So till the last class we were looking at the energy flowing and the what is known as
the efficiency which energy is flowing through various tropic levels or the food web or what
we call us the food web, how the energy is flowing through the system by converting matter
that’s available to living systems.
So essentially the solar energy that comes into the, the solar energy that is received
by the plants or the producers is converted to energy and that converted from the producers
the primary consumers take up the energy which is about one tenth of the produced by the
plants, and then when it goes to the next level, when it flows to the next level that
is the secondary consumer, again the energy reduces by one order of magnitude and then
when it goes to the tertiary consumers that’s example is given as humans, it again reduces
by 10%, by one order of magnitude.
So in general one can say that the ecological efficiency varies between though, it varies
between 2 to 40% in different individuals or different organisms and different species,
but 10% efficiency is a common thing that runs through the living systems that we see
around, so this is known as the 10% low with the efficiency or the ecological efficiency
that is energy is flowing through the systems.
So the energy flow in the ecosystems is actually estimated as I said in the last class is using
productivity and efficiency in the case of plants we use the term net primary productivity
and so that can be calculated using various methods and one of the methods of harvest
method was detailed in the last class, so there are many methods were direct measurements
are possible which are harvest method, oxygen measurement, carbon-dioxide measurement or
like aerodynamics methods where dynamic method were again carbon-dioxide flux in a community
is measured using different sensors, carbon-dioxide sensors so that you get a concentration of
carbon-dioxide that is flowing through the system at different times and different periods
of the year.
Then in aquatic systems we have to use PH method which is again a measurement of the,
amount of carbon-dioxide that is dissolved in the water systems, so that you can find
out how much carbon-dioxide is released by the producers, the primary producers which
are there in the water or so the concentration of, how the concentration of carbon-dioxide
is varying in the aquatic systems because carbon-dioxide is used by the plants for producing
biomass and oxygen is released to, while photosynthesis is going on.
Similarly these direct measurement methods are not possible, there are indirect methods
for example a large forest area if one wants to find out the productivity there are indirect
methods such as leaf area index that is the area of leaf that is exposed on one side to
the sunlight which can be measured by, by measuring the green index or the green reflected
right from the leaf surfaces can be measured using satellite imaginary, so that is also
possible for large areas where you want to find out the amount of sunlight that is received,
that could be effectively used by plants.
But then this measurement has some disadvantages like if it is a dense canopy or forest it
may not be possible to find out a different layers of the leaf how much energy is being
harvested or how much light is being used by the plant.
So based on this terrestrial ecosystems and aquatic ecosystems are classified based on
the average in net primary productivity that is based on the plants that occupy this spaces
or this systems, so you’ll be fine that you know swamps and
marshes and tropical rainforest of the highest productivity in terrestrial ecosystem among
terrestrial ecosystems, and among aquatic ecosystems estuaries are equivalent to the
swamps and marshes and tropical rainforest that you find on the terrestrial ecosystem,
among the terrestrial ecosystems.
Now when it comes to the next level that is when the energy is transferred to the primary
consumers or the secondary consumers, the efficiency with which energy is transferred
is known as ecological efficiency of animals, so for that one needs to, how the energy is
flowing through an animal population if one needs to figure out it needs what is known
as detailed energy budget which will be done using the loss of thermodynamics and the heat
flow that is taking place in the animal populations.
So there are some modeling that is required to find out the efficiency with which animals
are using up the energy that is flowing into that system in the form of food, so the food
that is taken up by the animals for the growth and reproduction and the energy that is flowing
in this systems will be, it has to be determine for all individuals of all ages at all times
in their lives whether they are young or old, and whether they are resting or active then
only we get approximation of the efficiency with which energy is flowing into that system.
So the efficiency of that energy flow is again determine by the output by the input into
100, so the output is basically how much is the, that is stored in that particular level
of tropic level as biomass divided by that of the energy that is flowing into the system
that is a food taken by the animals that is taken, so some amount of energy is wasted
from the animals in the form of excretion or respiration or activities which are again
respiration will be indirect measure of the activity and also you can figure out the amount
of the undigested food that comes out of the system.
So the effective amount will be that what is use for growth and reproduction will be
the amount of energy that is assimilated by the animal.
So when it comes to, so now we have talked about the energy flow and the material flow
in ecosystems and the energy that is flowing is converted to materials with some loss at
different levels, so the loss is quite high so the efficiency with which energy is flowing
is only about 10% in different levels.
So how this, now when we look at this the matter that is circulated in the biosphere,
there is some amount of organization that one can see in this.
So now if you take a look at this picture here, it’s an upside down picture which
is showing from atom to biosphere how we are related to each other.
So if you look at this picture one can see that, you can see atoms from molecules, molecules
are the constituents of what is the living, the first from primary structure that we are
interested, the fundamental structure and functional unit of life is a cell.
So a cell, multiple cells organize themselves and form what is known as an organism, so
that’s with an organism which is organizing different cells to, but at the same time serving
a purpose of different functions in their body with different functions, but at the
same time function single individual which can move about, which can gather its food,
which can think for return, or move, or organize itself, do various things, for activities
like whether it can jump or walk or whatever.
So an individual living being is something that is formed from different cells and then
forms from individuals of a group, so in this case a blackbuck is shown as an organism here
which is grazing in grassland.
And the next picture shows a population of blackbuck, it could be a population of, a
population of cows or a population of elephants or a population of lions or jackals or tigers
that we talk about, so it forms a population, a group of individuals of the same species
living in a particular place, so that they are known as a population.
And when different populations of different species living in a particular place that
is known as a community that is a next level, so if you go to any particular place or grassland
or if you go to forest you will see different species, population of different species coexisting
together in that particular community, so that forms a next level of organization, so
but they have again at that level also if you look around there is some organization
and each community is living within its means and it knows how to use the energy and the
material that is flowing into the system.
And the next level is ecosystem that is basically the community of different species that interacting
with one another and with their nonliving environment of matter and energy, so when
we are talking about population and community we were not talking about the nonliving environment
of matter and energy though they are also interacting but when you have to see a system
level, ecosystem level you have to understand that a community of different species which
interact with one another, and among themselves and interact with each other and also the
interact with the nonliving environment of matter and energy.
And one has to remember that ecosystems do not have solid boundaries, they have what
is known as ecotones, so they merge with the surrounding system which maybe another ecosystem,
for example if you take a pond or a lake or a river, you see that though the boundaries
are what we think are the water body but that’s not strictly a boundary, they softly merge
with the surrounding other ecosystems or other communities, through what is known as ecotones
or buffer areas or buffer sounds of those systems, so for example a lake water boundary,
strictly we can’t say where it will be in summer or where it will be during a flooding
season, so that dictates that the boundaries of the lake for example can be moving back
in forth.
And the surrounding areas of the lake if you take it will be more moist and wet and the
plants and the other species that you see will be very different from little far away
from the lake surroundings, so there is this gradual change in the living systems that
you find around an ecosystem due to this soft toning of the living systems that you find
there.
And in different ecosystems combine together we find the biosphere, so biosphere is nothing
but the parts of the earth, it’s air, water and soil where life is pond is known as the
biosphere, so there is a blue envelop that connect this 5, top 5 levels of this that
is what mostly ecology is dealing with, so ecology deals with organism, population, community,
ecosystem and biosphere.
The cell studies mostly are dealing with biotechnology and other areas or genetics, they look at
cells or molecules and then see how to manipulate them and which might affect organisms or population
or community or even ecosystems at different levels, so because they are link through this
particular connection that we can see here and the order that you can see in the, at
the different levels.
Now when it comes to ecosystems why the questions that we ask are, what do we call as diversity,
so one of the first questions that comes in terms of, the question is like why so many
kinds of plants and animals, so why didn’t it be like you know all organized in a uniform
way and you can have one species, one level, even if it is energy flow you would have had
only one species of plants, you could have had then the next stage level of energy level
flow if you required you just one species of animal it could have been you know uniformly
spread, so why we see so many different kinds of plants and animals.
And then the next question is why should individual animals and plants be organized into regimented
populations of look-alikes and behave-alikes.
Look into different regions for example those who know a different birds let’s say, we
commonly see crows around us, how many of us look and see that there are different types
of crows that we see around, so there are at least two types that you see around when
you look, one is a completely black colored one, the other one which has a little ash
head and it is smaller in size with a smaller bill, and the black one will have you know
large bill, so this two are look-alikes and they also behave alike, but at the same time
they are not the same species, they are two different species, so this is what is meant
by, why should individual animals and plants be organized into regimented populations,
why do we have this look-alikes and behave-alikes?
So this actually is, we have all heard about the origin of species by Charles Darwin, and
this is the ecological part of the origin of species, how different species are originated
on earth.
So the answer to the first question that why so many kinds of plants and animals that we
see around.
Answer is a successful way of life brooks no variance, or in another words to be deviant
from the characteristic job that this species is doing, it exacts a penalty in fitness,
so traits inherited from parents or successful traits and they are changed only at peril.
So each species is characterized by what is known as the trade, okay, it’s like saying
that somebody is practicing carpentry or somebody is practicing teaching or somebody is practicing
particular trade or somebody is an electrician who is practicing it.
So when you transfer this knowledge to the next person and that person does not impart
the same knowledge then there is a problem in executing the job with perfection, so it
is almost similar to that.
So if a species is something that practices particular trade or particular way of life
that it can, it can leave in the in its surroundings and in its environment, so this requires certain
types of skills or certain types of adaptations we call, let’s say a long beak or a long
neck, long feet or a web feet, so different kinds of adaptations that we see in different
animals, so animals it is easy to see or different plants for example, long leaf, short leaf,
broad leaf, colored leaf, non-colored leaf, there are so many differences that we see
around, these are known as the trades that are inherited through genetic source or genetic
diversity from parents and then it is successfully transferred to the next generation by through
reproduction.
So now when it comes the vision of a species, so what is a species?
It’s a collection of individuals with a common trade, so which is why they called
a, which is captured in what is a term called niche, a niche.
So a species is a collection of individuals with a common trade that is captured in niche,
so this means two species of approximately same food habits are not likely to remain
long evenly balanced in numbers in the same region, so one will crowd out the other so
which means some kind of competition that will set up the vision of competitive life
says that food needs must be distinctly different for populations to coexist, otherwise both
the populations will start to compete for the same food source and then they will, one
of them will outnumber the other one.
So how is the limit set to this possible way of life that can coexist, so there are various
ways in which this can be modeled, so that we will be discussing later, so the logic
of for different species is that individual of a species population have closely similar
needs of resources that is they live in the same niche.
And when crowded limit is set to species population by a competition for resources, a population
history leading to crowding and resource limitation can be described mathematically, so that is
where we come into describing what is known as a population dynamics and how population
is varying in a community, so if you take a species or a community or different levels
that we have seen in the earlier chart, so ecosystem is form from communities and communities
are forms from population and population is form from organism.
So at the levels of population and community and then ecosystems we have to look up for
the population dynamics or how different species are interacting for example when it comes
to community you can see population of different species living together, how can they live
together?
If their food needs are same, can they live together?
Or how many numbers can be there is each species?
These are the questions that one needs to address at this levels when it is coming to
population and communities, so that’s why the question of population, how do we determine
the population?
So what determines a population?
So population number or the dynamics is determine is to leading to crowding and resource limitation
can be described mathematically.
So pairs of related species can be found with enough overlap in the resource needs that
they can potentially come into competition with each other,
so as I said earlier when we look around in our own surroundings we can see two species
of crow, so do they have the same food needs or do they specialize with something which
is slightly different from each other.
So these are possible ways in which ecologist go around and look and study the behavior
of those organisms and that can be related to its niche and how they find out their special
resource requirements and how they vary from one another in their specializations, so there
will be some adaptation maybe possible for one of the species, one maybe a journalist,
the other maybe little more specialist and which maybe eating only certain food, okay,
or one maybe seen only in certain environments for example if the black crow which we see
around are not very commonly seen, whereas the crow with a grey head or the little less
color and the small one which is known as the house crow which is very very common everywhere,
and which is probably journalist and can feed on many common food that we see around or
food waste that we see around, whereas the other crow may not be that common because
it may not be feeding on every kind of food that is available, maybe it is specializing
or has a niche that requirement that is different, slightly different from the other species
though they can overlap in their food needs, but they may not be exactly crossing their
paths.
But at the same time one can also observes that their population numbers if you look
at they are different in numbers, one of them is not so common, the other one is little
more common, so this also could be same that the same that what is shown here the pairs
of related species can be found with enough overlapping the resource needs that they can
potentially come into competition with each other, and so one is crowding out the other,
so one will be more in number, the other one will be less in number, and so that’s how
it goes.
So what is a niche?
So there are very different definitions for niche and so every species has its niche or
a unique position in a food, web or ecosystem, unique function in life or a unique set of
resources or factors needed for survival.
For example if you take a sunbird which is an equivalent of a hummingbird which you see
in the temperate climates, what we see in India are sunbirds, so if you look at them
what is a unique set of resources that they require is nectars from plants or you know
from flowers, so they collect for example there you know in the process they also serve
certain function in the ecosystem, so during the process of nectar collection they also
help in or aid in pollinating the plants through going from one plant to another.
So similarly there are so many insects that we see around, they also have unique resources
so each insect maybe approaching a different kind of flower or a plant and it is not that
all the plants will be visited by the same insect or different species of plants will
be visit by different kinds of insects, so there is a unique niche that we are talking
about for a particular species, so that determines what, where they can survive or where they
cannot survive, let’s say if a particular bird is feeding only on a particular plant
and that plant disappears due to some disease or let’s say some catastrophe or a drought
or something like that, so it is possible that the bird will also disappear because
of this connectivity between or the specialization of that bird for that particular species of
plant.
Similarly niche also can be defined as a community function, so there are various definitions
for niche, so one is the definition of niche has a community function that what function
does it serve in the community, this was defined by Elton in 1927, so he defined niche as the
animals place in the biotic environment, it’s relation to food and enemies, okay, so it
is known as a Eltonian niche, so what is meant by, each animal has a place in its biotic
environment and it also has a relationship to its food and its enemies, so for example
certain birds if you take, they maybe food, they make take some food from their environment
and at the same time they maybe food to something else.
For example if you take frog, a frog will be taking food from the, from its surroundings
it maybe capturing some of the insects around, but at the same time a frog is also food to
snake.
So similarly, so it is a community function, it is serving a community function so it has
a function that it is serving here.
Ecological equivalence species will comparable niches in ecosystems of different places,
so that’s a consequence of this community function, so equivalent species that what
we see in different for example if you take the latitude or longitude of earth and then
go around finding what species we find, for example if you take equator and then walk
from one end to other, so if you walk around on the equator let’s say from one end to
the other, and you will find that so many varieties or different kinds of plants and
animals that they can see which will places on niches and ecosystems of different places,
so this could be due to various reasons like the rainfall that is received in different
places will be different, so the plants and different species which may come up there
will be different.
The temperature that will be, that is existing in a local area will be different, this also
can result in, so mostly what dictates is the rainfall pattern that dictates a vegetation
in a particular area or in ecosystem and this further dictates what kind of species which
are dependent on those plants come up in that particular area.
Second definition of niche is, niche in the species definitions, so for example Grinnel
in 1904, niche has a property of an individual species population, so which means a specific
set of capabilities for extracting resources for surviving hazard and for competing coupled
with a corresponding set of needs.
It’s elaborated here below myna is a bird that we see around everywhere, it plays a
role in the community as a you know worm puller or food, worm puller or it eats also certain
insects, it’s not exactly worm puller it eat insects, mostly grasshoppers and other
insects like that.
But at the same time it’s also let’s say food for eagles, and eagle can you know hung
and feed on a myna which is its definition of us a class one niche.
And similarly myna not only eats grasshoppers and it also avoids eagles as part of the program
working to trust more mynas into the next generation.
So what we see is that myna is serving two functions one is that it is taking insects
from the environment like grasshoppers or other insects and then it is also being food
for, being served as a food for some other species that is the eagle.
Third definition of niche is as a quality of the environment which is known as a class
three niche.
A niche is that set of ecological conditions under which a species can exploit a source
of energy effectively enough to be able to reproduce and colonize further such sets of
conditions, so this is the further definition given for a niche which is in the ecological
context, it has to be defined as a niche is a set of ecological conditions that you know
a species can exploit a source of energy effectively, it’s effectiveness is dictated by how much,
whether it is able to reproduce and colonize furthering the using of this ecological conditions
available to the particular species.
Then this case the niche will become a multidimensional hyper volume of resource axes because there
maybe multiple resource axes that are possible to which a species can extend itself and make
use of those axes.
So when it is the, so it’s also is like that when niche is a quality of the environment
or the class three niche what we define, two classes of niche axes can be separated by
their probable effects on the size of the hyper volume, so for example if a species
population lives without competitors or other organisms that would interfere with it, then
the size of the niche should be set by physical needs and food alone, so this is known as
the results and what is known as a fundamental niche of the species if there is no competition
the species will make use of the available food and it grows in its number or the population
grows.
So in such cases when the fundamental niche is growing, so now when it comes to this species
and population, the important concept that comes in niche how the population dynamics
or the population number of in members in individual species, how they are controlled?
Let’s say in this case when niche as a classic quality of the environment when it is the
class three niche we are defining, a species population lives without competitors or other
organisms that would interfere with it let’s say, then the size of the niche should be
set by physical needs and food alone.
How is the number of the or the number or the population of a particular species is
controlled, let’s see if there is no competitors or if there is nothing interfering with the
lives of that particular species, in that case what we define something called a fundamental
niche, there is no competitors and there is nothing else, there is only food and physical
needs that are met by the individual species, so this is described using what is known as
a logistic model of population growth,
so one can see that in on the X axis you have time, and on the Y axis you have the number
of individuals or animals in the particular species how it will grow in the absence of
any competition.
So this is known as logistic model and it has a sigmoid growth curve which as you can
see, it’s a growth which is slow initially then it picks up with the very high rate and
then it terminates of to a levels of to a study number, so what dictate this growth
curve and what dictate its study state that it reaches after certain time.
So as we said already it is dictated by the container in which it
is growing or the sources available to that population, this is in the absence of any
competition, so the logistic model can be expressed using the equation logistic equation,
so population regulated by crowding to an equilibrium number can be modeled using the
equation that is R is equal to small r into N into 1-N/K, where this capital R stands
for the population growth rate that is given by DN/DT, so that is N is the number of animals
present at time T. And so now if you say that K is the number
if the number of animals able to live in the container, so if you imagine that we are growing
some algae in the container and we are providing some food to the algae, and it is growing
in or some let’s say paramecium or a single cell organism or some bacteria is growing
inside a particular container, but it is not allowed to go out, so how much number, how
many numbers can grow inside that container?
Or let’s imagine that you know a boundary wall which encompasses let’s say a population
of deer, how many can they grow?
Will they outnumber or can they keep on growing without any limit or will they be controlled?
The population will be stabilizing or will it be reaching some kind of equilibrium?
So that’s a question addressed in this logistic model in the absence of let’s say predator.
So in this case the number R is the population growth rate that is the DN/DT, N is the number
of animals present at time T, and K is the number of animals that are able to live in
the container at population equilibrium that is the value that you can get on this logistic
curve when it reaches the equilibrium that is, this value is K.
So at any given point of time the population is growing with different rates, so and small
r is the intrinsic rate of increase that is how much a number is increasing that is depended
on the growth, the birth rate and the death rate of the animals that’s what give you
the small r value.
The logistic equation can be applied where the population growth is continuous, okay,
so basically there is no interference in terms of any predators or anything else so the population
is growing continuously, so continuously how long can they grow is the question, so as
long as food is available to the system, available to the individual members the growth will
continue and then they will reproduce and multiply and the population will grow, so
then once it reaches the capacity of the container that is the limit to which it can grow, that
is the number it can hold, this is known as the carrying capacity, K is known as the carrying
capacity of the system which is crucial to the logistic statement, and once it reaches
the value K so then N becomes equal to K so you can see that the value, that DN/DT will
become equal to 0 because 1-1 it will become 0 and so you can see the growth rate will
become 0.
So the logistic hypothesis states that as the population number N approaches the saturation
number K, then RN becomes 0 and the population growth ceases.
So no organism can, so the sigmoid growth histories reflect changing intensities of
competition, and fecundity or the rate of
which individuals produce offspring should be high when there is plenty of food supply
that is high intrinsic rate of increase and that’s what you see in the sigmoid curve
in the middle region when there is plenty of food there will be lot of growth.
And when the number of individuals increase, the food availability individuals will decrease
and then they will reads the carrying capacity of the system.
So the fecundity or survival or both should drop when there is crowding, so once the growth
reaches the K value or N becomes equal to K, the container is almost full with the animals,
so basically it cannot grow further, so it starts dropping.
So you can multiple ways, so if you continue to supply external food source then the growth
curve can keep growing, increasing, or it will decline because the individuals the intra
species competition or the competition among individuals of th species will come into the
picture and then they will compete for the resource of the food and the population growth
will slow down and or cease altogether.
The logistic hypothesis is also a hypothesis of control by density, density dependent factors
that’s the denser the crowd, the more the competition, so that’s what would happen
there and then the growth will again be self-controlled.
The logistic hypothesis can be manipulated to predict the results of in this specific
competition between species populations with overlapping resource requirement.
Now let’s say if you have two different species competing for the same resource, so
how will it be described?
So this is what we call as competition, so the competition occurs whenever a valuable
or necessary resource is sought together by a number of animals or plants, it could be
nutrient by different plants or it could be a resource food resource by different species
of animals let’s say.
So when that resource is in short supply, so let’s say there is a resource is in short
supply then there is competitions setting up, or if the resource is not in short supply
competition occurs when the animal or plant seeking that resource nevertheless harm one
another in the process then also competition can result, there is no need for you know
the resource to be in short supply, so even if let’s say plenty of food is available
sometimes animals and plants seeking that resource can harm one another then also it
is also known as a competition.
So intraspecific and interspecific competitions are possible, that is intraspecific is the
competition within the species and members of the same species, and intraspecific competition
is between different species, let’s say for the same food resource two species are
competing.
Let’s say grazing land where different species of animals are coming and then they compete
for the same food source, how do they survive?
Competitions can be thought of as a zero sum game with clear winners and losers, that is
the contest to competition, so in the sense there will be clear losers or winners at the
end of this competition because one of them have definite advantages over the other in
gathering the resource or eating the food, so basically they will overcrowd the other
species.
Then another refreshness need to be looked into this scramble competition that is when
resources are wasted in a scramble, crowded population grow slowly because of this, because
of the scrambling the waste the resources.
So the same logistic model can be modified when there is a competition between two species
for the same resource, for to competing species one and two the population growth curve of
species one living alone can be written as DN1/DT which has the intrinsic growth rate
of R1, and the N1 is the population of that particular species at given point of time,
and K1 is the carrying capacity of the species 1, if species 1 was only occupying that space.
Similarly you can also write another expression for let’s say species 2, if it was living
alone in that habitat we can say that you know the growth rate of species 2 will be
written as DN2/DT which is equal to the intrinsic growth rate of R2 multiplied by number of
individuals of species to at that given time, and K2 is defined by the carrying capacity
if only that’s species 2 was living in that area.
Now let’s say this 2 species are coming together, so initially there will not be any
competition because there is enough food supply and resources available, but when N1 approaches
K1 or N2 approaches K2 the effects of competition becomes significant, so the equation will
become a coupled equation here, the growth curve for of species 1 in the presence of
species 2 we can write as let’s say we want to write for species, how the species 1 growing?
It can be expressed using the equation DN1/DT which is the growth rate of species 1 in the
presence of species 2, so that equation will get modified as R1N1 which into 1-N1/K1, N1
and K1 are relevant to species 1 – alpha 1 2 into N2/K1, so N2 is again relevant to
species 2, and alpha 1 2 is a coefficient which is known as the coefficient of competition.
So we will see what is this coefficient of competition?
The coefficient of competition is alpha which represents the effect that one species has
on the other, so alpha 1 2 means the effect of species 2 on species 1, so how it is positively
or negatively impacting the species, the other species.
And alpha 2 1 means the digits below alpha a subscripts indicates which species is effecting
the other one, so alpha 2 1 represents the effect of species 1 on species 2, alpha 1
2 means the effect of species 2 on 1, alpha 2 1 means the effect of species 1 on species
2.
The first number of the subscript always refers to the species being affected.
So when alpha 1 2 let’s say is lesser than this coefficient can be having a value which
is less than 1, the effect of species 2 on species 1 is less than the effect of species
1 on its on members, so that’s the meaning of alpha 1 2 being less than 1 or other words
if alpha 1 2 let’s say is greater than 1, the effect of species 2 on species 1 is greater
than the effect of species 1 on its own members, so the product of the competition coefficient
alpha 1 2 and the population size of species 2 that is N2, therefore represents the effect
of an equivalent number of individuals of species 1 and this included in the intraspecific
competition or density dependent term.
So when it comes to competition, so when there is no competition among the species, the logistic
model of growth is happening and the competition happens only within the species and the population
toppers as you could see in the logistic model, and when two species are competing for the
same resource we introduce what is known as a competition coefficient, alpha to capture
the effect of one species on the other, how it will improve, increase or decrease the
population of both the species.
So in the next session we will be looking at how if there is, in the absence of any
prey predator relationship we could use this logistic model, now let’s say we have a
predator coming into the picture, so there are herbivores and then if there are predators
how this logistic model gets modified or are there different ways in which you can capture
the population of both the prey and the predator existing in a particular place, so this will
become very complex if you have multiple species of let’s say preys and multiple species
of predators coexisting in a same ecosystem, and the population will be having different
dynamics because of this different parameters of competition called vision that is, that
will be affecting each species due to the presence of the other species in the same
area, same ecosystem.
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