[Music] [Music] namaste and welcome to this course on my life ecology I am dr. ancora vidya I am an officer in the Indian forest service of the multiplication Carter so this course is going to have 12 modules with 3 lectures in each module and we begin with the first module that is the introduction to the course and this module will be having three lectures first is introduction to the course second is a historical overview of ecology and third is equality and evolution so let's begin this course with a story now this story concerns a girl who lives in a village so let us call this girl as Miss X and she is living in a village this village is a very beautiful village it is surrounded by some beautiful hills it has a river that passes through it it has some trees around some grassland some fields and this girl is fond of looking at nature and she's very fond of looking at different kinds of birds that are found in this village so there are some flying birds there are some water birds there are some ground bearing birds there are some barricades that live on the trees and so on but then this village also has a lot of infestation of mosquitoes and mosquitoes result in malaria which is a major issue in this village so one day the convent decides that let us take a Plane full of insecticides to this village and spray this village with insecticides to kill off the mosquitoes a very fine idea a number of people would say so and mind you the chemical that is being sprayed here is an insecticide it only kills insects also the company claims so the village is sprayed with insects and lo and behold the girl finds that after a short while all her beautiful birds that were there in the village die off now we this story might appear hypothetical but we are observing such instances in a number of places around the world we have seen situations in which the spray of DDT has resulted in the death of birds now if you spray DDT in a very low concentration because to kill a mosquito you do not require a very huge amount of DDT so you spray this insecticide in a very low concentration and still a number of birds die and when their bodies are autopsied its found that they have a very huge concentration of DDT that is found inside their bodies now let us look at another story now this is a paper which says high levels of PCBs in breast milk of Inuit women from Arctic Kubik now PCBs are polychlorinated biphenyls now these are chemicals that are added to a number of plastics and when Inuit women refers to women who have an Eskimo lifestyle so Kubik is a place in Canada so there are some sqm of women that are living in the Arctic region of Canada and when their breast milk was analyzed it was found that it had a very high concentration of polychlorinated biphenyl now the question arises that Arctic is a very serene place it is we do not go there and dump these chemicals in the Arctic and still in the human population there we observe that there is a very huge concentration of a number of chemicals a number of which are toxic to the newborn babies so some people have even argued that the most toxic food that a human being can eat is the breast milk of an Eskimo woman that is living in the Arctic regions now how do these chemicals reach there and is it important for us well it is important because if you have chemicals in the breast man invariably they are going to reach another human body and in this case the body of a human baby and in certain instances this may even result in very tragic consequences for instance this was a case in which an infant was killed because it was breastfed by its mother and it's and the mother of the baby was they was on some drugs she was taking drugs and the baby died because the baby was getting a very high concentration of the drugs the questions such as these are arising everywhere they are arising anywhere and everywhere on this planet and ecology deals with a number of these questions so if you look at the word roots ecology comes from the Greek words or a course and logos course means a household household where people live so when we say ecology or courses home and law bosses study now we can see eco as a word root also in things such as economics in which eco or I causes home and know me is to count now equality is the study of home it could be my home it could be your home it could be somebody else's home or it could be the home of other animals it could be the home of tiger it could be the home of elephant it could be a marine home and so on now because of these word roots we can have a number of different kinds of ecologies so for instance when we are looking at the population of humans we can have a subject of human ecology if you are looking at different populations we can have population ecology if we are looking at marine environment we can have marine ecology because the marine environment is also a home to a number of animals we can have forest ecology or we can even have things like lattice strain ecology which is a lake ecology so in all of these what we are doing is we are studying the home of some organisms or some groups of organisms so which is why it's called ecology so ecology is the study of life at home at the home of MU me or some other organism so if you went to define ecology ecology can be defined as the scientific study of interactions among organisms and their environment so essentially if we have a forest and then we have some animals here in the forest so let us say that we have an elephant in the forest now this elephant would be deriving its nutrients from these trees or maybe from the grasses below so they also act as food now and when this animal is living in the forest there might also be some other animals in this forest so let us have so here we have say another animal let's say that this animal is a somewhere and this somewhere also eats this grass so we could have competition between both of these animals so this animal our elephant is interacting with the trees it is interacting with the sambar it is interacting with the number of other organisms and it is also interacting and it is also dependent on the environment that is here so for instance it would depend on the amount of sunlight that is there if it is very hot or if it is very cool then probably this animal might not be able to live in that area probably this animal might have to migrate from this area or for instance if we have a river that is passing through this area and if this river dries out so this animal is now not getting enough water so it might have to move out so ecology is the study of all of these so ecology is the scientific study of interactions among organisms and their environment so in this in the system we have the organisms we have the environment and we are studying all of these interactions another definition could be that the ecology is the scientific study of interactions that terming the distribution and abundance of organisms so what we are looking here is the distribution of animals or organisms and the abundance of organism now t2 take another example suppose we have this mountain and in this mountain at this level we have an average temperature of say around 20 degrees Celsius and as we move up the temperature reduces so in this region we have around 15 10 5 0 and this area has an anvil average temperature of minus 5 degree Celsius now the organisms that are found in this zone let us call it zone 1 will be very different from the organisms that are found in zone 2 and extremely different from the organisms that are found in let us say this is 3 4 5 6 so in zone 6 now if you look at the definition again we call it is the scientific study of the interactions that determine the distribution and abundance of organisms now what will be asking here in the case of ecology is what organisms are found in this zone what Argan isms are found in this zone and so on and if they are different why are they different is it because of the temperature is it because of wind is it because of less amount of sunshine that this region gets or is it because of less amount of moisture or differences in moisture that are there in different areas so what are these factors that are determining the distribution of these organisms and secondly what are the factors that are determining the abundance of these organisms now when we say abundance what we are referring to is that if we take any of these parameters so let us say temperature and look at the number of organisms per square kilometer number of organisms of P Xi's X per square kilometer now what we'll observe is that there would be a set of temperature in which these organisms find it very easy or very congenial to survive so for instance in the case of us human beings if our if our surrounding temperature is say around 25 degree Celsius we will feel extremely comfortable so this is the most comfortable zone but then if we increase this temperature - so this was say 25 degrees Celsius now let us increase it to say 40 degree Celsius now at 40 degree Celsius a number of us might not be able to to feel very comfortable so there would be some people who would find it comfortable but there would be a very huge chunk of people who would find it relatively uncomfortable so little less number of organisms would be found in this region or let us increase the average temperature to say 60 degree Celsius and probably one or even zero of us human beings would be found in that region in in that temperature range now similarly if we reduce the temperature to say 10 degree Celsius you would find that less number of people are able to do to find this temperature to be congenial if you reduce it to even less to say zero degree Celsius probably very few of us would be able to live there so we can now draw a curve that is something like this now this curve is telling us the abundance of human beings that would be founded at different temperatures so there is this zone we are arbitrarily defining a dividing this curve into three regions so in this zone we'll have less number of animals in this zone we'll be having more number of animals in this zone will be having less number of animals and in these zones will probably be having zero number of animals now similarly for every organism so for elephant there would be a certain range of temperature in which it will find congenial to survive for the case of tigers there would be a very different range of temperatures for polar bears it will be a very different zone so in the case of polar bears we could even have a situation in which we have a maximum somewhere here so polar bears would probably prefer to live somewhere say around one or two degrees average temperature or maybe even lesser now when we look at ecology what we are asking is the interactions that are determining the distribution and abundance of organisms so distribution what are the areas in which these organisms are able to live and abundance what is their number now these are physical factors but we could also have a number of biological factors so for instance in a forest in which you have ample number of prey animals so if you have a forest in which you have a substantial population of cheetah or sambar you would find Tigers that are living in that area but if you have another forest in which we have very less number of cheetahs and numbers then probably Tigers will not survive in that area because they are not getting enough food so you can even have a number of biological factors or for instance if you have a forest in which you have a very huge density of tigers then probably leopards will not be able to live in that area because they cannot compete with Tigers so leopards would be found in an area where you do not have a very substantial number of tigers so you can have little factors that determine distribution and abundance or you can have biological factors that determine the distribution and abundance now let us recount some of the physical factors now physical could be things like temperature or say rainfall or humidity or wind speed or the depth of soil that is found in that area or the amount of sunshine that the area gets or in the case of marine environments we could even have things like the amount of salinity that is there in a particular segment of water or things such as the amount of sediment load that is there in the water or in the case of rivers we could even have things such as the speed of water so for instance in the case of a river the central region that has greater speeds would be used by certain organisms and the surrounding regions that have lesser speeds would be utilized by some other organisms so these are all different physical factors that would determine the distribution and abundance of different organisms and ecology would ask the question what are these interactions that are driving the the abundance and distribution of these animals now let us look at some biological factors or the biotic factors now meiotic factors could include things such as food so this food could include things like the amount of grass or vegetation that you have or the amount of prey that you have in this area it would also be another biotic factor that would determine distribution and abundance would be the presence or absence of predators in the area so if an area is having a very huge population of tigers then probably etheline sambar would not prefer to live in that area because they'll get eaten if they live there or you can have things such as parasites or you can have things like diseases so a number of these factors play a role in determining the abundance and distribution of the annuals and ecology is the scientific study of all these different factors and their interactions that are determining the distribution and abundance of organisms so what do we actually study in ecology so this was the theoretical basis but what do we actually look at in ecology well we look at habitats habitat is the home of an animal the national home or the abode of the animal so for instance this is the Indian wild-ass and this lives in these sorts of habitats so we have this Indian Wireless Sanctuary in Gujarat and as you can see this is a very plain topography area it hardly has any vegetation in most of the ideas there are some hills that have slight amount of vegetation then this is a very dry area it has a lot of saline soil so ecology would go out and study what are the kinds of habitats that are there in different areas and how are these different habitats determining whether this organism is able to survive in that area or not so for instance we find Indian violence only there we do not find it in say West Bengal because the the habitats that are provided or that are available in West Bengal are very different from the habitats that of labeling with wrath and similarly we have the Royal Bengal tiger that is found in West Bengal but it's not found in Gujarat so ecology would go and ask the question what are the different kinds of habitats that the organisms get in different areas then it would go out and ask what is the amount of biodiversity - we have so for instance in the previous image we saw that we have this Indian wild-ass and there are hardly any other annuals that are seen here and also the the kinds of grasses that we have all the kinds of vegetation that we have here is very different from say something that will find in birth poor now birth poor is a bird sanctuary and in this area will find a number of birds will find and this area is regularly inundated with water so in this area we'll be having a number of water birds will be having ground dwelling birds will be having a number of birds that live on these trees though even the vegetation in this area will be very different because this area has ample amount of water so the kinds of trees that will live here will be very different from what we are finding there in Gujarat so the next question that ecology would try to study is the level of biodiversity that we have what are the different kinds of species that are found in each area what is their abundance and distribution so for instance if we look at this area do we have say 1,000 Birds of this species and say only ten Birds of some other species or do we have equal number of birds of all of these different species so that is also another topic that is studied in ecology next we look at population interactions now population is a group of animals that are living together and they belong to the same species so for instance in this image we can see a troop of macaques so we have these macaques and if you look at these two animals the this animal is grooming this second animal so what are the kinds of population interactions how do they behave together why do they behave in this manner so for instance what is the profit or loss or the gain or loss that is being provided to this animal by grooming this animal because in the first instance it might seem that this is an act of altruism this animal is only grooming this annual and not getting anything in return now such a system might not work in practice so in any case this animal should give something back to this animal that was grooming it so how do these interactions work in these populations how is this animal able to give back to the first animal are the kinds of things that will study in ecology next we look at community interactions now community is a group of organisms that belong to different species and they are living together so for instance in this image this is from Kaziranga we can see we have a buffalo we have some scavengers in the form of vultures and then we have a number of different trees here different species now community interactions means what are the kinds of interactions that are being held between say this Buffalo and the scavengers or between the busting between the Buffalo and the trees and so on so for instance in a number of trees we have a phenomena that is known as ruefully now zoo fillies who is animal and filly is love now zoo filly is a situation in which you see have a tree and this tree bears fruits and then these fruits are eaten up by a bird and when this bird eats up this fruit it gets nutrients but at the same time the seeds also get inside the word so now the seeds of the tree are inside this bird and then this bird moves to say some other location so let us say there is an electricity line and this bird then goes there and then this bird defecates these seeds out here and when it difficult you have all these seeds that have fallen onto the ground and then after a while after the next rains we'll have some small plants of this tree that grow up in this area so in this case this tree is using the bird as a vehicle to transport its feeds so zoo is animal soap it's using this animal which is the bird to transport its seeds so again in this case we can see that there is a one-to-one interaction or a give-and-take relationship between both of these organisms the tree is giving food to the bird and the bird is giving a transport mechanism to the tree so here we have organisms that belong to two different species and they are interacting in a way that is mutually beneficial to both of these now similarly in this situation if we have the Buffalo is it helping the trees or is it harming the trees or some other vegetation similarly if you look at these vultures are they helping the system or they are or are they harming the system and how are they doing that so these are the kinds of interactions that we observe in a community and this is also a topic of study in ecology now ecology also looks at the impacts or the effects of different changes that are happening on our earth so for instance this is an amazing game from Gujarat and here we can observe a number of goats and as you can observe here we have these sand dunes and we also have a very scanty vegetation now if you have vegetation somewhere so the roots of the plants are able to bind the soil or are able to bind the sand in this region now if you have goats and if you have a large number of goats that are going there and eating away these plants what will happen in a short while is that these after these plants get removed the sand will be able to move freely because it's now unbound and so you will have a situation in which the amount of erosion would increase in the system or for instance earlier this area was having some vegetation and so we had a situation in which this area is it a semi-arid area but once you have removed all of these plants and you do not have any further seeds that remain in this area this area will become completely barren it will become a complete desert so things such as these things such as desertification that have been brought about by some human activities are also topics that we study in ecology so effects of changes so these are some topics that we study in ecology but how do we study these so there are three approaches to ecology the first is called the theoretical approach now in the theoretical approach we use equations and models in an evolution manner to understand what is going on in the system so for instance to give an example you have say a predator and you have a prey population now if the number of prey increases then we'll observe that the number of predators would also increase because they are getting more amount of food and because they are getting more amount of food they will be able to to to devote more resources to reproduction so an increase in the prey population would increase the predator population but then if you have more number of predators because of this increase that would provide a negative feedback so a negative feedback to the prey population because now because you have more number of predators so these predators would be preying upon the prey population and would reduce their numbers so this would reduce it down now if this number reduces if the number of prey animals reduces that would again go back and reduce the the population of the Predators and when that number reduces that would again give a feedback that would increase the pre population so to put it in other words if you have more prey that would give you more Predators now if you have more predators that will result in which a number of prey animals are eaten up which would result in less prey now if you have less prey so you'll have less amount of food that is available to the Predators so that would result in less number of predators because less number of prey population is able to support a lesser number of predator population now if you have less number of predators the prey would be able to increase so then we would be having more number of praise now this is something that we can understand intuitively now if you go to the theoretical approach so theoretical approach would begin with such a framework and would then go on and define different equations and different models through which we can understand the system so for instance if you have a population that is represented by small P and predator population that is represented by capital P so the our theoretical approach would ask that if you have this prey population it would be a function of the predator population and the existing prey population and what would be the equation through which we can model this system and we'll have an example so this system is governed by what we call is the load curve volterra equations and we'll have a greater look at this system in more detail in one of the later lectures now the second approach to ecology is a laboratory approach so laboratory approach uses the scientific method of formulating hypotheses and testing them through experiments so to give an example suppose we have this area and so suppose this is a pond and in this pond we are having a very less amount of algae now the question that we could ask here is what are the factors that are limiting the the Algy population in this pond so again we are looking at the abundance and distribution of an organism in this case this organism is algae and now we are asking the question what are the limiting factors in this pond because of which the population is less so what we can do in this case is that we can divide this pond into different regions so we can set up curtains and once we have set up these curtains we have these different regions 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 now once we have set up these curtains water cannot move from one of these areas to the to another area so all of these zones have now become different from each other now what we can do is that say we have a hypothesis that that we have a less population of algae here because there is less amount of nitrogen that is available to the plants so in that case what we'll do is that in this area will add nitrogen maybe there is another hypothesis that this could be because of less amount of phosphorous that we have in this area so in another area we'll add phosphorus in another area we'll add potassium and so on so we can formulate n number of hypotheses and then we can perform this experiment we can alter all of these different factors maybe you could even have a factor of temperature so probably temperature is very less and so your plants are not able to grow here so probably in this area we'll put up a heater and we'll heat up this water or probably temperature is too high so in another area we could reduce the temperature or in the case of these nutrients you could have a sector in which we reduce nitrogen we reduce phosphorus we reduce potassium in some other areas we add iron in some other areas we reduce iron so we can perform n number of experiments and in all of these experiments we'll keep certain areas as controls so control is a sector in which we are not doing anything so this is how our system was without doing any of the interventions so in this approach what we'll do is we'll formulate hypotheses that we can have these n number of reasons because of which we are having less number of or less population of algae and in these waters we could have a deficiency of certain nutrients we could have in excess of some nutrients that are becoming toxic to these plants or maybe we could have less temperature higher temperature less amount of sunshine more amount of sunshine we can formulate a number of hypotheses and then within perform experiments to check all of these so we can alter all of these different variables and then we can check them with the controls so probably it turns out that in this experiment see there was an area in which magnesium was added magnesium was reduced or say chloride was added or fluoride was reduced and so on so probably it turns up that in all of these different areas nothing changes but in the area with magnesium we can more number of plants that are that have come up so once this happens we'll be able to tell that we have a less population of LG in this pond because of a deficiency of magnesium so this would be a laboratory approach so we are using the scientific method of formulating hypotheses so the first step is to formulate hypotheses what are the things that could be playing a role in it in having a reduced population and then we can test them out using experiments so we look at the theoretical approach in the laboratory approach the third approach is the field approach so field approaches through observations in the field now a very good example of the field approach is what we refer to as the longer keitel Association now this association between these two species was figured out in car now so what people observed was that if you have a big tree and in this tree you have some longer population that is a troop of Longwood's that are there on the streets you will also find a number of titles that would come below this tree so what are the factors that are resulting in this particular distribution of animals that wherever you get long goes on trees you find Kittles coming there so what people did was they just sat and they observed what are these long goes doing to the sheetal's so they observed that if you are a languor and you are on top of a tree you have a very good vantage location to observe the surroundings so if you have a tiger that comes up here and if you have these tall grass lengths so you have these grasses that are there so a cheetah will not be able to observe the tiger but a longer route will be able to observe the tiger and whenever this animal observes that either it starts giving out false alarm calls so that other long roots are also a la that there is a predator nearby now when this happens the and you have a cheetah that is also nearby so cheetah also hears the alarm so even though your Keitel was not able to see a tiger because it was there on the ground it was not poaching high up on the tree if it is close to the longest it can make use of that information so that is one benefit that is provided by the lung goes through the sheetal's secondly whenever the lung hoods are eating the leaves of the tree they tend to be a bit destructive feeders so what they they'll do is they'll pluck up a leaf then eat a bit Spade you'll and they'll throw the rest of the leaves down now especially in in in seasons where you have scanty vegetation or you have less number of green grass status of label so say in the summer season you'll you have this area that is that has all the dry grasses now dry grasses are mostly unpalatable because they have a very high amount of silica content if sheetal is going to eat over or dry grass it is going to injure its mouth so it requires green vegetation now when it is when it comes to the bottom of this tree a Longwood that will be be plucking a leaf eating its padule and throwing the rest of the part down so chizel will automatically get access to this food resource so this shit'll it it is unable to climb up a tree and it is unable to get those leaves by itself but by coming in close contact with the lung roots by just coming where the lung boots are eating and it can eat now all the leaves that are falling from the trees so this is a kind of observation that can only be made in the field now similarly why does longer tolerate ethyl's when it is there because a languor is getting a viewpoint from here it is not getting a viewpoint from here T cells also have a very good sense of smell so probably if you have a tiger here and Elango was not able to see this tiger and the wind was blowing in this direction so teetle was able to get a sense so when Keitel a sense of this predator nearby it will also give out an alarm call it would run away and that would alert the Longwood's so essentially this kind of an association in which you have two different organisms that are interacting with each other or a community interaction can also be study studied using the field approach in the field approach we use observations in the field so these are three approaches to equality and in the rest of the course we'll make use of all of these three different approaches to understand why an organism is somewhere by an organism is not from somewhere else and what we can do to help these organisms or to conserve these organisms so these are the three approaches to ecology the theoretical approach the laboratory approach and the field approach so in this course we'll be having so let us now have a look at the outline of the course so we'll be having twelve modules in this course the first module is introduction introduction to the course a historical overview of ecology which will tell us who did what to make the field of ecology what are the contributions of different people different scientists who made ecology the field that exists today next we'll have a look at ecology and evolution does ecology drive evolution and if yes how does it do that the second module will be about ecological structure so in structure we'll have a look at the levels of organization so when we say a population of animals or a community of different organisms what is an ecosystem and things like that so we look at different levels of organization and how this organization helps the system to survive next we'll have a look at which is abundance and distribution or biodiversity and we'll look at it in greater detail in the third lecture the third module is ecological interactions so we'll have a look at positive interactions and negative interactions and the study of behaviors and behavioral ecology the fourth module is ecological energetics so in this module we'll have a look at food chains food webs and trophic levels and we'll also understand how and why are the birds dying because of the insecticides we'll have a look at primary production so primary production is how plants make food out of sunlight and we'll also have nutrient cycles say carbon cycle nitrogen cycle and so on the fifth module is population ecology now population is a group of animals that belong to the same species so say a group of cheetah or a group of sambar that is a population now if we want to study a population we'll have to define a number of population parameters so what is the number of organisms that are there what is their sex ratio how many offsprings are born to each mother and so on we'll also have a look at different demographic techniques to get an idea of these population parameters next we'll have a look at population growth and regulation so for instance say we wanted to conserve Tigers how does this Tiger population grow why is it not that we put Tigers into a forest and the in this population shoots up what are the factors that regulate its growth and what are the factors that may even lead to its decline are things that we'll understand in this lecture next population studies and their application so this is more of an applied topic the sixth module is about community ecology community nature and parameters changes and ecological succession so succession is a process in which the ecology changes or the ecosystem changes from one state to another state so for instance if you have say a piece of barren rock so on this rock after a while we might observe that some algae grow up and when you have some algae on these rocks so after a while they would start degrading this rock converting it into soil once you have the soil there then you might have some other organisms that come in say you have grasses that come into this rock rocky region once you have these grasses they'll degrade the rocks even further and make way to say small plants followed by some trees so this is the the process of ecological succession so in in the process of ecological succession every species makes way for the next species till you reach a climax so we will have a look at ecological succession and also community organization now the seventh module is about distribution and abundance so we have biogeography that is the analysis of Geographic distributions next we have fire things where they are what are the factors that regulate this distribution and abundance and we'll have a look at some push and pull factors in greater detail the eighth module is management of threatened species so what are the different kinds of threats that we have two different species so there are a number of species that we are trying to conserve we have five years we have elephants and so on so what are the threats that are being faced by these species and what can we do to reduce the impacts of these threats to be divided into incident three to conservation and XE to conservation the ninth module is topics in human ecology so we'll have an introductory session followed by human population growth and food requirements and sustainable development the tenth module is ecology of change so we'll have impacts of climate change impacts of plastics specially on biodiversity and impacts of oil spills the eleventh module is applied ecology so we have the optimum yield problem biological control and ecotoxicology and pollution management and restoration ecology and then we'll devote a week to revision of all the topics that we have covered so far now in this course we'll have a continuous assessment so the assessment will be in the form of assignments and in the form of a final exam assignments will comprise multiple choice questions which will be based on the week's topics and in the final exam will be having three kinds of questions so we'll be having final exam in two different sorts a morning cotton and evening sort and we'll be having three different kinds of questions will have recall questions so recall questions are those questions in which you have to give an answer based on recall from the lectures then we will have some questions that will come from the assignments maybe slightly modified but more or less based on the assignment and third will be open type questions that will test your or your wider understanding of the whole topic and the final exam will also comprised of multiple choice questions now the final exam will be computer-based and will not require you to write any rain the answers so in this lecture we had a look at what ecology is what are the different kinds of topics that we study in ecology what is habitat what are the kinds of interactions that we have what is a what is a population what is the community and so on we also had had a look at at three different approaches to ecology we have theoretical approach we have a laboratory based approach and we have the field approach and we make use of all of these approaches as we move forward in this lecture so thank you for your attention [Music] [Music] [Music]