okay First why are these statements important they can give you to find the incorrect statement So you might if you're not knowing what is incorrect statement you might lose your marks Which is why I'm telling you this very prominently Okay Now the next one is parasitism Parasitism also one gets benefit Okay one get benefit Anna gets harmed Right so it's a relationship with the parasite benefits at the expense of the host So host specific evolution my dear children So parasites and host which are there co-evolved The host resist and the parasite basically adapts That is what we have seen So there are special adaptation in parasites that we should definitely know Okay Again a question can come which on them which among them is not a special adaptation So loss of unnecessary sense organs this is an adaptation Presence of suckers and adhesive organs because they have to stay there Okay they have to stay there which is why suckers are needed Loss of digestive system because they're in of it High reproductive capacity because they want to increase their number So loss of unnecessary sense organs Okay presence of suckers and adessive organs Loss of the digestive system and high reproductive capacity These are the special adaptations in parasites Cool Now complex life cycle What about complex life cycle so often involve intermediate host Example human liver fluke So in the case of basically sorry So I'm I was telling about parasites So parasites basically have a most of them have a complex life cycle as well If we talk about the human liver fluke which is a tremid mation which is coming under parathy helmentis It needs both the snail and the fish and also human be So the host basically it needs host intermediate host as well that is snail and fish So don't you think it's a complex life cycle and then they basically come and affect the human beings as well You get it and then there's mal parasite Malaria parasite that is plasmodium It also requires a vector for transport that is mosquito my dear children And this mosquito is also acting like a host So the plasmodium has two host One is the mosquito and also us And apart from that mosquitoes also acting like a vector It helps in transport also So aren't they having a complex life cycle yes they definitely have a complex life cycle Okay Now impact on the host It reduces the survival the growth the production rate all of these things It makes the host weaker and more vulnerable to what predators So obviously that is a really really bad thing So over here we have studied that special adaptation are there in the parasites and they also have complex life cycle Example is human liver fluke which needs two host additional host that is nail and the fish and the malaria parasite that is my children plus plasmodium it needs a vector that is mosquito and apart from that mosquito is going to act like a host as well Okay Now impact on the host obviously it is not really good thing that they do Now the types of the parasites that we have we have ectoparasites ecto as in is going to stay on the external surface Okay they live on the host surface Example lies in humans ticks in the dogs and copoids in the copipoids in the marine fish All of them are ectoparasites They going to live on the surface Now kuskuta which is a parasitic plant It lacks chlorophyll and leaves Okay it does not have chlorophyll Neither does leave You might have seen yellow color plants they spread all over the green plants What do they do what do they do so yellow color plants which are there which does not have chlorophyll and the leaves So basically suppose I am the cusca and this is the plant which is there So I slowly there are certain projections which are come out coming out of my body and gets into the body of the plant into the xylem and phium and taking nutrient from them What is this structure this is known as hostoriia This is known as hostoria my dear children And what am I i am cusuta which is a parasite Now this is an example of an ectoparasite for plants Okay Now mosquito it is not a parasite That is what is written over here Mosquito is not a parasite Please do not go write in the exam that is a parasite It feeds on blood but only for reproduction not for other things Only for reproduction it feeds on blood Apart from that it does not need blood to survive It is not there for survival which is why it is not a parasite Okay Now you have endoparasite the ones that live inside the body For example tapeworm for example human liver fluke all of these things are going to stay inside the body my dear children round worm everything Okay So found in organs like liver kidney lungs RBC etc So more complex life cycle is there and extreme specialization is also observed So complex life cycle and extreme specialization is there then only they can survive inside the human body Now there is one very important term that is brood parasitism but before that I want to make sure that you have studied all the names ectoparasite names lice ticks and copypods kuscuta is a plant parasite mosquito is not a parasite Okay An endoparasite liver fluke you have tapeworm you have round worm all the examples which stays inside our body it have complex life cycle and also they will be having extreme specialization to survive in our body Now brood parasetism is there What is happening in brute parasitism my dear children where one particular organism is going to for example I am a cuckoo Cuckoo is also known as coail Okay And you are crow okay you are crow Now you basically you're going to lay eggs in the nest but me being really really bad I am also going to lay my egg over there What will happen what will happen now basically you do not know and my egg entirely looks like yours So basically what will happen the crow which is there it is not going to be able to find out that it's not mine and it provides nutrition just like how it is providing nourishment not nutrition nourishment how it's providing warmth and all to all the other eggs It does so So don't you think am I utili I am utilizing the other organisms's energy yes so am I not getting benefit out of it yes isn't the energy is the organism losing its energy yes so it is a negative effect for them a positive effect for me so this is known as brood parasitism so cuckoo lays eggs in a crow's nest adaptation cuckoo's eggs resemble crow's eggs to avoid what detection my dear children cuckoo's eggs please remember always remember okay the par the parasite which is there the parasite which is There it is having the adaptation it is having the adaptation to resemble what crow's egg not the crow is not getting adapted to look like coil's egg okay it is the cuckoo that is getting adapted so parasitic adaptation is happening over there work so this is all about parasitism so please when I go ahead do not forget the older ones you can just go back and just read it once more you'll understand things better Okay Now what do we have we have commensalism We have commensalism which is very much interesting So one is getting benefit and the other one is neither getting harmed nor getting benefited So commensalism is an interaction between two species and one species benefits while the other is neither harmed nor it is benefited Example orchid on mango tree So this is orchid on the mango tree my dear children So because orchid wants enough sunlight which is why it goes and grows up there Get it it's not going to harm the plant or anything It has its own leaf and everything It does photosynthesis for itself There is no harm So orchid gain support Mango tree is unaffected Okay What about barnacles on the whale so if you might have seen barnacles are there on the whales So barnacles basically when they stay on the whales they are helping the whales when they move around there the barnacles are also getting transported and by doing this they also are they can easily catch their food as well But are the whales getting affected in any ways no They're kind of okay cool Whatever happens happens we have to be like that Okay Now we have cattleigate and grazing cattle So this is a cattle which is a bird my dear children Yes And now you have grazing cattle So suppose I am the cow When I move around what will happen on the grass the insects which are there they will also fly up And when the insects fly up the cattle will like okay I am going to eat it It eats everything So egg finds food easily as the cattle disturbs the insect when they move around and cattle is basically unaffected There is no effect Now there is clown fish and sea animal So see animal has 10 tackles like this my dear children it has 10 tackles like this and in between you see finding neoimon So over here you have the clown fish Okay And what is happening exactly so clown fish is getting protection because these guys have the tentacles So no one will come and harm it Okay Animal talk about that does it have any apparent benefit so actually I taught this also initially Okay So um what should I say act in actual sense they are getting benefit some benefit is there There's cleaning happening over there and there a lot of other things as well But it is not considered to be mutualism Why if both organisms are beginning benefit it should be considered mutualism Why because actually CNO has a major role to do that is protection It has it has a bigger duty to do which is why it is just counted as commensalism Okay So these four things are examples of commensalism I think now the pictures you can remember it better which is why you may remember the whole thing I could not gather the picture for I actually forgot somehow Okay I'm really sorry for that But yes I hope I said some story or something like that in which way you can remember it Yeah Okay So that is done Commensalism also done Now the last thing that we have is mutualism My dear children in mutualism what is happening it's a type of interaction where both the species benefit my dear children Both of them are going to benefit For example you have lychans you have micorism Okay What do you mean by lychans lyens is a symbiotic association between the fungus and the algae The fungus and the algae that is cyanobacteria Now what will the fungus do fungus will be providing certain nutrients because it can seep down and things like that It can take in the nutrients really easily What about algae algae algae as cyanobacteria they have the ability to do photosynthesis So they will provide what organic matter So fungus provides protection Okay Over here fungus provides protection while the algae produces food And apart from fungus providing protection they also provide nutrients Okay they also provide nutrients Talking about microisa here association is between fungi and plant roots where the fungi help absorb nutrients and the plant provides carbohydrate Plant is also able to do what say photosynthesis right so it will do the photosynthesis It will provide the food What does the fungi do fungi seeps into the soil and brings in phosphorus It brings in phosphorus Exact nutrient if you're asked about please answer phosphorus It is there in the chapter microbes and human welfare Okay So both of them are getting benefited All are happy Yes Now plant animal relationship pollination and seed dispersal So plant provide nectar pollen and fruit to the organism and the animals which are coming for pollination by nature and they are going to transfer the pollen greens So aren't both of them what say benefited yes So this is an example plant pollination Okay Now coalition flowers and pollinators evolve together to maintain their interaction And in this way it has been seen that the flowers which are there and the pollinators which are there they are going to benefit each other with the help of this particular interaction Cool works Will you remember this saler mayorism and this Now there are special cases of mutualism as well So fig and wasp relationship So this is a fig tree Inside the fig tree there are vasps who lay the eggs So fig trees are pollinated by specific species of wasp no one else Now female wasp lay their eggs inside the fig fruit and the lavi feed on the developing seeds So over here the wasp which is there it is getting a safe space to lay their eggs and also nourishment is provided and what does the wasp help the plant with it helps with pollination while searching for egg laying sites So this is a very specialized relationship which is there and is a very important thing that you should know Fig wasp relationship Now there is something else that is orchid and bee Okay orchid and be And this is an example of sexual deceit Deceit as in what do you mean by deceit in Hindi it's dhoka Okay Deceit as in I'm cheating Okay So what is happening over here is that orchids evolve special floral patterns to attract the right pollinators like bees and bumblebees So that picture is not given over here This is of the fig only Okay So basically orchid which is there it looks like the female bee Now the male bee will come Okay female be is over here and it will come and pseudocopy it It will try to coopate with it and this is a cedo copilation because the female is not the female is just the what say the plant that is ofus which is a meditarian orchid my children So Mediterranean mediterranean orchid which is ofus my please no not ofus Okay please remember this name Okay So they are orchids which look just like the female bee which is there Now what will happen the wheel will come and pseudo try to pseudocate But while it does so what happens is that it dusts down all the pollen grains on its body In that way pollination is definitely going to happen Now co-evolution is that if the female bee appearance changes the orchid must evolve to or pollination successful rate success rate will be decreasing That is for sure So co-evolution is really really important over here Got it please remember the name of okay it to showing sexual deceit and in the sense okay at the end if at all okay the orchid anyway is going to provide something even though it's showing pseudo population okay it is not the female uh bee but still some benefit will be given in the form of nectar or fruit or sorry not fruit basically pollen grains or anything okay so it is acting like an example of mutualism itself okay so whatever I'm searching for it is sorted Okay So that's all my dear children So these are the relations that you should be knowing The interactions that you should be knowing These are very very important for your exam and with this we complete the whole chapter So give you big tap on your back You did it Okay So wishing you all the best and also if you have any doubts please please ask me in the comment section And if you found this video helpful then also do let me know If you have any doubts do let me know Whatever you want to say you can say Yeah and wishing you all the best Take care of yourself Do not be worried about anything We are here for you Don't forget to like share and subscribe Bye-bye Take care