vanishing species: the planet in crisis

321RESONANCE April 2010

GENERAL ARTICLE

Vanishing Species: The Planet in Crisis

Uttam Saikia, Narayan Sharma and Abhijit Das

Keywords

Species, mass extinction, biotic

crisis, hotspot.

Rapid extinction of species is one of the most serious ecologi-

cal problems faced by humanity today. Species are disap-

pearing at a pace unprecedented in the history of the planet

putting the very future of life at risk. The irony is that the root

of the crisis is another species, Homo sapiens rather than

some physical events that is poised to threaten its own sur-

vival. This article gives a brief introduction to the crisis, its

consequences and possible mitigation strategies.

Introduction

The variety of species is the foundation of biodiversity. Disap-

pearance of species per sé is not an aberrant process in the course

of time; some species naturally disappear from Earth. They may

die out because of inability to survive in the face of competition

from others, non adaptability to changing environmental condi-

tions and so on. Biologists estimated that the natural rate of

extinction is about one per million species in a year which is also

referred as ‘background’ rate of extinction. In the deep past,

species were also wiped out in large scale due to extrinsic factors

that were far beyond normal environmental regime. But life

bounced back even after such large extinctions through

rediversification and recolonization, albeit slowly, in an average

period of 10 million years. In fact, species evolution and extinc-

tions are very much a part of the evolutionary history of the biotic

world. The living world today in essence is a reflection of the past

history – old lifeforms annihilated by catastrophic events and new

ones steadily evolving post catastrophe. What we are talking

about is the alarming rate at which species are going extinct today

precipitated by reckless alteration and degradation of environ-

mental quality and putting the very future of life at risk. The

current rate of species extinction is about 1000 times faster,

perhaps greater than the prehuman one. While the appearance of

(left) Uttam Saikia

is working at High Altitude

Zoology Field Station,

Zoological Survey of India,

Solan, Himachal Pradesh.

His research interest is small

mammalian taxonomy.

(right) Narayan Sharma

is a PhD research scholar in

National Institute of

Advanced Studies, IISc

Campus, Bangalore. His area

of research is primate

ecology and behaviour.

(centre) Abhijit Das

is a PhD research scholar in

Utkal University, Orissa. His

research interest includes

taxonomy and biogeography

of herpeto-fauna of north-

eastern India.

322 RESONANCE April 2010

GENERAL ARTICLE

new species is limited by evolutionary constraints, it is not so in

the case of extinction which can be hastened massively by anthro-

pogenic interventions. To make matters worse, because of dete-

riorating environmental quality, concurrent evolution of new

species is also waning. To quote Michael Soule, “Death is one

thing, an end to birth is something else”. The scientific commu-

nity is unanimous that the world is heading towards the sixth mass

extinction event (aptly called biotic crisis), the evolutionary

repercussion of which is little understood.

The Past Mass Extinctions

If we look back at the evolutionary history of the Earth, there were

five major extinction episodes besides some smaller ones wiping

out almost the entire spectrum of biota. The species existing

today are remnants of those extinctions; in a way they are

survivours and their descendents. Scientists have estimated that

the species existing today represent only 0.1% of all those species

that ever existed on Earth [1]. The five big mass extinctions were

characterized by large-scale disappearance of species across

different environments and taxa. The first major extinction event

occurred 440 millions years before the present at the end of the

Ordovician period. It affected mainly marine life since there was

little terrestrial life at that time and supposedly wiped out 25% of

families. The second extinction event occurred 370 million years

ago at the end of the Devonian period and 19% families, mostly

marine invertebrates are presumed to be lost. The third event that

occurred 245 million years ago was the most catastrophic wiping

out an estimated 70–95 % of all species on the Earth. The fourth

extinction happened during the end of the Triassic period around

210 million years ago eliminating an estimated 23% of the

families. The fifth species crash took place 65 millions years ago

at the end of the Cretaceous period (called K/T boundary) de-

stroying about 17% of the families. The most famous casualty of

this event was dinosaurs along with numerous marine taxa.

Scientists have suggested various explanations for past extinction

events like shift in the positions of continental land masses,

sudden climatic change, rise in the sea level, volcanic eruptions

Species evolution

and extinction are

very much a part of

the evolutionary

history of the biotic

world.

The five big mass

extinctions were

characterized by

large-scale

disappearance of

species across

different

environments and

taxa.


GENERAL ARTICLE

and collision between the Earth and extraterrestrial bodies like

meteors, etc., although conclusive evidences are still lacking.

Whatever may be the causative agents, those events undoubtedly

reshaped the evolutionary history of the biotic world.

The past extinction events followed a certain trend – they were

non random. The extinctions far back in time were highly selective

affecting certain groups of organisms more severely than others.

For example, in the first extinction, Crinozoans and Cephalopods

were selectively destroyed over Poriferans and Gastropods. Like-

wise, the third mass extinction and by far the most brutal of all past

extinctions almost wiped out certain groups like Crinozoans,

Anthozoans, Bryozoans and Brachipodswhereas some other groups

like Porifera, Bivavle and Gastropods, survived. But how do we

explain this selectiveness? Based on the analysis of the past mass

extinction events, scientists have found that selectiveness of mass

extinction is partly independent of the factors that play a role in

background extinction. Specializations in various forms have

been associated with high rate of species demise, for example a

restricted diet breadth (Hypercarnivory) is associated with shorter

species duration in carnivorous mammal [2]. Non-adaptability to

changing environment is also cited as a reason for species extinc-

tion. However, these factors could be of little significance in

survivability, if causes like large-scale destruction of habitat

brought about by physical events are to operate. Nonetheless,

scientists presume that traits like occupation of unperturbed habi-

tat, wide physiological tolerances, etc., might have played a role

during those calamities.

The Sixth Extinction

The greatest diversity of lifeforms was achieved during the present

geological period i.e., the Quaternary. Higher groups of organisms

like vertebrates, flowering plants, etc., became most diverged only

30,000 years ago, very recently in geological terms. Ironically,

this also marks the beginning of a declining phase of biodiversity

as human population increased, putting pressure on other species.

Conservative estimates suggest that the Earth is probably holding

The extinctions

far back in time

were highly

selective affecting

certain groups of

organisms more

severely than

others.


GENERAL ARTICLE

some 10 million species of which approximately 1.75 million

have been described by scientists. The key question remains:

How many of them are disappearing and at what rate. Since we

are not certain how many species actually exist, it is a tricky

question to answer. Using a proxy measure of species–area

relationship, Harvard biologist Edward Wilson estimated that the

Earth is probably losing as many as 30,000 species per year; some

other estimates put the figure as high as 1,00,000 species a year!

It is predicted that within the next 50 years or so, the Earth will

lose one forth to one third of all the existing species.

Although the current extinction episode is part of a larger histori-

cal pattern, there are certain characteristics that distinguishes it

from past ones. First, unlike the previous extinctions, it has a

biotic and more precisely an anthropogenic origin rather a physi-

cal one. The growing mass of recent scientific data has amply

elucidated the nature of the current extinction; it is intimately

correlated with the spread of Homo sapiens around the world.

Secondly, its rapidity is no match to those in the deep time. While

all those past extinctions were spread over millions of years, the

recent extinction spasm is happening within a short span of time,

its origin can be traced to the arrival of human beings on the

scene. In fact, ever since humans appeared on Earth some

1,00,000 years ago, it had been acting as a catalyst of environmen-

tal change through rapid colonization and habitat modification.

The result is a biological catastrophe, as Ross Mac Phee of the

American Museum of Natural History puts it: “When humans

arrive on the landscape, the animals go”. To cite a few examples

from the recent past, the first human settlers arrived in the Pacific

island of Hawai some 1400 years ago. During the next 800 years,

two thirds of vertebrate fauna of the island vanished including

90% of bird species. In the 2000 years-long history of human

settlement in the Indian Ocean island of Madagascar, over two

dozens of vertebrate species were wiped out including many

endemics. The endemic lemurs in that island are living on a razor

edge; no one knows whether they will be able to make it into the

next decade.

Unlike the previous

extinctions, the

current extinction

has a biotic and

more precisely an

anthropogenic

origin rather a

physical one.

It is predicted that

within the next 50

years or so, the

Earth will lose one

forth to one third of

all the existing

species.


GENERAL ARTICLE

Various estimates suggest that since 1600 AD, about 85 species

of mammals and 113 species of birds have disappeared from

Earth. Understandably, this is an underestimate as it involves

only the well-studied animal groups and many species could have

gone extinct without being scientifically recorded. More alarm-

ingly, the extinction rate continued to rise with time culminating

in the present crisis and today some species are declining at a rate

far greater than anything witnessed in the past (Box 1).

Box 1. Enigmatic Decline of Species

The ongoing extinction is happening across the whole spectrum of life.

However, certain groups have been observed to decline at a rate that far

outpaces many other groups. A very conspicuous happening has been the

rapid decline of amphibian population throughout the world. Until re-

cently, this decline was considered primarily a consequence of the habitat

loss suffered by all major biomes. But scientists noticed that this decline is

also taking place in apparently pristine habitats and by the late 90s, the

scientific community realized the gravity of the situation. In a recent

assessment of the status of New World amphibians, it was found that nearly

two out of five species of new world amphibians* are threatened with

extinction. Nine species have become extinct in the last century. An

alarming 117 species have been placed in “possibly extinct” category

indicating that no extant population could be found although it has to be confirmed further and over 90% of them

possibly disappeared after 1980. What is the explanation for this drastic population decline of amphibians? The

main culprit seems unusual, a fungus belonging to a group called Chrytid. Recently, a fungus named

Batrachochytrium dendrobatidis, has been isolated from the skin of dead frogs and tadpoles. The epidemiology

of the pathogen is still sketchy, but it is suspected that they may produce toxin or affect the passage of moisture

and nutrients across the permeable skin causing death. Scientists believe that this pathogen working synergis-

tically with other factors like pesticide drift, climatic change is causing havoc on the global amphibian

population. Closer home, a much noticed case is the drastic decline of vulture populations throughout the Indian

subcontinent. The ecological role of these scavengers in maintaining a clean environment is needless to empha-

size. Populations of the two most common vultures of India, namely white-backed and long-billed vultures have

declined by over 90% during the last decade and imminent extinction looms for at least three species of Gyps

vultures in India. Microbiologists from Washington State University have found that the cause of this cata-

strophe is a veterinary drug Diclofenac widely used in anti-inflammatory treatments of livestock. The chemical

finds its way into the vulture after it eats the carcass of animals treated with the compound. Diclofenac is found

to be responsible for visceral gout and renal failure observed in dead and sick vultures. Although the drug was

banned in India since 2006, illegal stocks of this cheap drug continue to be a big factor in abetting the crisis.

In peril: Oriental white-

backed vulture.

Photo: Abhijit Das

* B E Young, S N Stuart, J S Chanson, N A Cox, and T M Boucher, Disappearing Jewels: The Status of New World

Amphibians, NatureServe, Arlington, Virginia, 2004.


GENERAL ARTICLE

There are many hypotheses to explain how humans in the recent

past, in spite of relatively small numbers and modest technolo-

gies, could have wiped out native species in the areas they

colonized. Some suggest over hunting by humans as the prime

reason for species extinction. Others propose infectious diseases

introduced by humans and their commensals as the leading cause

of extinction since the native fauna had no resistance to the

diseases. A more appealing proposition could be a combination of

multiple factors like over hunting, disease, predation or competi-

tion by introduced species and habitat destruction due to human

settlement, etc., working in concert towards their elimination.

The ongoing biodiversity crisis has greatly hastened during the

last 300–400 years since human population has increased tremen-

dously. Accompanying this population increase are technological

advancements catapulting humans as a force capable of tweaking

the environment on a massive scale. Wilson remarked, “It was a

misfortune for the living world that a carnivorous primate and

not some more benign form of animal made the breakthrough.”

British ecologist Norman Myers summarized the history of hu-

man interference of environment with an elegant analogy. If the

entire history of existence of the Earth is expressed in a year, life

did not evolve till May and became abundant only by October end

and humans emerged only five minutes before midnight on 31st

December. During the period after 1600 AD, the number of

species obliterated from the planet and those likely to go extinct

in the near future by human action in all likelihood will surpass

the magnitude of all previous mass extinctions put together and

this period represents three seconds, a blink in the evolutionary

timescale [3].

Factors Accelerating the Contemporary Extinction Crisis

Evidently, the unprecedented biodiversity crisis the Earth is

currently witnessing signifies the culmination of a chain of events

started by humans not too long ago. There are multiple anthropo-

genic factors that are interacting synergistically to bring havoc to

the living Earth. Loss of habitat and degradation of its quality are

During the period

after 1600 AD, the

number of species

obliterated from

the planet and

those likely to go

extinct in the near

future by human

action in all

likelihood will

surpass the

magnitude of all

previous mass

extinctions put

together.


GENERAL ARTICLE

the major factors. All kinds of habitat ranging from tropical

rainforest to coral reefs are destroyed or extensively modified for

human settlements, agricultural expansion, and exploitation of

natural resources. Estimates suggest that an overwhelming ma-

jority of old world tropical countries have lost more than 50% of

their original forest cover and in tropical Asia, more than 65% of

primary forest habitat is gone. Sometimes, a contiguous area is

reduced to many isolated fragments. Habitat fragmentation is

technically defined as the process whereby a large contiguous

area of habitat is both reduced in area and divided into two or

more fragments [4]. Habitat fragmentation is almost always

associated with severe reduction of habitat area but sometimes

human activities like construction of road, railroad, and power

line, result in habitat fragmentation without much reduction in

habitat area. In such ‘habitat islands’, extinction probability of

any given species is high as predicted by island biogeography

model (Box 2).

Overexploitation of natural resources is another severe threat to

biodiversity. Forests are overexploited for timber and numerous

non-timber forest products. Once a resource is identified, a

commercial market is developed and the local people start ex-

ploiting it up to total impoverishment and then turn to alternative

resources. Many of the charismatic plants and animals are being

driven to the brink of extinction by uncontrolled commercial

trade. Our national animal, tiger, most vividly portrays this

gloomy picture; it is literally hunted to extinction in most parts of

the range for purported medicinal value. The illegal trade of

wildlife worldwide is estimated at billions of dollars, only second

to illegal narcotics trade. And the consequences are obvious: the

planet is biologically poorer now than at any other time in the

history of Earth. Introduction of exotic species to local environ-

ment is also a major threat to the native biota. Geographic range

of species is delimited by climatic or geomorphic barriers and

organisms have evolved in concordance with local environment.

This natural distribution has been altered via human agencies by

way of introduction of species in alien environment, causing

Introduction of

exotic species to

local environment

is also a major

threat to the native

biota.

https://www.researchgate.net/publication/222996966_Fragmentation_of_a_forested_Rocky_Mountain_landscape_1950-1993?el=1_x_8&enrichId=rgreq-564883a58f14875fa05b8648fd8f4baf-XXX&enrichSource=Y292ZXJQYWdlOzIyNjcyODAyODtBUzo5NzM5NjIxMDAxMjE2OUAxNDAwMjMyNDc0Njcz


GENERAL ARTICLE

Box 2. Habitat Fragmentation and Island Biogeography

In a seminal work ‘The Theory of Island Biogeog-

raphy’*, Robert MacArthur and Edward Wilson

postulated a relationship between rate of coloniza-

tion and extinction in islands. They hypothesized

that the number of species occurring in an island

represents a dynamic equilibrium between arrival

of new species (immigration) and extinction of

existing ones. For a given area and degree of

isolation (distance from the colonization source),

as the number of established species increases,

immigration will decrease while extinction will

increase. For a given number of species, the immi-

gration rate decreases with distance from coloniz-

ing sources, a phenomenon known as ‘distance

effect’. On the other hand, extinction rate will

decrease with island area known as ‘area effect’.

Of late, this theory has been modified and ex-

tended and put to use in conservation biology to

address issues like the effect of habitat fragmenta-

tion on biological diversity. When a contiguous habitat is reduced to scattered smaller fragments, they are

literally ‘habitat islands’ in an inhospitable sea of degraded habitat. In such smaller ‘islands’, species

diversity will be low as there is little habitat diversity. Extinction rates will also be high as population size

will be small in such smaller areas. Small populations always suffer from problems like reduced genetic

variability and consequently lose evolutionary flexibility to cope with future environmental changes.

Furthermore, in small populations because of unavailability of potential mates, mating takes place between

close relatives. The resultant offspring are weak, sometimes sterile or may have little reproductive fitness,

a phenomenon termed as ‘inbreeding depression’. A good example is Hoolock Gibbon of NE India, one of

the most endangered primates of the world. A typical arboreal primate, it comes down from trees only under

extreme duress. Most of the habitat of this animal in North-eastern India is either destroyed or severely

fragmented. The open areas in fragmented habitat present insurmountable barriers for these arboreal creatures

forcing them to confine to small fragments. It is only a matter of time that the ill effects of habitat fragmentation

sets in fully wiping out the species through most of the range unless immediate actions are taken to reverse the

situation.

Habitat fragmentation is a major threat to

Hoolock gibbon, one of the most threat-

ened primates of the world.

Photo: Narayan Sharma

* R H MacArthur and E O Wilson, The Theory of Island Biogeography, Princeton University Press, Princeton, 1967.

significant alteration of the ecology of the introduced area thus

paving the way for exit of many native species (Box 3).


GENERAL ARTICLE

One more ominous threat to biodiversity has been global climatic

change brought about by emissions of greenhouse gases. In 2007,

The Intergovernmental Panel on Climatic Change (IPCC), a

United Nations scientific consortium predicted that by the end of

the 21st century, global surface temperature may rise by 1.8 to

4 oC and concluded that an increase of 1.5 to 2.5 oC would threaten

20 to 30% of plant and animal species of the world with extinc-

tion. In a recent technical paper entitled ‘Climate Change and

Water’ [5] IPCC reported: “There are projections of significant

extinctions in both plant and animals species. Over 5,000 plant

species could be impacted by climate change, mainly due to the

loss of suitable habitats. By 2050, the Fynbos Biome (Ericaceae-

dominated ecosystem of South Africa, which is an IUCN ‘hotspot’)

is projected to lose 51–61% of its extent due to decreased winter

precipitation. The succulent Karoo Biome, which includes 2,800

Box 3. The Menace of Invasive Species

Human-mediated introduction of alien species in new environment has been a major threat to native biota. These

species are generally introduced for aesthetic or economical purpose and at times they are introduced

unintentionally. But sometimes these introduced species run amok causing substantial alteration to the ecology

of the new areas so as to pose threat to native species and are referred as invasive species. The effect of introduced

species is more detrimental in islands or archipelagos as the native species have evolved in isolation, making

them vulnerable to introduced competitors or predators. The brown tree snake Boiga irregularis introduced into

many Pacific islands is causing havoc on the endemic bird species. In Guam islands, ten species of endemic birds

have been eaten to extinction by this snake. Another very well known example of species introduction going

horribly wrong is that of Nile Perch Lates nilotica introduced into the lake Victoria in the 1950s as a resource

for the fishing industry. Lake Victoria in East Africa bordering Kenya, Tanzania and Uganda is one of the

biggest freshwater ecological systems of the world and extraordinarily diverse with over 400 species of endemic

fishes mostly Cichlids. By 1980s, most of the endemic fish species disappeared and by 1990s, only one endemic

and two species of introduced fishes constitute the bulk of the fish biomass of the lake; the rest are either gone

or surviving in insignificant numbers. Investigations revealed that because of the predation by Nile perch, native

species (which sustain on algae and other lake flora) decreased in number resulting in an algal bloom. This

bloom caused depletion of oxygen level in the deeper layers of water effectively reducing the habitable area of

the lake. This resulted in further reduction of the number of native species, setting off a vicious cycle ultimately

annihilating almost the entire endemic fish fauna of the lake. A similar example can be cited about the

disappearance of yellow-legged frogs Rana muscosa from the high altitude lakes of Siera Nevada in Yosemite

National Park in the US. The culprit was trout fish introduced by anglers for recreational purposes. Fortunately,

the authorities are taking measures to get rid of these fishes and reintroduce the frogs in the lakes.


GENERAL ARTICLE

plant species at increased risk of extinction, is projected to

expand south-eastwards, and about 2% of the family Proteaceae

are projected to become extinct. These plants are closely associ-

ated with birds that have specialized on feeding on them. Some

mammal species, such as the zebra and nyala, which have been

shown to be vulnerable to drought induced changes in food

availability, are widely projected to suffer losses.” Understand-

ably, global climate change is emerging as the biggest nightmare

for conservationists and biologists alike.

Implications of the Present Crisis

Short term consequences: The magnitude of the biotic crisis

currently underway is amply clear from the above discussion. We

are far more impoverished of our priceless heritage than ever,

thanks to our own perilous actions. Species diversity and abun-

dance will remain low for the coming time as it takes millions of

years for replacement to occur. But how is this impoverishment

potentially detrimental to the future of this very planet or for that

matter our own future? For that answer, we need to evaluate the

value of species, both the direct value and indirect value in terms

of services rendered towards the maintenance of the ecosystem

processes.

From a utilitarian point of view, wild species provide all basic

needs of humans; food, fuel, medicine and clothing. Modern day

cultivars were originally derived from wild species and they

continue to provide new sources of food. The planet is believed to

contain 80,000 edible plant species and many unexploited species

hold great promise as source of food. All the domestic livestock

that provide protein to us are obtained from wild stock. Meat of

wild animals, so-called bush meat is a very important source of

protein in many parts of the world. Not only large vertebrates,

invertebrates like mollusks, insects also provide a large portion of

dietary protein and vitamins in some parts of Africa. Thus,

impoverishment of biodiversity means shrinkage of our food

source that could ultimately lead to widespread famine. In many

of the developing societies, various plant species provide the


GENERAL ARTICLE

most important source of energy in terms of fuelwood for house-

hold use. Likewise, plants and animals are the source of a wide

variety of compounds used to manufacture medicines. Estimates

suggest that twenty five percent of the prescriptions in the US

contain ingredients derived from plants and 20 most widespread

drugs in the US contain ingredients first identified in plants.

Some innocuous looking plant species in the deepest corners of

the tropical forest may provide the miracle to fight some dreaded

diseases of humankind. The rose periwinkle Catharanthus roseus

of Madagascar provides one of the most effective drugs to fight

blood cancers. Who knows how many such priceless species the

natural pharmacy is holding and how many are disappearing

before being discovered? The role of forest products like timber

and non-wood products in human economics can never be over-

emphasized. Any drastic reduction of these biological resources

could lead to the collapse of the economies of many societies and

its reverberations can well be imagined.

A very significant aspect of biological resources is its potential

for providing a novel property for future use. Wild species are the

source for genetic improvements of crops and, livestock. They

can provide the genetic variability needed to prevent catastrophic

crop failure, are the source of disease or drought resistant prop-

erty that can be integrated into agricultural crops. Apart from

these utilitarian benefits of species, one of the most fundamental

but less apparent services is towards the maintenance of a healthy

environment. Ecosystem productivity is such a service. Plants

have the only mechanism to harvest solar energy by photosynthe-

sis and consequent conversion to biomass. If vegetation of an area

is significantly destroyed, the ability of the system to harvest

solar energy will be greatly reduced and the consequent reduc-

tion in plant biomass upon which animals sustain and thus deple-

tion of animal community as well. Experiments have clearly

demonstrated the role of species diversity in productivity – more

diverse a community, more is the ecosystem productivity. The

role of plant communities in maintaining water quality, buffering

against flood and drought and moderation of local or regional

A very significant

aspect of biological

resources is its

potential for providing

novel property for

future use.


GENERAL ARTICLE

climate is too immense to emphasize. Ever increasing incidences

of drought, flash floods, landslides, etc, to a large extent are

outcomes of the unabated loss of Earth’s biological resources and

consequent disruption of ecosystem functioning. Even if a single

species is wiped out, it may sometime lead to a series of events

known as ‘trophic cascade’. This is especially apparent if the

species in question is at the top of the ecological pyramid and

elimination of this results in perturbations that percolate to lower

levels. For example, if a top carnivore is removed from the

system, it will result in increase in herbivore populations and

resulting negative consequence on primary producers. Thus, with

every single loss of species, the fabric of life on the planet is

undermined, and our very existence becomes more vulnerable.

Evolutionary Ramifications: The ensuing crisis of extinction is

going to affect the future of evolution of life on Earth signifi-

cantly. Myers and Knoll [6] postulated six possible evolutionary

scenarios of the biotic crisis :

1. Outburst of speciation: As species become extinct, a large

number of ecological niches become vacant that could pro-

vide evolutionary opportunity leading to an outburst of spe-

ciation. However, speciation is unlikely to match extinction

rate and probably will be centered on certain groups that

thrive in human-dominated ecosystems.

2. Proliferation of opportunistic species: If there is a preferen-

tial elimination of specialist species, opportunistic generalist

species may proliferate.

3. Depletion of the evolutionary powerhouse in tropics: Tropics

have been recognized as ‘engines of biodiversity’ as all major

groups of vertebrates and invertebrates have evolved there.

With the wanton destruction of tropical ecosystems, it is very

likely that these evolutionary powerhouses will no longer

remain so.

4. Decline in biodisparity: Biodisparity is biota’s evident mor-

phological and physiological variety and its impoverishment

could be another consequence.


GENERAL ARTICLE

5. An end to speciation of large vertebrates: It could spell a

doom to the evolution of large vertebrates in the absence of

large enough habitat.

6. Emergent novelties: There can be unpredictable emergent

novelties like explosive radiation of certain higher taxa.

Mitigating the Crisis: A key aim of conservation biology is to

find ways formitigation if not prevention of the current biodiversity

crisis. Obviously, finding a solution is a pivotal issue, after all

“nothing less than the integrity of the planet and the magnificence

of life itself is at risk”, as Wilson warned. Future of life depends

upon what we do now to prevent the loss of biodiversity. The first

step towards this direction is to identify threats to biota and those

vulnerable to these threats and then apply scientific principles

and most feasible recovery strategies to alleviate them. These

include but are not limited to conservation of species via in situ

and ex situ measures, conservation of habitat and ecosystems by

means of protected area networks, ecological restoration1, sus-

tainable resource management and most notably by enhancing

our knowledge of biodiversity. The last one is very important as

we know very little about this living heritage and any added

knowledge will greatly help in taking an informed decision about

it. Michael Novacek and Elsa Cleland [7] of the American

Museum of Natural History suggests a more wide-scale mitiga-

tion strategy beyond simple conservation of wilderness areas that

will encompass ecosystem management and improvement of the

damagingalteration to globalbiogeochemical cycles. Theypointed

out that today we live in a human dominated ecosystem and

human activity is as much part of the ecological equation as any

other factor. Thus, any recovery strategy should take into account

this factor as equally important.

The Hotspot Strategy: Setting priorities for biodiversity conser-

vation is a complex issue. Given the scarce conservation re-

sources, it is of utmost importance to ensure the best possible

returns from the amount of money and effort invested in terms of

slowing down the extinction rate. It is in this background that the

1 Ecological restoration is de-

fined as the process of inten-

tionally altering a site to estab-

lish a defined, indigenous, his-

toric ecosystem. Normally, eco-

system processes and commu-

nity structure is restored to origi-

nal state through succession if

destroyed by natural phenom-

ena. But those ecosystems se-

verely damaged by human ac-

tivity, natural restoration has

severe limitations and human

intervention is necessary for the

same. Ecological restoration in-

volves removal of the damaging

agent followed by improvement

of the physical environment and

thenreintroduction of native spe-

cies. The aim is to support a

stage from where natural suc-

cession can take place to

achieve a satisfactory recovery

(Richard B Primack, Essentials

of Conservation Biology,Sinauer

Associates Inc., pp.659, 1998).

.

Given the scarce

conservation

resources, it is of

utmost importance

to ensure the best

possible return

from the amount of

money and effort

invested in terms

of slowing down

the extinction rate.


GENERAL ARTICLE

concept of ‘hotspots’ evolved. In a landmark paper in the journal

Environmentalist, Norman Myers [8] first articulated the con-

cept of hotspot based on exceptional level of endemism and threat

level to biota. Myers then identified ten hotspots in the tropical

areas. In another influential paper in 2000, Myers et al [9]

provided a detailed scientific analysis of the concept of hotspot

and identified 25 such areas as global conservation priority. To be

recognized as a hotspot, an area has to fulfill two strict criteria: it

should contain at least 1500 species of vascular plants as endemics

and must have lost 70 % or more of its original vegetation cover.

These 25 hotspots occupying less than 1.4 % of land surfaces

contain 44 % of world’s plant species and 35 % of terrestrial

vertebrates indicating exceptional diversity and endemism. Myers

et al argued that the ongoing extinction crisis can be countered to

a large extent if these hotspots are effectively protected. The

concept of hotspots has been revisited recently and extended to

include another few regions totaling 34 in numbers [10]. Signifi-

cant parts of three hotspots namely Himalayas, Western Ghat and

Sri Lanka and Indo-Burma fall within the political boundary of

India. These three hotspots in total hold 13,209 endemic plant

species and have lost a vast majority of original habitat indicating

the gravity of threat. Since the publication of these analyses,

hotspots are attracting the attention of Governments and conser-

vation organizations directing resources for protection of these

areas. Myers estimated that more than 750 million dollars have

been spent in conservation of these areas in the last 15 years,

probably the largest financial spending ever in a single conserva-

tion endeavour.

Beyond Hotspots

Undisputedly, the concept of hotspot has been a milestone contri-

bution towards conservation of Earth’s biodiversity and effective

protection of hotspots could prevent large-scale extinction of

species to a large extent. But there are many species which are

highly threatened and restricted to a single locality. From the

viewpoint of threat and irreplaceability, these species deserve the

highest degree of conservation priority and unless some immedi-

Myers estimated that

more than 750 million

dollars have been

spent in conservation

of ‘hotspots’ in the

last 15 years,

probably the largest

financial spending

ever in a single

conservation

endeavour.


GENERAL ARTICLE

ate proactive measures are taken, they are bound to go extinct.

Based on the analysis of these threatened species across different

taxa, Taylor et al [11] identified sites where urgent conservation

action can help prevent their extinction. They identified 595 such

sites worldwide, mostly concentrated in tropical forests, on is-

lands and in mountainous areas. These areas contain at least one

of the endangered or critically endangered species as per IUCN

red list 2004 and are the sole areas where the species occur or

contain more than 95% of the global population of the species.

Their analysis revealed that out of these sites, 43% lack any legal

protection and only 34% are included fully under protected area

network. Although these species are highly threatened, their

recovery is a definite possibility if protection of those sites can be

ensured. Conservationists argue that these sites are a critical

subset of global conservation priority, complementing other con-

servation actions and represent clear opportunities for urgent

conservation action to prevent species loss.

Postscript: The biological diversity we see around today is the

product of millions of years of unique evolutionary transforma-

tions and is a common global heritage. Every species is as much

a part of this heritage as we humans are. Thus, leaving aside other

justifications, as the most intelligent creature on Earth, it is our

moral responsibility to protect this priceless legacy from eternal

annihilation.

Acknowledgement

This article is based on various published literature, a few of them

are indicated in the suggested reading.

Suggested Reading

[1] American Museum of Natural History, Humans and Other

Catastrophes: Perspectives on Extinction, Center for Biodiversity

and Conservation, AMNH, New York. 1999

[2] A Purvis, K E Jones and G M Mace, Extinction, BioEssays, Vol.22,

pp.1123–1133, 2000.

[3] N Myers, The Sinking Ark: A New Look at the Problem of Disappearing

Species, Pergamon Press, pp.307, 1979.

As the most

intelligent creature

on Earth, it is our

moral

responsibility to

protect this

priceless legacy

from eternal

annihilation.

https://www.researchgate.net/publication/7426547_Pinpointing_and_preventing_imminent_extinctions?el=1_x_8&enrichId=rgreq-564883a58f14875fa05b8648fd8f4baf-XXX&enrichSource=Y292ZXJQYWdlOzIyNjcyODAyODtBUzo5NzM5NjIxMDAxMjE2OUAxNDAwMjMyNDc0Njcz


GENERAL ARTICLE

[4] R A Reed, J Johnson-Barnard and W L Baker, Fragmentation of a

forested Rocky Mountain landscape 1950–1993, Biological Conser-

vation, Vol.75, pp.267–277, 1996

[5] B C Bates, Z W Kundzewicz, S Wu and J P Palutikof, (Eds.), Climate

Change and Water, Technical Paper of the Intergovernmental Panel

on Climate Change, IPCC Secretariat, Geneva, 210 pp, 2008.

[6] N Myers and A Knoll, The Biotic crisis and the future of evolution,

Proceedings of the NationalAcademy ofSciences, Vol.98No.10, pp.5389-

5392, 2001.

[7] M Novacek and E Cleland, The current biodiversity extinction event:

Scenarios for mitigation and recovery, Proceedings of the National

Academy of Sciences, Vol.98, No.10, pp.5466–5470, 2001.

[8] N Myers, Threatened biotas: ‘hotspots’ in tropical forests,

Environmentalist, Vol.8, pp.187–208, 1988.

[9] N Myers, C G Mittermeier, G A Mittermeier, G A B da Fonseca and

J Kent, Biodiversity hotspots for conservation priorities, Nature

Vol.403, pp.853–858, 2000.

[10] R A Mittermeier, P Robles-Gil, M Hoffmann, J D Pilgrim, T M

Brooks, C G Mittermeier, J L Lamoreux and G Fonseca, Hotspots

Revisited: Earth’sBiologically Richest and Most Endangered Terrestrial

Ecoregions (CEMEX, Mexico City), 2004

[11] T Ricketts, E Dinerstein, T Boucher, T M Brooks, S H M Butchart, M

Hoffmann, J F Lamoreux, J Morrison, M Parr, J D Pilgrim, A S L

Rodrigues, W Sechrestf , G E Wallace, K Berlin, J Bielby, N D Burgess,

D R Church, N Cox, D Knox, C Loucks, G W Luck, L L Master, R

Moore, R Naidoo, R Ridgely, G E Schatz, G Shire, H Strand, W

Wettengel andE Wikramanayak,Pinpointing andpreventing imminent

extinction, Proceedings of the National Academy of Sciences, Vol.102,

No.51, pp.18497–18501, 2005.

[12] W A Nierenberg (Ed), Encyclopedia of Environmental Biology, Vol.2,

pp.371–379, Academic Press, San Diego. 1995.

Address for Correspondence

Uttam Saikia

High Altitude Zoology Field

Station, Zoological Survey

of India, Saproon, Solan,

H.P.173211

Email:

[email protected]

Narayan Sharma

Email:

[email protected]

Abhijit Das

Email:

[email protected]

https://www.researchgate.net/publication/11993717_The_biotic_crisis_and_the_future_of_Evolution?el=1_x_8&enrichId=rgreq-564883a58f14875fa05b8648fd8f4baf-XXX&enrichSource=Y292ZXJQYWdlOzIyNjcyODAyODtBUzo5NzM5NjIxMDAxMjE2OUAxNDAwMjMyNDc0Njcz
















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