Comprehensive Guide to Biodiversity and Conservation Explained

hello everyone welcome to PW English YouTube channel I'm sh sasher your bney teacher I welcome you to this lecture in

the umid ne English patch in today's class we're going to be discussing the last chapter in your syllabus which is

biodiversity and conservation in one shot so before we get started let's quickly go through the number of

questions that have been asked from this chapter over the last few years in neat uh so you can see how the range varies

between 1 and five uh it's between one and five there have been many years where just one question has been asked

and a couple of years two questions have been asked there are years where three questions and four questions have been

asked in the last year there were five questions that were that were asked from this chapter so looking at the uh number

of questions that have appeared over the last few years you can expect like around two to three questions in my

opinion from this chapter all right uh and about whether you should refer the old ncrt textbook or the new one for

this chapter neither of them will work after rationalization nothing has changed here so whichever one you have

you can study with that so let's get started what is the name of the chapter biodiversity and conservation let's

first understand what biodiversity means bio means life living organisms diversity is a general English word

which means variety right we say um in India there is unity in diversity or aware of that diversity means variety

what that basically means is though there are so many different varieties of cultures people languages across India

we all remain United in that context so with respect to biology what would biodiversity

mean diversity is variety bio is life the variety that you see in living organisms is what is biodiversity

variety refers to how many different types of species are there how many different types of ecosystems are there

how many different types of genetic variations are there all of this contributes to biodiversity for example

apparently on our planet Planet there are more than 20,000 species of ants alone just ants there are 20,000

different types different species talking about beetles which are another type of insects you have around three

lakh species of beetles present and then there are about 28,000 species of fishes and roughly around 20,000 species of

orchids which is a type of flowering plant so with just four groups of organisms we have so much variety so

imagine about all of the insects all of the uh different types of flowering plants

and just just blows your mind to think about how much diversity exists on our planet in this chapter we're going to

learn explore about numbers there's a lot of data and uh how is the biodiversity distributed is it uniformed

throughout the world is there any gradient is there um I mean any specific pattern it follows we learn about that

and and uh we will learn about how species are going extinct what can you do about it how will it affect you if

some species somewhere gets extinct and uh why should we conserve it how do we conserve it all of that okay so let's

get started the enormous variety of life that is present on Earth is what we call

biodiversity I've already told you that now there is this person an ecologist called Edward O Wilson he is referred to

as the far father of biodiversity he is the person to have popularized the term biodiversity by

using it a lot okay now according to him you know how in the previous class and even in the first chapter of of ecology

I've told you about different levels of uh biological organization we start with macro molecules then cells and tissues

and organs organism population community ecosystem biome bi spere these are the different levels in every level

diversity exists variety exists talk about biomolecules there are different types right you have proteins

carbohydrates lipids nucleic acids there is variety there talk about um cells in cells there is variety talk about

tissues there's Variety in tissues there's parena konima scen Kima different types organs there is

difference right there is variety you have root stem leaves organism there is difference population there is

difference community that is difference in not difference more like variety uh in if you look at the diversity that is

present in every level of biological organization all of that can be considered as biodiversity okay so what

he says is um he used the term biodiversity to describe the combined diversity that exists at all the levels

of biological organization of them some of them are more important and some of them are more extensively studied we're

going to study three such levels of diversity in living organisms the first one is called genetic

diversity genetic diversity is the diversity that exists within the same species think of as humans for example

we all belong to the same species right but still there is difference and variety Among Us with respect to a lot

of characters it could be the skin color it could be how tall we could grow it could be the color of your eyes it could

be the texture of your hair uh in with respect to a lot of characters we are different from each other and variety

exists now what do you think is the reason for this variety why am I brown why is my hair black why are my eyes

dark brown why is my hair wavy why am I the way I am that is because of the kind of genes that are present in me I have

more genes that produce melanin so I'm Browner in color one of you all could have fewer genes and could be paler than

me one of you all could be uh have more genes than me and be slightly more darker so why we are the way we are why

diversity exists Among Us is because of the kind of genes that we have that is why we call it genetic diversity okay

this is at the species level a single species might show high diversity at the genetic level

over its distributional range in your textbooks there are three examples given firstly there's this plant called rulia

vitoria which you can find near the himalia in this plant a chemical is produced

that is called reserpine this reserpine has medicinal properties so it's used as a drug okay similar to how the content

of melanin will vary from one person to another from one human to another the amount and concentration of resine that

one Rafia plant produces will vary with the concentration another plant produces and why is that that is because of the

kind of genes these plants have not just the concentration even the potency of the drug could vary from one one plant

to another plant even though they both belong to the same species same thing for Rice apparently there's greater than

50,000 strains of rice and around 1,000 varieties of mangoes you know about the different varieties of mangoes right I'm

sure you could you can name at least five of them because it's the national fruit and uh it it it's grown very well

in India and we are all aware of at least five varieties of mangoes there's Alfonso there's badami there's rasp Puri

there's toap Puri and there are so many different types so so all of these are different varieties belonging to the

same species they're different from each other because of the kind of genes that they have that's why we call it genetic

diversity now the second type of diversity that we're going to learn is called species diversity so this is

diversity at the species level previously what we saw was within the species level over here it is at the

species level the example that we have here is the number of amphibian species is more in the West Wern GS compared to

Eastern GS here you have the map like half map of India over here to the left to my left you have Western guts and to

the right you have Eastern guts what do we mean when I say the amphibian species is

greater in Western guts compared to Eastern guts now let's take for example in the western guts we have

yeah in the western guts we have five different types of species of amphibians there's let's call them A B C D E let's

say a there's 150 of them B there's 20 of them three there's 15 C there is 300 e there is um let's say 72 okay random

numbers I've written what I mean to say is in the western GS how many different types of species do we have we have five

different types of species just roughly hypothetically one random number I'm giving you to make you

understand it's not like Western guts has only five species okay and in eastern

guts you have just three species let's say you have let's call them p q and R there's 3,000 of P there's 2500 of Q and

there's 12,000 of r now if you look at these numbers you know that clearly the number of amphibians here is more than

the number of amphibians here but when we talking about the species diversity we're specifically focusing on how many

different species are there over here you have five different species but the total number of amphibians is less over

here you have three different species but the total number of amphibians is much higher when we talking about

species diversity we don't care how many amphibians are present the population size of amphibians we not bothered all

we care about is how many different types are there how much variety is there it's all right if there are 10

different species and probably 10 of them each in each species whenever the number of species

is more we say the species diversity in that particular area is higher okay keeping that in mind in Western GS we

find more variety of amphibians compared to the Eastern guts the number May or may not be more I'm giving you this

example not to say that in eastern guts there is more number of frogs what I'm trying to tell you here is to

differentiate that we are not looking at the individual count we not looking at the population size of each species we

looking at the number of species only that is our Prime Focus all right so here since you have more species we say

that amphibian species diversity is higher in the western guts compared to the Eastern guts now let's move on and

talk about ecological diversity ecological diversity is at the ecosystem level what is an ecosystem we've learned

it in the previous chapter an entire chapter was dedicated to ecosystem we know that ecosystem is a geographical

area uh and we include biotic abiotic components and we study the interactions that are taking place between them and

there are many different types of ecosystems now ecological diversity depends on how many different types of

ecosystems are present now let's compare to countries one tropical country like India and one Scandinavian country like

Norway which is towards the temperate regions much much far away from the equator so when you compare these two

types of ecosystems I'm sorry these two countries the number of types of ecosystems that you find in India are

much higher so in India you find uh you find desert you find um oceans um like the coastal region and

then you have um tropical forest you have Alpine Forest you have freshwater ecosystems estuaries so many different

types of ecosystems but in a u Scandinavian country like Norway you don't have that many types of ecosystems

you probably will not find oceans there uh I'm sorry you probably will not find deserts there and uh it's

mostly uh temperate forest and Alpine Forest that you can find there so the number number of different types of

ecosystem is more in India compared to Norway so we can say that India is ecologically more diverse than Norway

all right now how much biodiversity can we see in our world like can we put like a

number and tell like these many species exist on our planet there are organizations like iucn

which is international Union for conservation of Nature and and natural resources they maintain the data of how

many of species have been identified named and described so far according to their 2004 data like 20 years ago ncrt

has not updated like data according to data from 20 years ago right now the number of species that have been

discovered and described is crossed to 2 million but according to the 2004 data which ncrt has decided to stick with

there are roughly around uh 1.4 million species which includes plants and animals that have been

described so far how many more are there of course every species that is there on this planet we've not identified

described and discovered right how many more could be there there are so many different ecologists giving so many

different types of um estimates some of them say uh it could be like 30 million some of them say it could be 50 million

and a lot of estimates have been put out for how many species exist on this planet okay but there is a scientific

way of doing it how do they do it see if this is our planet let's say this is our planet

Earth at the center of the earth we have the equator right on either sides of the

Equator we have the tropical regions and then we have the temperate regions

and then we have the polar regions right so here you have equator you

have okay wait let's shade this this is your Tropics what whatever is in

pink this is the temperate regions and then here towards the poles of

course we have the polar regions now there is something called a species

inventory that is maintained okay in the species inventory there will be a list of all the species that have been

discovered and described okay now in the temperate regions the species inventory is more or less completed

almost complete for most taxonomic

groups whereas in the tropics the species inventory is kind of incomplete not as

complete complete as the temperate now what do I mean by that in temperate regions whatever different types of

species are there most of them have been discovered and described and maintained in the Tropic regions that has not been

done for most taxonomic groups now when I say taxonomic groups I mean insects birds vascular plants those kind of

groups all right excuse me I'm feeling like I might sneeze but I may not sneeze also

okay it's gone yeah uh so what we do is we take just one taxonomic group okay let's say we

consider insects you consider insects one group of

insects one type of insect you consider extensively discover and describe those species and complete the species

inventory almost as much as possible for that just one taxonomic group both in the temperate

and Tropics you know in the tropics the species diversity will always be higher than the temperate regions why I'll tell

you later just know that in the tropics there'll be more number of species compared to the temperate okay for this

one group of uh insects let's complete the um species inventory for both tropics and

temperates from that data you will get to know that if in the Tropics if in the temperate region there is X number of

species in the tropics there could be 5x if you find 1,000 different species of insects of this particular group in

the temperate regions you probably find 5,000 such species in the tropics all right so from this you get a

ratio of how much more diversity is there in the tropics compared to the temperate region now apply the same

ratio to the other groups I told you that more or less for all taxonomic groups the species inventory

is complete in the temperate regions so what do we do then we want to find out how many species of amphibians are

probably present in the tropics for the temperate amphibian is complete right let's say in the temp temperate regions

amphibians probably there is 300 species so approximately you can uh estimate that

in the tropics probably five times that 1500 species could exist using this

ratio you can find out how many species are present in the tropics like rough estimate even though the species

inventory is not fully complete so that is how you scientifically estimate how many species are yet to be discovered

and how many species are present on this Earth One such scientific estimate was made by a person called Robert May and

according to him and according to him the species diversity overall in the world global

species diversity is about 1 point I'm sorry 7 million not 1.7 7 million all right

now let's talk about global species diversity in the world there are many different species of them of the ones

that have been identified and described so far 70% of them more than 70% in fact are animals and nearly 22% of them are

plants so there is more species of animals compared to plants over here I'm not again talking about how many animals

are there how many plants are there I'm talking about a variety I'm talking about species diversity how many

different species of animals are there how many different species of plants are there if you're considering the types of

species then the species diversity of animals is higher around of all the species that

have been described so far plant animal funi around 70% or a little more than 70% is animal species and nearly 22% is

plants and that includes fungi also okay it includes bopy steropes algae um what do you call it angos sperms gymnosperms

fungi and all of those groups okay now among animals globally how is the um species diversity the most species Rich

taxonomic group is insects among all animal species 70% of animals are insects only so if you count if you

check how many uh species are present in 10 seven of them will be insect species only okay and uh the remaining less than

30% that is all of the remaining animal species now if you consider specifically invertebrates among invertebrates of

course insects are the most species Rich taxonomic group after insects you have Crustaceans I'm sorry after insects you

have molases and after molas you will have Crustaceans and then you have the other uh invertebrate taxonomic groups

you know you've learned invertebrates in Animal Kingdom right you know from porifera to echodata everything all of

those things are invertebrates all of those omic groups are invertebrates when you're considering them among them

within arthropoda insecta or insects are the most taxonomic Rich uh I mean most species Rich taxonomic group and then

you have mulas and then Crustaceans which is again belonging to arthropoda and then you have all of the other

remaining groups okay now talking about vertebrates specifically in vertebrates fishes are the most species Rich

taxonomic group after after fishes you have Birds then reptiles then amphibians and then mammals okay mammals are the

least species Rich taxonomic group fishes are the um highest species Rich taxonomic group so remember FB r a m FB

Ram fishes first then Birds then reptiles then amphibians then mammals okay that is the order now that's about

the global species diversity let's understand what is um uh that was for animal now let's understand what is the

global species diversity for plants in Plants over here in this chapter we we are including fungi also

but in biological classification we've studied how it belongs to an entirely different Kingdom over here uh fishes

are I'm sorry fungi is also considered within plant group only so you know currently anges sperms are the most

dominant and the most advanced type of plants and that is the most species Rich taxonomic group as well fungi and angers

pumps Prett pretty much have the same kind of same level of species diversity and then you have the other groups algae

lyans mosses Ferns and its allies all of those okay now I've been telling you about species diversity uh and I

mentioned plants animals and fungi but I did not give you any numbers for procaryotes we do not have I mean we

haven't included uh Pro I'm sorry procaryotes or bacteria in all of these uh calculations and

estimations uh for two important reasons there are no estimates that we have provided for procaryotes firstly

whatever conventional taxonomic methods we use for um you know describing and identifying other groups like animals

and plants and fungi it cannot be used it will not be suitable for procars like for example if um there is an uh a

bacterium which is an obligate parasite it will be difficult to culture it there are some organisms that could cause

deadly diseases and you can't uh you know it's not safe to culture them also uh sometimes what happens is they grow

in extremes of habitats extremes of climatic conditions which we cannot replicate in a lab so because of these

reasons we have not estimated the number of procaryotes and also yeah like I mentioned it's not possible to culture

all species of procaryotes inside the lab but if you start you know including the procaryotes the number of

procaryotes itself will run into several milon Millions because there are so many different species of bacteria right now

we'll talk about the contribution of India in biodiversity you know India is a tropical country it has a very very

very rich biodiversity the land that India occupies in the world is just 2.4

percentage if you consider the land mass on Earth India occupies just 2.4% of land area in

the world but it's contribution to biodiversity is a staggering 88.1% though it is occupying just a very

small piece of land it contributes to a crazy high level of biodiversity 8.1% of the world's biodiversity is contributed

because of India because of its high level of species richness India is declared as one of the 12th Mega

biodiversity countries of the world there are 12 countries that are you know um declared as the uh Mega biodiversity

countries of those 12 India is also one talking about how many plant species you can find in India nearly 45,000 species

of plants you can find in India twice as much animals roughly around 90,000 species of animals can be found in India

and if you apply Robert May's estimate over here Robert May said I mean according to iucn 2004 data 1.5 million

species have been described and he said roughly 7 million species exist on this planet apply the same estimate here

45,000 species of plants have been described so far probably one lakh species or more than that is waiting to

be described roughly around 90,000 species of animals have been described so far probably there is 3 lakh around

species of of animals present just in our country that is how crazy high the level of biodiversity is on our country

or in our country okay now let's understand patterns of biodivers so I've been telling you that

U India is ecologically more diverse than Norway I gave you this example right what does that indicate it

indicates that ecological diversity is more in India compared to Norway and ecological diversity is not uniform

throughout the world right and also what is true is species diversity is not uniform throughout the

world is there any specific pattern that you can find here yes there is we call it the latitudinal gradient what

basically happens is as you move away from the equator towards the poles it could be the North Pole or the South

Pole the species diversity is going to go on decrease progressively all right so at the equator is where you will have

the max maximum species diversity and as you move towards the poles it will

decrease it is highest at the equator and you can see a progressive decrease as you move away from the equator

towards the uh polar regions okay now let's take an example for that uh let's consider Colombia Colombia

is a country that is very very close to the equator it is present in the tropics I told you what Tropics are

right Tropics are the regions that are present adjacent to the equator around the equator uh very close to the equator

so Colombia being a country near the equator is in the tropics it has we we comparing the number of bird species

here it has 1,400 species of birds now let's consider our own country which is India it is in the um northern

hemisphere like towards the southern part of the northern hemisphere quite close to the equator and it's also part

of the tropics right so India also is a tropical country and in India we have 1200 species of birds now move slightly

ahead from the equator from India towards New York which is a state in the United States of America it belongs to

the temperate region and over there you can see how there is a drastic decrease in the number of bird species there's

just 105 of them move even farther away from the equator go to Greenland which is in the Arctic region towards the

poles and there you have only 56 species of birds so this shows how progressively there is a decrease in species diversity

As you move from the equator towards the poles right now I'll give you another example if you

consider vascular plants the species diversity in vascular plants which are the vascular plants it includes your

Tropi gymnosperms and angos sperms if you consider two regions of of similar size one in eador which is a tropical

country like the equator passes through it one is Ecuador and the other one is in um some part of Midwest of USA these

are two areas you're considering two regions one is in the uh like at the Equator the other one is farther away

from the equator in the temporate region if you consider how many species of vascular plants you can find there will

be at least 10 times more species of vascular plants found in Equador compared to the Midwest of USA you see

how that is also a drastic difference right uh there is um a forest called Amazon

rainforest in Brazil South America that is the place that is the forest where you find the highest amount of

biodiversity that is also present in the tropics in the Amazon rainforest there are more than 40,000 species of plants

around 427 mammals 13 00 species of birds 378 species of reptiles four 427 again species of mammals around 3,000

species of fishes and greater than 1 lakh 125,000 species of invertebrates and apparently it's believed that in the

Amazon rainforest at least 2 million in insect species are not yet discovered and are waiting to be discovered that's

how species diverse the Amazon rainforest is now let's talk about what is the reason for this um gradient to

exist with in terms of biodiversity why is it that there are more species in the tropics compared to

the temperate regions first reason is speciation is a function of time now for more number of species to

form speciation has to occur right speciation you've learned about it in Evolution chapter speciation is the

process by which a new species is arising from a pre-existing species for species diversity more more species have

to be there more species should have newly formed by a process called speciation and speciation does not

happen in a short period of time we didn't evolve to become modern humans from Homo habilis or Homo erectus over a

period over a short period of time it didn't happen overnight it didn't happen over a period of 10,000 years it took

several thousands of years to happen so speciation addition of more species into a region consumes time okay what has

happened in the temperate regions is very frequently glaciations have occurred you've watched the movie I AG I

suppose so you know that very frequently glaciations have taken place in the tropics now what happens is because of

glaciation whatever existing species are there they also could have gone extinct they would have gotten wiped out of the

planet and also because there is a disturbance because of glaciation there is not sufficient time available for

newer species to form but if you compare temperat with tropics and Tropics we haven't faced such glaciations much so

relatively we have gotten more time to uh you know evolve and more species to form as a result of that in the tropics

you can find more species diversity okay so frequent glaciations in temperate areas many species were killed and also

in the tropical region diversification occurred because of stable conditions so species continue to evolve and flourish

and you know new species formed over a long period of time what is the second reason here the second reason is the uh

how seasonal the two regions are the tropics and the temperate regions in all parts of the world you will experience

different seasons but the changes between two seasons are not too drastic in tropical countries as compared to

temperate countries in some temperate countries um towards the polls you can see how the day length varies the

temperature varies extremely like there are some countries in the world um which experience sunlight for six months

straight and complete darkness for the next 6 months so in such cases when very frequently seasons are changing

drastically the species will not get time to evolve they will not find their Niche Niche specialization will not take

place now what is Niche specialization let's assume there are two students uh one of them is practicing art every day

he's painting and drawing and getting better at Art because he's practicing every single day there's another student

who does art on one day and the next day he goes to a drawing class I'm sorry a guitar class on day three he goes for a

skating class on day four he goes for a swimming class on day five he's back to painting again and he does this after a

period of one year if you notice who is a better artist who draws better who paints better it's more likely that the

first student is better because he's got more practice on it so he's gotten special Iz in that field same thing

happens here just when the organisms are like okay there's too much sunlight right now let me adapt to it just after

a few months there is complete darkness and then while they're trying to adapt to that Darkness there's bright light

again so there is no constant environment in such places therefore specialization Niche specialization

becomes difficult since such conditions are not there in uh temp tropical regions in tropical regions of course we

have seasons but the variation is not too drastic therefore organisms that are thriving here get more time for Niche

specialization and they will diversify all right so relatively more constant and predictable they promote Niche

specialization greater species diversity in the tropics now final point is solar energy of

course maximum sunlight is received by the tropics and it progressively decreases as you move towards the pole

sunlight is very important for an ecosystem we know why from our previous class I've told you that um sunlight is

a very important factor for photosynthesis to take place photosynthesis how well it happens

determines the productivity uh so the productivity if of an ecosystem is more then it can

Harbor more number of species it can support more number of species since Tropics receive more sunlight there's

more productivity in the tropics as a result more species can be supported in the tropics compared to the temperate

regions all right now that's about the reasons for why Tropics are more species diverse compared to the temperate

regions now let's understand something called the species area relationship there is this German

naturalist called Alexander ju hanold he explored many jungles and forests in South America so what he basically

noticed was as he increased the area explode the number of species would also increase

okay let's consider for example um uh flowering plants okay let's start

with our house okay we are counting how many species of plants are there we are increasing the area gradually and seeing

how the species also will increase so in my house I have only one plant that is a Tulsi plant so the species diversity in

my house alone is one now let's consider my whole building my whole apartment complex there are many houses I know

some houses have Rose plants some houses have hibiscus some of them have doat I don't know what it's called in English

some of them have a jade plant some of them have a money plant so if you consider the whole building then the

number of species is going to increase include my entire Road the street that I live in there are Avenue trees there are

there's a gulm moer there is a um what do you call it pongamia tree there is a coconut tree uh there is a neem tree

there is a calotropis plant the number of species that I got encountered has increased now consider my whole locality

the number of species is further going to increase now consider my whole City Bangalore it's even going to increase

consider Karnataka it's going to increase consider the whole of India it's going to increase so as you

increase the area explored the species richness is going to also increase but not indefinitely only up to a limit okay

as you move on and explore more and more areas what will happen you will not get newer species the species would have

been already recorded earlier you're not getting newer and newer species added to your list okay

so then eventually up to a limit it will increase now if you plot this on a graph having area on the x-axis and species

richness on the y- axis what we get as a result is a rectangular hyperbola by convention the rectangular hyperbola is

represented by the equation s is equal to C A to the^ of Z where s stands for species richness C stands for the Y

inter ccept a is area Zed is the slope okay now if you plot the same thing on a logarithmic scale you're going to get

log s is equal to log C + z log a as you can see this is like a linear equation Y is equal to mx + C right so m z here you

know m is the slope so Z here is represented as the slope now if there is too many species uh that you are

encountering too many new species you're encountering every time you increase the area explored then you're going to get

like a steep curve right this line is going to be steep if it's not very steep that

means the x value I'm sorry Zed value is less if it's very steep that means the Z value or the slope value is more now

generally regardless of which uh region you consider regardless of which taxonomic group is you consider

generally ecologists have studied that for most areas for most taxonomic groups the value of Zed will lie between 0.1

and 0.2 okay it could be plants that you're considering in Britain it could be birds

in California it could be muscles fresh molas in New York it could be um whatever it could be amphibians in India

it could be any organism any part of the world most cases the range is going to be 0.1 to

0.2 but if you consider like huge geographical areas like cont continents if you want to find out how many fruit

eating bird species are there in continents as big as Asia Europe then in that case of course the Zed value will

be much higher more steeper it could range between 0.6 to 1.2 for example the fruit eating birds and mammals in the

tropical forests of different continents the slope is found to be around 1.15 which is much higher than the normal

range okay so that is species area relationship now let's talk

about why is species diversity important for an ecosystem why should there be more number of species what is its

advantage to an ecosystem if the species is more biodiversity is more then the stability of the ecosystem also will be

high ecosystem is more stable when there is more number of species how can you say that an ecosystem is stable you're

comparing two ecosystems how can you say one is more stable than the other what are the characteristics that will Define

which ecosystem is stable like for example a good teacher is a teacher who knows the subject well who can deliver

it properly and then who probably has like a neat board work and uh patient and listens to students these are traits

of a good teacher traits of a good student somebody who has Focus who has um uh no distractions and uh he has his

eyes set on his goal he will follow everything uh that the teacher says to the tea and then he's disciplined these

are good qualities of a student like that what are the qualities of a stable ecosystem when we say an ecosystem is

stable what we basically mean is in that ecosystem year to year productivity variation will not happen much like

previous year net primary productivity was x amount and this year it shouldn't be like too much of a deviation from

that when the productivity is not varying too much year after year you can like say it is a stable community or a

stable ecosystem secondly Whenever there is occasional disturbance either natural or man made there could be a forest fire

there could be a flood there could be a drought there could be alien species Invasion uh

yeah in these cases the ecosystem will be more stable it will not get affected it will be self- sustainable so um such

things will not bother the ecosystem it will be resistant to all of these things then we say that the ecosystem is stable

it is noticed that ecosystems productivity doesn't very much even if there are occasional disturbances or

alien species invading the ecosystem will still manage to sustain itself whenever the biodiversity is higher okay

so how do how do we know about this we know about this from David tilman's experiments David Tillman conducted

extensive experiments in outdoor plots he he like took different areas he considered different ecosystems with the

same area and then one of them would have more biodiversity the other one would have less biodiversity he just

noticed year after year is the productivity varying too much occasionally if there is any disturbance

which one is able to handle it better and eventually he concluded that the ones with more species were more stable

okay so he um performed experiments using outdoor plots he found that whenever more species were present in an

ecosystem less year toe variation in productivity was seen and uh more diversity contributed to even more

productivity in that ecosystem okay now you might think there are so many different species there 7 million of

them okay 500 of them getting extinct how is it going to affect my life if there are three lakh and Beetle species

then okay 10 of them going extinct how is it going to matter to my life these are some things that you might be

thinking about to help you understand how every species is so important to keep the balance in nature there's a

beautiful analogy given by Paul erlick Paul erli very well like geniusly Compares an aeroplane with an ecosystem

okay just like you have so many different parts in an aeroplane coming together put together with the helps of

nuts screws and bolts which he calls rivets in an ecosystem you have many different species that are helping it

function together so what is the comparison he's comparing an airplane with an ecosystem the rivets that are

keeping the airplane together with the species that are keeping the ecosystem as a functioning unit now let's let's

say every passenger that travels in the airplane pops up one rivet and takes it home with him him or her okay we will

compare that popping of rivets to uh species going extent in an ecosystem okay this is called the rivet popper

hypothesis because people are popping off rivets from the airplane so let's say initially when people are popping

off rivets from under the chair uh under the seat or probably from above or somewhere not so important the stability

of the plane may not be um you know compromised or the safety of the plane may not be compromised likewise if one

species out of 7 million two of them go extinct it may not initially affect the safe stability of the ecosystem that

much what is most important here is which species is going extinct which part of the plane from which part of the

plane rivets are being popped off if it's from under your chair probably the people sitting on that seat eventually

might be at risk but overall plane safety isn't damaged that much isn't compromised that much imagine somebody

pops off rivets going uh somebody's going to people are going to pop off rivets from the plane uh from the wings

of the plane which connects it to the body then what is going to happen if such important rivets are popped off

from the plane then the overall safety of the plane itself will be compromised likewise there are certain very

important species present in an ecosystem which we call the keystone species like for example honey bees

honey bees or bees are keystone species because they bring about pollination in so many different types of plants if

they go extinct the plants that were getting pollinated by them also could go extinct right so in that way which

species gets uh extinct also will matter eventually with time more and more rivets are getting popped off the safety

of the plane will definitely be compromised likewise even in an ecosystem the more and more species go

extend the uh stability of the ecosystem also will go down okay so over here he

Compares airplane with an ecosystem revets with species popping of revets with species going extinct flight safety

with the proper functioning and stability of the ecosystem revets on wings which are very very essential and

important play a key role he Compares that with key roll species I'm sorry keystone species that drive major

functions in the ecosystem all right I hope that has cleared any confusion that you may have had now why are we talking

about this so much that's because in the last few years we seeing a lot of extinctions happening on our planet

according to iucn's Red List I told you what iucn is in the beginning International Union for conservation of

Nature and natural resources they maintain a book called The Red Data Book or the red list okay they maintain that

data according to the 2004 data 338 vertebrates 87 plants 359 invertebrate species have

become extinct in the last 500 years alone if you have to name some very recent extinctions that have happened it

is the dodo the bird from macius Stellar seika a huge animal in Russia kuaga which looks partly like donkey partly

like zebra uh in Africa thine in Australia Caspian tiger Java tiger Bali tiger these three subspecies of tigers

have gone extinct very recently in the last 20 years alone 27 species have gone extinct this might seem like a very

small number 27 out of 7 million that's great I mean I mean we shouldn't be worried about that uh but you know what

for one species to form it takes thousands and thousands of years if 27 species are going extinct in just 20

years that is that is crazy alarming okay like I told you we didn't become modern humans overnight homoerectus did

not give rise to us overnight there were many many many species that came in between and then eventually uh

speciation happened and diversification happened right but uh if the species are going so many species are going extinct

in 20 years that is really alarming because to for form them for those species to form it would have taken

thousands of years all right now uh it's not like all the species all the taxonomic groups are equally threatened

to go extinct some species are found to be more vulnerable than the others if you consider vertebrates amphibians are

more vulnerable to Extinction if you consider plants gymnosperms are more vulnerable to Extinction see according

to this data currently uh 12% of all birds described are facing the threat to extinction 23% of mammals 32% of

amphibians 31% of gymnosperms you can see how almost onethird of the species of amphibians and gymnosperms are facing

a threat to Extinction overall worldwide 15,500 species are facing a threat to

Extinction what are the reasons for it we'll learn that and also is it the first time that something like this is

happening not really even in the past several times mass extinctions have taken place have been wiped out of our

planet dinosaurs have been wiped out of our planet has happened multiple times in the past but the problem about the

current mass extinction that we facing is it's much much faster compared to the previous mass extinctions and the

current mass extinction is mostly driven by human activities what are some of the reasons which which are causing uh

organisms to go extinct we learn about that there are four very important reasons we call that the evil quartet

quart is four right so the evil quartet gives us four reasons for loss of biodiversity or um organisms going

extinct the first most important one is habitat loss and fragmentation what is habitat I've told you what a habitat is

when we discussed organisms and populations habitat is the home for an organism it is a place which an organism

lives for plants and big big trees it is the forest for certain wild animals it is the forest for certain fishes it is

the oceans right so that is the habitat that is the area in which an organism resides habitat loss means what it is

losing its house okay if you cut down forest what will happen that area is cleared out right now so whatever uh

organisms that region Harbor it could be plants it could be animals they now left without a home they are homeless plants

cut down gone animals cannot find uh place to live there that is habitat loss they're losing their house what is

habitat fragmentation fragmentation is a big landmass breaking into smaller smaller fragments okay why would that

happen let's consider this is one area again this is happening because of human um activities you know human population

is always always increasing and to accommodate the needs of humans the greed of humans forests have to be cut

down humans want to eat beef for beef uh you have to uh give food so for raring of beefs you need grasses and other

things uh so they are these big big big forests are cut down and converted into grassland so that you can have food or F

to feed the cattle for beef and then uh for soybean cultivation large Forest areas have been cut down so what happens

if this entire area was first a um a forest one single piece of land mass let's say over here in this portion the

forest has been cut down to um you know probably for uh wood for Timber let's say this part has been cut down because

they are converting this area into a grassland let's say this area they've cut out because over here they want to

grow soybeans okay so what happened now what was once one big whole area is now

broken down into four different fragments now there are certain animals like tigers which require huge

territories to function initially in that L land uh large land Mass probably 20 Tigers could

coexist without much hassle but now what has happened those 20 tigers are forced into one of these four areas initially

because that was a huge area uh they could survive but right now within this small area there are probably five six

Tigers living amongst each other you know how tigers are right so they will want their uh territory they will not

want other tigers in their territory if a if a tiger from which originally was from this area let's say entered this

area or this area the tigers that are there in that area from the beginning they could fight with it and kill it

right So eventually because of this fighting and killing and killing each other the tiger population itself could

go down so that is what happens it mostly affects animals that have these that require huge territories and also

birds that have migratory habits and if they ask you which among the four reasons is the most important reason

that is driving Extinction right now it is habitat loss and fragmentation example uh tropical rainforest that once

covered more than 14% of the earth's land surface is now less than

6% Amazon rainforest which is called the lungs of the planet because they give out so much oxygen because of

photosynthesis they also millions of species uh we are I mean it Harbors but even this Amazon rainforest is being cut

down and cleared out for soy means cultivation or for conversion of uh Forest into grasslands for raising beet

beef cattle all of that uh pollution is another major reason because of pollution also habitats are degraded

whenever habitats are broken down into smaller fragments due to whatever reasons mammals and birds that require

huge territories and animals with migratory habits they are severely affected and as a result their

population will Decline and eventually they could go extinct this is our first reason what is our second reason overe

exploitation humans see Nature has enough to fulfill our needs but humans are known to be very greedy if greed is

more then nature will not be able to support it as a result we have to suffer biodiversity loss will 100%

happen we are dependent on nature for a lot of things for food for shelter and everything

but if your need I mean if your greed exceeds your need then it is bound to happen

Extinction is bound to happen okay now there are some examples of uh extinctions that have happened because

of overe exploitation passenger Pon used to be hunted down for its meat dodo was hunted for its meat Stella seika for its

Leather So they over hunted it for their own needs which turned into greed and as a result we've lost some very very

beautiful animals from our planet in the last 500 years alone many species have gone extinct solely because of overe

exploitation by humans currently many of the Marine fishes are also endangered they facing a threat to extinction

because they are over harvested all right that is overe exploitation what is the third point it is alien species

Invasion what are aliens Jadu what is alien alen alien generally is thought to be something that doesn't belong to our

planet right extraterrestrial organisms like Jadu in um Kaya Kish Jadu that is uh uh Alien we say that is alien because

it's extr terrest it does not belong to Earth it's come from some other planet so here with respect to biodiversity

what is an alien species an alien species is a species that didn't originally belong to that place either

Del deliberately or by chance it has been introduced to new area we've learned about this in organisms and

populations I told you the Havoc that um uh cactus prare cactus created in Australia when it was introduced there

from America why what really happened whenever an alien species is introduced into a new geographical area whenever a

species is introduced into a new geographical area it is called the alien species so it will not have any natural

Predators there as a result it can grow very well it will grow so so well that it will not allow species that were

present in that area for several thousands of years to survive okay it's more like you know Invasion when we talk

about invasion you know how Invaders invaded India they did not originally belong to India they came from different

parts of the world and they came to India and uh they were aliens like they didn't belong to this

region uh they came and then they invaded and when they invaded people over here Native Indians that were

living here for many many years their lives were threatened right they were not allowed to grow right that is what

will happen so um whenever these alien species or exotic species also they called they are introduced to a new area

they can pose a threat to the native species or the indigenous species that have been extend existing there from

several thousands of years that is called alien species Invasion not all alien species do that some of these

alien species could turn invasive one very good example for that is there is this lake called Lake Victoria in East

Africa in this Lake ictoria Victoria a fish a type of fish called Nile perch was introduced after the

introduction of this Nile perch which is an exotic species close to about 200 species of cichlid fishes went

extinct 200 species 200 different species of cichet fishes went extinct this was because of

alien species invasion next there are many plants that are invasive that we know about panium carrot grass

lanara and even our water hent which is scientifically called ioria we call it the Terror of Bengal that is also a very

very invasive species that will not allow native species to thrive recently in uh

India the African catfish clarus garia pinus has been introduced for AC aquaculture purposes

now this is a this is posing a threat to our native or indigenous catfishes it's not allowing it to thrive that is your

alien species in uh Invasion last point is coextinction when two species are dependent on each other in an obligate

manner then if one of them goes extinct the other one also is bound to go extinct let's say there's one animal uh

on this animal there is a parasite that is obligately associated if not for this animal this parasite cannot survive at

all if this animal goes extinct this parasite also could go extinct let's say two organisms are dependent on each

other mutualistically mutually okay there is mutualism between two uh species let's say there is a moth and

there is this uh Yuka plant we've learned about that so I'm taking that example so if the Yuka moth goes extinct

the Yuka plant also could go extinct because there is no pollinator for it if the Yuka plant goes extinct the Yuka

moth could go extinct because it doesn't know where else to lay ex right so sometimes if an organism is dependent on

another organism in obligate manner like it cannot survive without it in that case if that organism goes extinct the

other one also has high chances of going Extinction extinct so both of them could go extinct simultaneously uh in a very

short period of time since it's happening almost together together we call it coextinction

now why should we save or conserve biodiversity there are three arguments that explain it narrowly utilitarian

broadly utilitarian and ethical argument what does the narrowly utilitarian argument say we get a lot of things from

nature right we get food we get fod we get fiber we get Timber we get medicines there's a whole lot of things that you

get from nature which are economically beneficial for you right commercial importance it has because these products

that you get from nature can make you rich can fetch you money it is important for us to conserve it right that is the

narrowly utilitarian argument humans derive countless direct economic benefits from nature like we get food

from it firewood fiber construction material Industrial Products medicinal importance in fact more than 25% of

drugs that are currently sold in the market are derived from plants which is part of

nature 25,000 species of plants are used in traditional medicine worldwide like ayurva Chinese traditional medicine they

used and you can make money out of it they are of economic importance that is why we should conserve them the second

reason is uh the second argument is broadly utilitarian argument the reason here is biodiversity

because of biodiversity we get so many services in the ecosystem which are free of cost like right now if we are

breathing air we are taking oxygen from the air we not paying for it plants are giving out oxygen for free we are not

paying plants to photosynthesize we're getting food from plants for free like we're not paying plants to perform

photosynthesis right imagine how much you would have to pay you know if you go to hospitals or uh some medical

facilities and inquire how much is the cost of an oxygen cylinder you will be flabbergasted because they cost so much

but nature is giving it to us free we get to enjoy fruits we we get to enjoy uh you know vegetables all of that is

possible because of pollination is be charging any fee for pollination without pollination of course fruits will not

form right naturally it will not or it's rare So for pollination you're not charging any fees and imagine on a day

when you're feeling very low you walk Take a Walk In the Garden or go out and look at some Greenery you your mind

immediately relaxes are the plants charging money for that no birds singing in the morning the sound is so uh you

know soothing so such such things come to you free of cost right nobody pays for such Services since nature gives you

so many such Services which are you know which you can't put a price tag on which are like Priceless because of that

because nature is giving you all of these Services it's important for us to save nature that is the broadly

utilitarian argument the Third third one is the ethical argument now what is this ethical

argument you and I can't decide you uh what species should be conserved what species is okay being extinct based on

how useful it is to us in nature all organisms are equal every organism will have some innate role it will have some

role that it plays in an ecosystem even if it's not beneficial to you and I okay so it will have some intrinsic value it

will have some contribution to the ecosystem for which we will have to conserve it since we are the brainy

folks we are the intelligent species we have to be the voice for the species who cannot talk right as much as we deserve

to stay on this Earth every species regardless of whether it is useful to you or not should be conserved it is our

moral and ethical duty to make sure that all of these species survive on our planet that is our ethical argument okay

now okay we know why we should conserve biodiversity now let's understand how it can be

conserved if you want to conserve biodiversity there are two approaches that can be taken one is called insitu

conservation the other is called exitu conservation Inu conservation means onsite

conservation which means if you want to save the tiger save the Tiger in its original habitat in the same site its

natural habitat if you conserve it it then you call it insitu conservation if you take the tiger out

of its natural habitat Forest lock it up in a zoo give it all the Care that it requires and conserve it you're taking

it out from its natural habitat and conserving it elsewhere you call it exto conservation it's called

offsite conservation there are several ways in which inso conservation can be done and

also many different ways in which exito conservation can be done now let's first explore inito conservation

you have all of these different types there's hotspots and there's protected areas what are hotspots there are many

different regions of the world that are declared as biodiversity hotspots initially 25 such hotspots were declared

eventually they added nine more and currently there are 34 biodiversity hotspots in our world so what are these

hotspots how do they determine which area can be declared as a Hotpot there are a couple of things we should keep in

mind firstly the species richness in that area has to be very very high okay the number of species in that area

should be more so the biodiversity there should be high secondly in that area rapid habitat loss should be happening

like it should be a region where there is a threat for extinction thirdly there should be high

level of endemism which means endemism is when um there are species speci that are confined to a geographical area

except for that particular area that species is not found anywhere else on our planet if it goes extinct from that

part of the world it has gone extinct from the world itself because you don't find it anywhere else okay so wherever

there is accelerated habitat loss wherever there is high species richness High degree of endemism such regions are

um declared as biodiversity hotspots okay uh India also is a part of three biodiversity hotspots there's this uh

Western guts in Sri Lanka is one biodiversity hotspot Western guts of course belongs to India the Indo Burma

region and even the northeastern part of India where the Himalayas is all of these are biodiversity hotspots which

includes a part of India as well apart from that we have other protected areas like biosphere reserves we have what is

called sacred grooves sacred grooves are large tracts of forest that are venerated by the local community by the

tribal Community they themselves have religious and emotional attachment with that part of the uh ecosystem that part

of the forest that they will not allow animals to be hunted or plants to be cut down in those areas they are called

sacred groupes we have many such sacred grooves in India uh in mealia you have Kasi and jtia hills in Rajasthan you

have aravali Hills and the Western GS which is a part of madhia Pradesh I'm sorry Maharashtra and Kar K ataka and in

madhia Pradesh you have three regions sarguja Chanda and bastar in all of these regions the local communities

itself will conserve nature and protect it because they have that religious attachment towards it okay that's about

sacred groups we also have 90 national parks and around 448 wildlife sanctuaries that's about insito

conservation now let's talk about exito conservation exito conservation is off-site conservation I told you how you

take the organism that is threatened endangered from its natural habitat and conserve it in a different habitat okay

in a different region you take it out of its natural habitat and you conserve it that is offsite exito conservation why

do we do this that's because sometimes the population size would have become so small that if you leave it in its

natural habitat you can't control the external factors you don't know which Predator would come in hun and feed on

it you don't know if it falls sick it gets some disease it cannot be treated you don't know if there is uh hunting

happening there humans are poaching you never know those are things that are not under your control but if you strongly

want to conserve that species you give it similar conditions in another region as similar to its natural habitat as

possible take care of its um you know health and give it food nutritious food right amount of food at regular